diff --git a/init/libprefetch/prefetch/Android.bp b/init/libprefetch/prefetch/Android.bp
new file mode 100644
index 0000000..778ea8a
--- /dev/null
+++ b/init/libprefetch/prefetch/Android.bp
@@ -0,0 +1,80 @@
+//
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package {
+    default_team: "trendy_team_android_kernel",
+    default_applicable_licenses: ["Android-Apache-2.0"],
+}
+
+rust_library_rlib {
+    name: "libprefetch_rs",
+    crate_name: "prefetch_rs",
+    srcs: ["src/lib.rs"],
+    rustlibs: [
+        "libandroid_logger",
+        "libargh",
+        "libchrono",
+        "libcrc32fast",
+        "libcsv",
+        "liblibc",
+        "liblog_rust",
+        "liblru_cache",
+        "libnix",
+        "librand",
+        "librayon",
+        "libregex",
+        "libserde_cbor",
+        "libserde_json",
+        "libserde",
+        "libthiserror",
+        "libwalkdir",
+        "librustutils",
+    ],
+    prefer_rlib: true,
+    features: [
+        "derive",
+        "error-context",
+        "help",
+        "std",
+        "usage",
+        "use_argh",
+    ],
+}
+
+rust_binary {
+    name: "prefetch",
+    crate_name: "prefetch",
+    srcs: ["src/main.rs"],
+    rustlibs: [
+        "libprefetch_rs",
+        "liblog_rust",
+        "libandroid_logger",
+    ],
+    prefer_rlib: true,
+    features: [
+        "default",
+        "derive",
+        "error-context",
+        "help",
+        "std",
+        "usage",
+        "use_argh",
+    ],
+    init_rc: [
+        "prefetch.rc",
+    ],
+}
+
+// TODO: Add rust_test to enable unit testing - b/378554334
diff --git a/init/libprefetch/prefetch/Cargo.lock b/init/libprefetch/prefetch/Cargo.lock
new file mode 100644
index 0000000..d6b214d
--- /dev/null
+++ b/init/libprefetch/prefetch/Cargo.lock
@@ -0,0 +1,743 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "aho-corasick"
+version = "0.7.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7404febffaa47dac81aa44dba71523c9d069b1bdc50a77db41195149e17f68e5"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "android_log-sys"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85965b6739a430150bdd138e2374a98af0c3ee0d030b3bb7fc3bddff58d0102e"
+
+[[package]]
+name = "android_logger"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9ed09b18365ed295d722d0b5ed59c01b79a826ff2d2a8f73d5ecca8e6fb2f66"
+dependencies = [
+ "android_log-sys",
+ "env_logger",
+ "lazy_static",
+ "log",
+]
+
+[[package]]
+name = "argh"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ab257697eb9496bf75526f0217b5ed64636a9cfafa78b8365c71bd283fcef93e"
+dependencies = [
+ "argh_derive",
+ "argh_shared",
+]
+
+[[package]]
+name = "argh_derive"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b382dbd3288e053331f03399e1db106c9fb0d8562ad62cb04859ae926f324fa6"
+dependencies = [
+ "argh_shared",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "argh_shared"
+version = "0.1.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5693f39141bda5760ecc4111ab08da40565d1771038c4a0250f03457ec707531"
+dependencies = [
+ "serde",
+]
+
+[[package]]
+name = "atty"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
+dependencies = [
+ "hermit-abi 0.1.19",
+ "libc",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
+
+[[package]]
+name = "bincode"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b92615d57e4048e480bd7e3c2d7f6ec252819fffec95efbc30ec7c68744aa66c"
+dependencies = [
+ "byteorder",
+ "serde",
+]
+
+[[package]]
+name = "bitflags"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b048fb63fd8b5923fc5aa7b340d8e156aec7ec02f0c78fa8a6ddc2613f6f71de"
+
+[[package]]
+name = "bstr"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a40b47ad93e1a5404e6c18dec46b628214fee441c70f4ab5d6942142cc268a3d"
+dependencies = [
+ "lazy_static",
+ "memchr",
+ "regex-automata",
+ "serde",
+]
+
+[[package]]
+name = "byteorder"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "cfg_aliases"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd16c4719339c4530435d38e511904438d07cce7950afa3718a84ac36c10e89e"
+
+[[package]]
+name = "chrono"
+version = "0.4.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "670ad68c9088c2a963aaa298cb369688cf3f9465ce5e2d4ca10e6e0098a1ce73"
+dependencies = [
+ "libc",
+ "num-integer",
+ "num-traits",
+ "serde",
+ "time",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "crc32fast"
+version = "1.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b540bd8bc810d3885c6ea91e2018302f68baba2129ab3e88f32389ee9370880d"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "crossbeam-channel"
+version = "0.5.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "176dc175b78f56c0f321911d9c8eb2b77a78a4860b9c19db83835fea1a46649b"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-deque"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "613f8cc01fe9cf1a3eb3d7f488fd2fa8388403e97039e2f73692932e291a770d"
+dependencies = [
+ "crossbeam-epoch",
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-epoch"
+version = "0.9.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
+dependencies = [
+ "crossbeam-utils",
+]
+
+[[package]]
+name = "crossbeam-utils"
+version = "0.8.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "248e3bacc7dc6baa3b21e405ee045c3047101a49145e7e9eca583ab4c2ca5345"
+
+[[package]]
+name = "csv"
+version = "1.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "22813a6dc45b335f9bade10bf7271dc477e81113e89eb251a0bc2a8a81c536e1"
+dependencies = [
+ "bstr",
+ "csv-core",
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "csv-core"
+version = "0.1.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5efa2b3d7902f4b634a20cae3c9c4e6209dc4779feb6863329607560143efa70"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "either"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a26ae43d7bcc3b814de94796a5e736d4029efb0ee900c12e2d54c993ad1a1e07"
+
+[[package]]
+name = "env_logger"
+version = "0.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a19187fea3ac7e84da7dacf48de0c45d63c6a76f9490dae389aead16c243fce3"
+dependencies = [
+ "atty",
+ "humantime",
+ "log",
+ "regex",
+ "termcolor",
+]
+
+[[package]]
+name = "fuchsia-cprng"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a06f77d526c1a601b7c4cdd98f54b5eaabffc14d5f2f0296febdc7f357c6d3ba"
+
+[[package]]
+name = "getrandom"
+version = "0.2.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "190092ea657667030ac6a35e305e62fc4dd69fd98ac98631e5d3a2b1575a12b5"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi 0.11.0+wasi-snapshot-preview1",
+]
+
+[[package]]
+name = "half"
+version = "1.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "eabb4a44450da02c90444cf74558da904edde8fb4e9035a9a6a4e15445af0bd7"
+
+[[package]]
+name = "hermit-abi"
+version = "0.1.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "62b467343b94ba476dcb2500d242dadbb39557df889310ac77c5d99100aaac33"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "hermit-abi"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5d3d0e0f38255e7fa3cf31335b3a56f05febd18025f4db5ef7a0cfb4f8da651f"
+
+[[package]]
+name = "humantime"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9a3a5bfb195931eeb336b2a7b4d761daec841b97f947d34394601737a7bba5e4"
+
+[[package]]
+name = "itoa"
+version = "0.4.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b71991ff56294aa922b450139ee08b3bfc70982c6b2c7562771375cf73542dd4"
+
+[[package]]
+name = "kernel32-sys"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
+dependencies = [
+ "winapi 0.2.8",
+ "winapi-build",
+]
+
+[[package]]
+name = "lazy_static"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
+
+[[package]]
+name = "libc"
+version = "0.2.162"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "18d287de67fe55fd7e1581fe933d965a5a9477b38e949cfa9f8574ef01506398"
+
+[[package]]
+name = "linked-hash-map"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0717cef1bc8b636c6e1c1bbdefc09e6322da8a9321966e8928ef80d20f7f770f"
+
+[[package]]
+name = "log"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
+dependencies = [
+ "cfg-if",
+]
+
+[[package]]
+name = "lru-cache"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "31e24f1ad8321ca0e8a1e0ac13f23cb668e6f5466c2c57319f6a5cf1cc8e3b1c"
+dependencies = [
+ "linked-hash-map",
+]
+
+[[package]]
+name = "memchr"
+version = "2.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0ee1c47aaa256ecabcaea351eae4a9b01ef39ed810004e298d2511ed284b1525"
+
+[[package]]
+name = "nix"
+version = "0.28.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ab2156c4fce2f8df6c499cc1c763e4394b7482525bf2a9701c9d79d215f519e4"
+dependencies = [
+ "bitflags",
+ "cfg-if",
+ "cfg_aliases",
+ "libc",
+]
+
+[[package]]
+name = "num-integer"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "225d3389fb3509a24c93f5c29eb6bde2586b98d9f016636dff58d7c6f7569cd9"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
+dependencies = [
+ "autocfg",
+]
+
+[[package]]
+name = "num_cpus"
+version = "1.16.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4161fcb6d602d4d2081af7c3a45852d875a03dd337a6bfdd6e06407b61342a43"
+dependencies = [
+ "hermit-abi 0.3.4",
+ "libc",
+]
+
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
+[[package]]
+name = "prefetch"
+version = "0.1.0"
+dependencies = [
+ "android_logger",
+ "argh",
+ "bincode",
+ "chrono",
+ "crc32fast",
+ "csv",
+ "env_logger",
+ "libc",
+ "log",
+ "lru-cache",
+ "memchr",
+ "nix",
+ "proc-macro2",
+ "quote",
+ "rand 0.8.5",
+ "rayon",
+ "rayon-core",
+ "regex",
+ "serde",
+ "serde_cbor",
+ "serde_derive",
+ "serde_json",
+ "tempfile",
+ "thiserror",
+ "thiserror-impl",
+ "walkdir",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.26"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a152013215dca273577e18d2bf00fa862b89b24169fb78c4c95aeb07992c9cec"
+dependencies = [
+ "unicode-xid",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3d0b9745dc2debf507c8422de05d7226cc1f0644216dfdfead988f9b1ab32a7"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "rand"
+version = "0.3.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "64ac302d8f83c0c1974bf758f6b041c6c8ada916fbb44a609158ca8b064cc76c"
+dependencies = [
+ "libc",
+ "rand 0.4.6",
+]
+
+[[package]]
+name = "rand"
+version = "0.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "552840b97013b1a26992c11eac34bdd778e464601a4c2054b5f0bff7c6761293"
+dependencies = [
+ "fuchsia-cprng",
+ "libc",
+ "rand_core 0.3.1",
+ "rdrand",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "rand"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core 0.6.4",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core 0.6.4",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a6fdeb83b075e8266dcc8762c22776f6877a63111121f5f8c7411e5be7eed4b"
+dependencies = [
+ "rand_core 0.4.2",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c33a3c44ca05fa6f1807d8e6743f3824e8509beca625669633be0acbdf509dc"
+
+[[package]]
+name = "rand_core"
+version = "0.6.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "rayon"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8b0d8e0819fadc20c74ea8373106ead0600e3a67ef1fe8da56e39b9ae7275674"
+dependencies = [
+ "autocfg",
+ "crossbeam-deque",
+ "either",
+ "rayon-core",
+]
+
+[[package]]
+name = "rayon-core"
+version = "1.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ab346ac5921dc62ffa9f89b7a773907511cdfa5490c572ae9be1be33e8afa4a"
+dependencies = [
+ "crossbeam-channel",
+ "crossbeam-deque",
+ "crossbeam-utils",
+ "lazy_static",
+ "num_cpus",
+]
+
+[[package]]
+name = "rdrand"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "678054eb77286b51581ba43620cc911abf02758c91f93f479767aed0f90458b2"
+dependencies = [
+ "rand_core 0.3.1",
+]
+
+[[package]]
+name = "redox_syscall"
+version = "0.1.57"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41cc0f7e4d5d4544e8861606a285bb08d3e70712ccc7d2b84d7c0ccfaf4b05ce"
+
+[[package]]
+name = "regex"
+version = "1.4.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a26af418b574bd56588335b3a3659a65725d4e636eb1016c2f9e3b38c7cc759"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.1.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c230d73fb8d8c1b9c0b3135c5142a8acee3a0558fb8db5cf1cb65f8d7862132"
+
+[[package]]
+name = "regex-syntax"
+version = "0.6.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f162c6dd7b008981e4d40210aca20b4bd0f9b60ca9271061b07f78537722f2e1"
+
+[[package]]
+name = "ryu"
+version = "1.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f98d2aa92eebf49b69786be48e4477826b256916e84a57ff2a4f21923b48eb4c"
+
+[[package]]
+name = "same-file"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93fc1dc3aaa9bfed95e02e6eadabb4baf7e3078b0bd1b4d7b6b0b68378900502"
+dependencies = [
+ "winapi-util",
+]
+
+[[package]]
+name = "serde"
+version = "1.0.123"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "92d5161132722baa40d802cc70b15262b98258453e85e5d1d365c757c73869ae"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_cbor"
+version = "0.11.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2bef2ebfde456fb76bbcf9f59315333decc4fda0b2b44b420243c11e0f5ec1f5"
+dependencies = [
+ "half",
+ "serde",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.123"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9391c295d64fc0abb2c556bad848f33cb8296276b1ad2677d1ae1ace4f258f31"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "serde_json"
+version = "1.0.62"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea1c6153794552ea7cf7cf63b1231a25de00ec90db326ba6264440fa08e31486"
+dependencies = [
+ "itoa",
+ "ryu",
+ "serde",
+]
+
+[[package]]
+name = "syn"
+version = "1.0.80"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d010a1623fbd906d51d650a9916aaefc05ffa0e4053ff7fe601167f3e715d194"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-xid",
+]
+
+[[package]]
+name = "tempfile"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "11ce2fe9db64b842314052e2421ac61a73ce41b898dc8e3750398b219c5fc1e0"
+dependencies = [
+ "kernel32-sys",
+ "libc",
+ "rand 0.3.23",
+ "redox_syscall",
+ "winapi 0.2.8",
+]
+
+[[package]]
+name = "termcolor"
+version = "1.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "06794f8f6c5c898b3275aebefa6b8a1cb24cd2c6c79397ab15774837a0bc5755"
+dependencies = [
+ "winapi-util",
+]
+
+[[package]]
+name = "thiserror"
+version = "1.0.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e0f4a65597094d4483ddaed134f409b2cb7c1beccf25201a9f73c719254fa98e"
+dependencies = [
+ "thiserror-impl",
+]
+
+[[package]]
+name = "thiserror-impl"
+version = "1.0.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7765189610d8241a44529806d6fd1f2e0a08734313a35d5b3a556f92b381f3c0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "time"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1b797afad3f312d1c66a56d11d0316f916356d11bd158fbc6ca6389ff6bf805a"
+dependencies = [
+ "libc",
+ "wasi 0.10.0+wasi-snapshot-preview1",
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "unicode-xid"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f962df74c8c05a667b5ee8bcf162993134c104e96440b663c8daa176dc772d8c"
+
+[[package]]
+name = "walkdir"
+version = "2.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d71d857dc86794ca4c280d616f7da00d2dbfd8cd788846559a6813e6aa4b54ee"
+dependencies = [
+ "same-file",
+ "winapi-util",
+]
+
+[[package]]
+name = "wasi"
+version = "0.10.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a143597ca7c7793eff794def352d41792a93c481eb1042423ff7ff72ba2c31f"
+
+[[package]]
+name = "wasi"
+version = "0.11.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9c8d87e72b64a3b4db28d11ce29237c246188f4f51057d65a7eab63b7987e423"
+
+[[package]]
+name = "winapi"
+version = "0.2.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "167dc9d6949a9b857f3451275e911c3f44255842c1f7a76f33c55103a909087a"
+
+[[package]]
+name = "winapi"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5c839a674fcd7a98952e593242ea400abe93992746761e38641405d28b00f419"
+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-build"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d315eee3b34aca4797b2da6b13ed88266e6d612562a0c46390af8299fc699bc"
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac3b87c63620426dd9b991e5ce0329eff545bccbbb34f3be09ff6fb6ab51b7b6"
+
+[[package]]
+name = "winapi-util"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f29e6f9198ba0d26b4c9f07dbe6f9ed633e1f3d5b8b414090084349e46a52596"
+dependencies = [
+ "winapi 0.3.9",
+]
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "712e227841d057c1ee1cd2fb22fa7e5a5461ae8e48fa2ca79ec42cfc1931183f"
diff --git a/init/libprefetch/prefetch/Cargo.toml b/init/libprefetch/prefetch/Cargo.toml
new file mode 100644
index 0000000..7da4fc6
--- /dev/null
+++ b/init/libprefetch/prefetch/Cargo.toml
@@ -0,0 +1,51 @@
+[package]
+name = "prefetch"
+version = "0.1.0"
+edition = "2018"
+default-run = "prefetch"
+
+[lib]
+name = "prefetch_rs"
+path = "src/lib.rs"
+
+[[bin]]
+name = "prefetch"
+path = "src/main.rs"
+
+[features]
+default = ["use_argh"]
+use_argh = ["argh"]
+
+[dependencies]
+argh = { version = "0.1.10", optional = true }
+chrono = { version = "=0.4.19", features = ["serde"] }
+crc32fast = "1.2.1"
+csv = "=1.1.6"
+libc = "0.2.82"
+log = "=0.4.14"
+lru-cache = "0.1.2"
+memchr = "=2.3.4"
+nix = {version = "0.28", features = ["fs", "time", "feature", "mman", "uio"]}
+proc-macro2 = "=1.0.26"
+quote = "=1.0.9"
+rand = "0.8.3"
+rayon = "=1.5.0"
+rayon-core = "=1.9.0"
+regex = "1.4.5"
+serde = { version = "*", features = ["derive"] }
+serde_cbor = "0.11.2"
+serde_derive = "=1.0.123"
+serde_json = "=1.0.62"
+thiserror = "=1.0.24"
+thiserror-impl = "1.0.24"
+walkdir = "2.3.2"
+
+# crates required for android builds
+[target.'cfg(target_os = "android")'.dependencies]
+android_logger = "0.10.1"
+
+# crates not present in android builds
+[target.'cfg(not(target_os = "android"))'.dependencies]
+bincode = "=0.9.0"
+env_logger = "=0.8.4"
+tempfile = "2.2.0"
diff --git a/init/libprefetch/prefetch/OWNERS b/init/libprefetch/prefetch/OWNERS
new file mode 100644
index 0000000..a1b54bf
--- /dev/null
+++ b/init/libprefetch/prefetch/OWNERS
@@ -0,0 +1,3 @@
+akailash@google.com
+auradkar@google.com
+takayas@google.com
diff --git a/init/libprefetch/prefetch/prefetch.rc b/init/libprefetch/prefetch/prefetch.rc
new file mode 100644
index 0000000..9f2cb7f
--- /dev/null
+++ b/init/libprefetch/prefetch/prefetch.rc
@@ -0,0 +1,13 @@
+service prefetch_record /system/bin/prefetch record --duration ${ro.prefetch_boot.duration_s:-0}
+    class main
+    user root
+    group root system
+    disabled
+    oneshot
+
+service prefetch_replay /system/bin/prefetch replay --io-depth ${ro.prefetch_boot.io_depth:-2} --max-fds ${ro.prefetch_boot.max_fds:-128}
+    class main
+    user root
+    group root system
+    disabled
+    oneshot
diff --git a/init/libprefetch/prefetch/src/args.rs b/init/libprefetch/prefetch/src/args.rs
new file mode 100644
index 0000000..4c1e689
--- /dev/null
+++ b/init/libprefetch/prefetch/src/args.rs
@@ -0,0 +1,108 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+pub(crate) static DEFAULT_IO_DEPTH: u16 = 2;
+pub(crate) static DEFAULT_MAX_FDS: u16 = 128;
+pub(crate) static DEFAULT_EXIT_ON_ERROR: bool = false;
+
+mod args_argh;
+use args_argh as args_internal;
+
+use std::path::Path;
+use std::path::PathBuf;
+use std::process::exit;
+
+pub use args_internal::OutputFormat;
+pub use args_internal::ReplayArgs;
+pub use args_internal::TracerType;
+pub use args_internal::{DumpArgs, MainArgs, RecordArgs, SubCommands};
+use serde::Deserialize;
+use serde::Serialize;
+
+use crate::Error;
+use log::error;
+
+// Deserialized form of the config file
+#[derive(Clone, Debug, Default, Deserialize, Serialize, Eq, PartialEq)]
+pub struct ConfigFile {
+    // Files to be excluded in prefetch. These files might have been
+    // added in the record file while recording,but we do not want to
+    // replay these files. These can be two types of files:
+    // 1) installation-specific files (e.g. files in /data) and
+    // 2) large files which we do not want to load in replay (e.g. APK files).
+    pub files_to_exclude_regex: Vec<String>,
+    // Files that are not in the record file, but need to be loaded during replay
+    pub additional_replay_files: Vec<String>,
+}
+
+fn verify_and_fix(args: &mut MainArgs) -> Result<(), Error> {
+    match &mut args.nested {
+        SubCommands::Record(arg) => {
+            if arg.debug && arg.int_path.is_none() {
+                arg.int_path = Some(PathBuf::from(format!("{}.int", arg.path.to_str().unwrap())));
+            }
+
+            if let Some(p) = &arg.int_path {
+                ensure_path_doesnt_exist(p)?;
+            }
+        }
+        SubCommands::Replay(arg) => {
+            ensure_path_exists(&arg.path)?;
+            if !arg.config_path.as_os_str().is_empty() {
+                ensure_path_exists(&arg.config_path)?;
+            }
+        }
+        SubCommands::Dump(arg) => {
+            ensure_path_exists(&arg.path)?;
+        }
+    }
+    Ok(())
+}
+
+/// Returns error if the given path at `p` exist.
+pub(crate) fn ensure_path_doesnt_exist(p: &Path) -> Result<(), Error> {
+    if p.exists() {
+        Err(Error::InvalidArgs {
+            arg_name: "path".to_string(),
+            arg_value: p.display().to_string(),
+            error: "Path already exists".to_string(),
+        })
+    } else {
+        Ok(())
+    }
+}
+
+/// Returns error if the given path at `p` doesn't exist.
+pub(crate) fn ensure_path_exists(p: &Path) -> Result<(), Error> {
+    if p.is_file() {
+        Ok(())
+    } else {
+        Err(Error::InvalidArgs {
+            arg_name: "path".to_string(),
+            arg_value: p.display().to_string(),
+            error: "Path does not exist".to_string(),
+        })
+    }
+}
+
+/// Builds `MainArgs` from command line arguments. On error prints error/help message
+/// and exits.
+pub fn args_from_env() -> MainArgs {
+    let mut args = args_internal::args_from_env();
+    if let Err(e) = verify_and_fix(&mut args) {
+        error!("failed to verify args: {}", e);
+        exit(1);
+    }
+    args
+}
diff --git a/init/libprefetch/prefetch/src/args/args_argh.rs b/init/libprefetch/prefetch/src/args/args_argh.rs
new file mode 100644
index 0000000..8ac95fc
--- /dev/null
+++ b/init/libprefetch/prefetch/src/args/args_argh.rs
@@ -0,0 +1,217 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::{option::Option, path::PathBuf, result::Result::Ok, str::FromStr};
+
+use argh::FromArgs;
+use serde::Deserialize;
+
+use crate::args::DEFAULT_EXIT_ON_ERROR;
+use crate::args::DEFAULT_IO_DEPTH;
+use crate::args::DEFAULT_MAX_FDS;
+use crate::Error;
+
+/// prefetch-rs
+#[derive(Eq, PartialEq, Debug, Default, FromArgs)]
+pub struct MainArgs {
+    /// subcommands
+    #[argh(subcommand)]
+    pub nested: SubCommands,
+}
+
+/// Sub commands for prefetch functions
+#[derive(Eq, PartialEq, Debug, FromArgs)]
+#[argh(subcommand)]
+pub enum SubCommands {
+    /// Records prefetch data.
+    Record(RecordArgs),
+    /// Replays from prefetch data
+    Replay(ReplayArgs),
+    /// Dump prefetch data in human readable format
+    Dump(DumpArgs),
+}
+
+impl Default for SubCommands {
+    fn default() -> Self {
+        Self::Dump(DumpArgs::default())
+    }
+}
+
+fn default_path() -> PathBuf {
+    PathBuf::from("/metadata/prefetch/prefetch.pack")
+}
+
+fn parse_tracing_instance(value: &str) -> Result<Option<String>, String> {
+    Ok(Some(value.to_string()))
+}
+
+#[derive(Eq, PartialEq, Debug, Default, FromArgs)]
+/// Records prefect data.
+#[argh(subcommand, name = "record")]
+pub struct RecordArgs {
+    /// duration in seconds to record the data
+    ///
+    /// On Android, if duration count is set to zero, recording
+    /// will continue until the property sys.boot_completed = 1.
+    #[argh(option)]
+    pub duration: u16,
+
+    /// file path where the records will be written to
+    ///
+    /// A new file is created at the given path. If the path exists, it
+    /// will be overwritten
+    #[argh(option, default = "default_path()")]
+    pub path: PathBuf,
+
+    /// when set an intermediate file will be created that provides more information
+    /// about collected data.
+    #[argh(option, default = "false")]
+    pub debug: bool,
+
+    /// file path where the intermediate file will be written to
+    ///
+    /// A new file is created at the given path. Errors out if the file
+    /// already exists.
+    #[argh(option)]
+    pub int_path: Option<PathBuf>,
+
+    /// size of the trace buffer which holds trace events. We need larger
+    /// buffer on a system that has faster disks or has large number of events
+    /// enabled. Defaults to TRACE_BUFFER_SIZE_KIB KiB.
+    #[argh(option, long = "trace-buffer-size")]
+    pub trace_buffer_size_kib: Option<u64>,
+
+    /// trace subsystem to use. "mem" subsystem is set by default.
+    #[argh(option, default = "Default::default()")]
+    pub tracing_subsystem: TracerType,
+
+    /// if true enables all the needed trace events. And at the end it restores
+    /// the values of those events.
+    /// If false, assumes that user has setup the needed trace events.
+    #[argh(option, default = "true")]
+    pub setup_tracing: bool,
+
+    /// if specified, works on a tracing instance (like /sys/kernel/tracing/instance/my_instance)
+    /// rather than using on shared global instance (i.e. /sys/kernel/tracing)."
+    #[argh(
+        option,
+        default = "Some(\"prefetch\".to_string())",
+        from_str_fn(parse_tracing_instance)
+    )]
+    pub tracing_instance: Option<String>,
+}
+
+/// Type of tracing subsystem to use.
+#[derive(Deserialize, Clone, Eq, PartialEq, Debug)]
+pub enum TracerType {
+    /// mem tracing subsystem relies on when a file's in-memory page gets added to the fs cache.
+    Mem,
+}
+
+impl FromStr for TracerType {
+    type Err = Error;
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        Ok(match s.to_lowercase().as_str() {
+            "mem" => Self::Mem,
+            _ => {
+                return Err(Error::InvalidArgs {
+                    arg_name: "tracing_subsystem".to_owned(),
+                    arg_value: s.to_owned(),
+                    error: "unknown value".to_owned(),
+                })
+            }
+        })
+    }
+}
+
+impl Default for TracerType {
+    fn default() -> Self {
+        Self::Mem
+    }
+}
+
+#[derive(Eq, PartialEq, Debug, Default, FromArgs)]
+/// Prefetch data from the recorded file.
+#[argh(subcommand, name = "replay")]
+pub struct ReplayArgs {
+    /// file path from where the records will be read
+    #[argh(option, default = "default_path()")]
+    pub path: PathBuf,
+
+    /// IO depth. Number of IO that can go in parallel.
+    #[argh(option, long = "io-depth", default = "DEFAULT_IO_DEPTH")]
+    pub io_depth: u16,
+
+    /// max number of open fds to cache
+    #[argh(option, arg_name = "max-fds", default = "DEFAULT_MAX_FDS")]
+    pub max_fds: u16,
+
+    /// if true, command exits on encountering any error.
+    ///
+    /// This defaults to false as there is not harm prefetching if we encounter
+    /// non-fatal errors.
+    #[argh(option, default = "DEFAULT_EXIT_ON_ERROR")]
+    pub exit_on_error: bool,
+
+    /// file path from where the prefetch config file will be read
+    #[argh(option, default = "PathBuf::new()")]
+    pub config_path: PathBuf,
+}
+
+/// dump records file in given format
+#[derive(Eq, PartialEq, Debug, Default, FromArgs)]
+#[argh(subcommand, name = "dump")]
+pub struct DumpArgs {
+    /// file path from where the records will be read
+    #[argh(option)]
+    pub path: PathBuf,
+    /// output format. One of json or csv.
+    /// Note: In csv format, few fields are excluded from the output.
+    #[argh(option)]
+    pub format: OutputFormat,
+}
+
+#[derive(Deserialize, Eq, PartialEq, Debug)]
+pub enum OutputFormat {
+    Json,
+    Csv,
+}
+
+impl FromStr for OutputFormat {
+    type Err = Error;
+    fn from_str(s: &str) -> std::result::Result<Self, Self::Err> {
+        Ok(match s.to_lowercase().as_str() {
+            "csv" => Self::Csv,
+            "json" => Self::Json,
+            _ => {
+                return Err(Error::InvalidArgs {
+                    arg_name: "format".to_owned(),
+                    arg_value: s.to_owned(),
+                    error: "unknown value".to_owned(),
+                })
+            }
+        })
+    }
+}
+
+impl Default for OutputFormat {
+    fn default() -> Self {
+        Self::Json
+    }
+}
+
+/// Build args struct from command line arguments
+pub fn args_from_env() -> MainArgs {
+    argh::from_env()
+}
diff --git a/init/libprefetch/prefetch/src/error.rs b/init/libprefetch/prefetch/src/error.rs
new file mode 100644
index 0000000..8dd938a
--- /dev/null
+++ b/init/libprefetch/prefetch/src/error.rs
@@ -0,0 +1,187 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use thiserror::Error;
+
+use crate::{format::FileId, InodeInfo};
+
+/// Enumerates all possible errors returned by this library.
+#[derive(Debug, Error)]
+pub enum Error {
+    /// Represents a failure to open a file.
+    #[error("Open error: {path}: {source}")]
+    Open {
+        /// The IO error
+        source: std::io::Error,
+        /// Path on which the operation failed.
+        path: String,
+    },
+
+    /// Represents a failure to create a file.
+    #[error("Create error. {path} {source}")]
+    Create {
+        /// The IO error
+        source: std::io::Error,
+        /// Path on which the operation failed.
+        path: String,
+    },
+
+    /// Represents a failure to read trace file.
+    #[error("Read error. {error}")]
+    Read {
+        /// Detailed error message.
+        error: String,
+    },
+
+    /// Represents a failure to write to a file.
+    #[error("Write error. {source}")]
+    Write {
+        /// The IO error
+        source: std::io::Error,
+
+        /// file path
+        path: String,
+    },
+
+    /// Represents a failure to delete a file.
+    #[error("Delete error. {path} {source}")]
+    Delete {
+        /// The IO error
+        source: std::io::Error,
+        /// Path on which the operation failed.
+        path: String,
+    },
+
+    /// Represents a failure to stat a file.
+    #[error("Stat error. {path} {source}")]
+    Stat {
+        /// The IO error
+        source: std::io::Error,
+        /// Path on which the operation failed.
+        path: String,
+    },
+
+    /// Represents a failure to stat a file.
+    #[error("clone failed. {id} {source}")]
+    FileClone {
+        /// The IO error
+        source: std::io::Error,
+        /// File id for which we could not clone the file.
+        id: FileId,
+    },
+
+    /// Represents a failure to mmap a file.
+    #[error("mmap failed. {path} {error}")]
+    Mmap {
+        /// Detailed error message.
+        error: String,
+        /// Path on which the operation failed.
+        path: String,
+    },
+
+    /// Represents a failure to munmap a file.
+    #[error("munmap failed. {length} {error}")]
+    Munmap {
+        /// Detailed error message.
+        error: String,
+        /// Size of file which this munmap failed
+        length: usize,
+    },
+
+    /// Represents all other cases of `std::io::Error`.
+    ///
+    #[error(transparent)]
+    IoError(
+        /// The IO error
+        #[from]
+        std::io::Error,
+    ),
+
+    /// Represents a failure to map FileId to path
+    ///
+    #[error("Failed to map id to path: {id}")]
+    IdNoFound {
+        /// File id for which path lookup failed.
+        id: FileId,
+    },
+
+    /// Indicates that the file is skipped for prefetching
+    /// because it is in the exclude files list.
+    ///
+    #[error("Skipped prefetching file from path: {path}")]
+    SkipPrefetch {
+        /// Path to file for which prefetching is skipped.
+        path: String,
+    },
+
+    /// Represents spurious InodeInfo or missing Record.
+    ///
+    #[error(
+        "Stale inode(s) info found.\n\
+            missing_file_ids: {missing_file_ids:#?}\n\
+            stale_inodes: {stale_inodes:#?} \n\
+            missing_paths:{missing_paths:#?}"
+    )]
+    StaleInode {
+        /// FileIds for which InodeInfo is missing.
+        missing_file_ids: Vec<FileId>,
+
+        /// InodeInfos for which no records exist.
+        stale_inodes: Vec<InodeInfo>,
+
+        /// InodeInfos in which no paths were found.
+        missing_paths: Vec<InodeInfo>,
+    },
+
+    /// Represents a failure to serialize records file.
+    #[error("Serialize error: {error}")]
+    Serialize {
+        /// Detailed error message.
+        error: String,
+    },
+
+    /// Represents a failure to deserialize records file.
+    #[error("Deserialize error: {error}")]
+    Deserialize {
+        /// Detailed error message.
+        error: String,
+    },
+
+    /// Represents a failure from thread pool.
+    #[error("Thread pool error: {error}")]
+    ThreadPool {
+        /// Detailed error message.
+        error: String,
+    },
+
+    /// Represents a failure to setup file.
+    #[error("Failed to setup prefetch: {error}")]
+    Custom {
+        /// Detailed error message.
+        error: String,
+    },
+
+    /// Represents a failure to parse args.
+    #[error("Failed to parse arg:{arg_name} value:{arg_value} error:{error}")]
+    InvalidArgs {
+        /// Arg name.
+        arg_name: String,
+
+        /// Arg value.
+        arg_value: String,
+
+        /// Detailed error message.
+        error: String,
+    },
+}
diff --git a/init/libprefetch/prefetch/src/format.rs b/init/libprefetch/prefetch/src/format.rs
new file mode 100644
index 0000000..ac89a74
--- /dev/null
+++ b/init/libprefetch/prefetch/src/format.rs
@@ -0,0 +1,823 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::cmp::{max, min};
+use std::collections::{BTreeMap, HashMap, HashSet};
+use std::fmt;
+use std::fmt::Display;
+use std::fs::{File, Metadata, OpenOptions};
+use std::hash::Hash;
+use std::io::Write;
+use std::ops::{Deref, DerefMut};
+use std::os::unix::fs::MetadataExt;
+use std::time::SystemTime;
+
+use crc32fast::Hasher;
+use log::debug;
+use regex::Regex;
+use serde::Deserializer;
+use serde::Serialize;
+use serde::{Deserialize, Serializer};
+
+use crate::error::Error;
+
+static MAGIC_UUID: [u8; 16] = [
+    0x10, 0x54, 0x3c, 0xb8, 0x60, 0xdb, 0x49, 0x45, 0xa1, 0xd5, 0xde, 0xa7, 0xd2, 0x3b, 0x05, 0x49,
+];
+static MAJOR_VERSION: u16 = 0;
+static MINOR_VERSION: u16 = 1;
+
+/// Represents inode number which is unique within a filesystem.
+pub(crate) type InodeNumber = u64;
+
+/// Represents device number which is unique for given block device.
+pub(crate) type DeviceNumber = u64;
+
+/// Convenience name for string that represents a path.
+pub(crate) type PathString = String;
+
+/// Represents unique file id across filesystems.
+#[derive(Clone, Debug, Deserialize, Eq, Hash, Default, PartialEq, PartialOrd, Ord, Serialize)]
+pub struct FileId(pub u64);
+
+impl Display for FileId {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.0.fmt(f)
+    }
+}
+
+fn serialize_hashmap<S, K: Ord + Serialize + Clone, V: Serialize + Clone>(
+    value: &HashMap<K, V>,
+    serializer: S,
+) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    let mut btree = BTreeMap::new();
+    for (k, v) in value {
+        btree.insert(k.clone(), v.clone());
+    }
+    btree.serialize(serializer)
+}
+
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+pub(crate) struct SerializableHashMap<
+    K: Ord + Serialize + Clone + Hash + PartialEq,
+    V: Serialize + Clone,
+> {
+    #[serde(serialize_with = "serialize_hashmap")]
+    pub map: HashMap<K, V>,
+}
+
+impl<K, V> Deref for SerializableHashMap<K, V>
+where
+    K: Ord + Serialize + Clone + Hash + PartialEq,
+    V: Serialize + Clone,
+{
+    type Target = HashMap<K, V>;
+    fn deref(&self) -> &Self::Target {
+        &self.map
+    }
+}
+
+impl<K, V> DerefMut for SerializableHashMap<K, V>
+where
+    K: Ord + Serialize + Clone + Hash + PartialEq,
+    V: Serialize + Clone,
+{
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.map
+    }
+}
+
+/// The InodeInfo is unique per (device, inode) combination. It is
+/// used to verify that we are prefetching a file for which we generated
+/// the records for.
+/// `Record` refers to this information with a unique `FileId`.
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+pub struct InodeInfo {
+    // Inode number of the file.
+    pub(crate) inode_number: InodeNumber,
+
+    // File size in bytes.
+    pub(crate) file_size: u64,
+
+    // Helps to get to a file from a Record. The field is used to get to the file
+    // that needs to be prefetched.
+    //
+    // This struct is built by getting data from trace lines and querying filesystem
+    // for other fields about the file/inode.
+    //
+    // One instance per file to be prefetched. A file/inode can have multiple paths.
+    // We store multiple paths so that we can still get to it if some of the
+    // paths get deleted.
+    //
+    // See comments for `Record`.
+    #[serde(deserialize_with = "check_inode_info_paths")]
+    pub(crate) paths: Vec<PathString>,
+
+    // Block device number on which the file is located.
+    pub(crate) device_number: DeviceNumber,
+}
+
+impl InodeInfo {
+    /// Returns InodeInfo.
+    pub fn new(
+        inode_number: InodeNumber,
+        file_size: u64,
+        paths: Vec<String>,
+        device_number: DeviceNumber,
+    ) -> Self {
+        Self { inode_number, file_size, paths, device_number }
+    }
+}
+
+// Helps us check block alignment.
+//
+// A records file can have multiple FsInfos.
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+pub struct FsInfo {
+    // This is filesystem block size and is not underlying device's block size
+    pub(crate) block_size: u64,
+}
+
+/// Prefetch record.
+/// Each record translates to one filesystem `read()` request.
+///
+/// Tracer builds `Record` by parsing trace lines or by querying filesystem.
+///
+/// Multiple `Record`s can belong to a single InodeInfo. For example if there were two
+/// reads for file `/data/my.apk` which is assigned FileId 10 at offsets 0 and 8k of length
+/// 1 byte each then we will have two `Records` in `RecordsFile` that look like
+/// `Record {file_id: 10, offset: 0, length: 1, timestamp: t1}`
+/// `Record {file_id: 10, offset: 8192, length: 1, timestamp: t2}`
+#[derive(Clone, Debug, Default, Deserialize, Eq, PartialEq, Serialize)]
+pub struct Record {
+    /// Points to the file that should be fetched./ file_id is unique per `InodeInfo`
+    /// in a `RecordsFile`
+    pub file_id: FileId,
+
+    /// start offset to fetch data from. This is FsInfo.block_size aligned.
+    pub offset: u64,
+
+    /// length of the read. This is generally rounded up to Fs.Info.block_size
+    /// except when the rounding up crosses `InodeInfo.file_size`
+    pub length: u64,
+
+    /// Timestamp in nanoseconds since the start when the data was loaded.
+    pub timestamp: u64,
+}
+
+impl Record {
+    /// Returns a new record if two records belong to same file and overlap.
+    fn overlaps(&self, other: &Self) -> Option<Self> {
+        if self.file_id == other.file_id {
+            let self_start = self.offset;
+            let self_end = self.offset + self.length;
+            let other_start = other.offset;
+            let other_end = other.offset + other.length;
+
+            if (self_start <= other_end) && (self_end >= other_start) {
+                let offset = min(self_start, other_start);
+                let length = max(self_end, other_end) - offset;
+                return Some(Self {
+                    file_id: self.file_id.clone(),
+                    offset,
+                    length,
+                    timestamp: min(self.timestamp, other.timestamp),
+                });
+            }
+        }
+        None
+    }
+}
+
+fn group_record_by_file_id(records: Vec<Record>) -> Vec<Record> {
+    let mut map: HashMap<FileId, BTreeMap<u64, Record>> = HashMap::new();
+
+    for record in &records {
+        let recs = map.entry(record.file_id.clone()).or_default();
+        recs.entry(record.offset).or_insert_with(|| record.clone());
+    }
+
+    let mut grouped = vec![];
+    for record in &records {
+        if let Some(inode) = map.get(&record.file_id) {
+            for rec in inode.values() {
+                grouped.push(rec.clone());
+            }
+        }
+        let _ = map.remove(&record.file_id);
+    }
+
+    grouped
+}
+
+/// When records are coalesced, because their file ids match and IO offsets overlap, the least
+/// timestamp of the coalesced records is retained.
+pub(crate) fn coalesce_records(records: Vec<Record>, group_by_file_id: bool) -> Vec<Record> {
+    let records = if group_by_file_id { group_record_by_file_id(records) } else { records };
+
+    let mut coalesced = vec![];
+    let mut current: Option<Record> = None;
+    for r in records {
+        current = match current {
+            None => Some(r),
+            Some(c) => {
+                let merged = c.overlaps(&r);
+                match merged {
+                    None => {
+                        coalesced.push(c);
+                        Some(r)
+                    }
+                    Some(m) => Some(m),
+                }
+            }
+        }
+    }
+    if let Some(r) = current {
+        coalesced.push(r);
+    }
+    coalesced
+}
+
+// Records file header.
+#[derive(Clone, Debug, Deserialize, Eq, PartialEq, Serialize)]
+pub struct Header {
+    /// magic number as uuid to identify the header/format.
+    #[serde(deserialize_with = "check_magic")]
+    magic: [u8; 16],
+
+    // major version number.
+    #[serde(deserialize_with = "check_major_number")]
+    major_number: u16,
+
+    // minor version number.
+    #[serde(deserialize_with = "check_minor_number")]
+    minor_number: u16,
+
+    /// timestamp when the records file was generated.
+    date: SystemTime,
+
+    /// Checksum of the `RecordsFile` with `digest` being empty vector.
+    digest: u32,
+}
+
+fn check_version_number<'de, D>(
+    deserializer: D,
+    expected: u16,
+    version_type: &str,
+) -> Result<u16, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let found = u16::deserialize(deserializer)?;
+    if expected != found {
+        return Err(serde::de::Error::custom(format!(
+            "Failed to parse {} version. Expected: {} Found: {}",
+            version_type, expected, found
+        )));
+    }
+    Ok(found)
+}
+
+fn check_major_number<'de, D>(deserializer: D) -> Result<u16, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    check_version_number(deserializer, MAJOR_VERSION, "major")
+}
+
+fn check_minor_number<'de, D>(deserializer: D) -> Result<u16, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    check_version_number(deserializer, MINOR_VERSION, "minor")
+}
+
+fn check_magic<'de, D>(deserializer: D) -> Result<[u8; 16], D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let found: [u8; 16] = <[u8; 16]>::deserialize(deserializer)?;
+    if found != MAGIC_UUID {
+        return Err(serde::de::Error::custom(format!(
+            "Failed to parse magic number. Expected: {:?} Found: {:?}",
+            MAGIC_UUID, found
+        )));
+    }
+    Ok(found)
+}
+
+fn check_inode_info_paths<'de, D>(deserializer: D) -> Result<Vec<PathString>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let parsed: Vec<PathString> = Vec::deserialize(deserializer)?;
+    if parsed.is_empty() {
+        return Err(serde::de::Error::custom("No paths found for in InodeInfo"));
+    }
+    Ok(parsed)
+}
+
+// Helper inner struct of RecordsFile meant to verify checksum.
+#[derive(Clone, Debug, Default, Deserialize, Serialize, Eq, PartialEq)]
+pub(crate) struct RecordsFileInner {
+    // One instance per mounted block device.
+    pub(crate) filesystems: SerializableHashMap<DeviceNumber, FsInfo>,
+
+    /// Helps to get to a file path from a given `FileId`.
+    /// One instance per file to be prefetched.
+    pub(crate) inode_map: SerializableHashMap<FileId, InodeInfo>,
+
+    /// Helps to get to a file and offset to be replayed..
+    ///
+    // The records are chronologically arranged meaning the data that
+    // needs first is at the beginning of the vector and the data that
+    // needs last is at the end.
+    //
+    // One instance per part of the file that needs to be prefetched.
+    pub records: Vec<Record>,
+}
+
+/// Deserialized form of records file.
+#[derive(Clone, Debug, Default, Deserialize, Serialize, Eq, PartialEq)]
+#[serde(remote = "Self")]
+pub struct RecordsFile {
+    /// Helps the prefetch tool to parse rest of the file
+    pub header: Header,
+
+    /// Helps the prefetch tool to verify checksum.
+    pub(crate) inner: RecordsFileInner,
+}
+
+impl RecordsFile {
+    /// Given file id, looks up path of the file and returns open File handle.
+    pub fn open_file(&self, id: FileId, exclude_files_regex: &[Regex]) -> Result<File, Error> {
+        if let Some(inode) = self.inner.inode_map.get(&id) {
+            let path = inode.paths.first().unwrap();
+
+            for regex in exclude_files_regex {
+                if regex.is_match(path) {
+                    return Err(Error::SkipPrefetch { path: path.to_owned() });
+                }
+            }
+            debug!("Opening {} file {}", id.0, path);
+            OpenOptions::new()
+                .read(true)
+                .write(false)
+                .open(path)
+                .map_err(|source| Error::Open { source, path: path.to_owned() })
+        } else {
+            Err(Error::IdNoFound { id })
+        }
+    }
+
+    /// Inserts given record in RecordsFile
+    pub fn insert_record(&mut self, records: Record) {
+        self.inner.records.push(records);
+    }
+
+    /// Inserts given InodeInfo into in RecordsFile.
+    pub fn insert_or_update_inode_info(&mut self, id: FileId, info: InodeInfo) {
+        if let Some(inode) = self.inner.inode_map.get_mut(&id) {
+            if let Some(first_path) = info.paths.first() {
+                inode.paths.push(first_path.clone());
+            }
+        } else {
+            self.inner.inode_map.insert(id, info);
+        }
+    }
+
+    /// Verifies the integrity of records file.
+    ///
+    /// check saves us from serializing a improperly built record file or replaying an inconsistent
+    /// `RecordFile`.
+    ///
+    /// Note: check only works on the `RecordsFile` and doesn't access filesystem. We limit the
+    /// scope so that we avoid issuing filesystem operations(directory lookup, stats) twice - once
+    /// during check and once during replaying.
+    pub fn check(&self) -> Result<(), Error> {
+        let mut unique_files = HashSet::new();
+        let mut missing_file_ids = vec![];
+
+        for record in &self.inner.records {
+            if !self.inner.inode_map.contains_key(&record.file_id) {
+                missing_file_ids.push(record.file_id.clone());
+            }
+            unique_files.insert(record.file_id.clone());
+        }
+
+        let mut stale_inodes = vec![];
+        let mut missing_paths = vec![];
+        for (file_id, inode_info) in &self.inner.inode_map.map {
+            if inode_info.paths.is_empty() {
+                missing_paths.push(inode_info.clone());
+            }
+            if !unique_files.contains(file_id) {
+                stale_inodes.push(inode_info.clone());
+            }
+        }
+
+        if !stale_inodes.is_empty() || !missing_paths.is_empty() || !missing_file_ids.is_empty() {
+            return Err(Error::StaleInode { stale_inodes, missing_paths, missing_file_ids });
+        }
+
+        Ok(())
+    }
+
+    /// Builds InodeInfo from args and inserts inode info in RecordsFile.
+    pub fn insert_or_update_inode(&mut self, id: FileId, stat: &Metadata, path: PathString) {
+        self.insert_or_update_inode_info(
+            id,
+            InodeInfo {
+                inode_number: stat.ino(),
+                file_size: stat.len(),
+                paths: vec![path],
+                device_number: stat.dev(),
+            },
+        )
+    }
+
+    /// Serialize records in the form of csv.
+    pub fn serialize_records_to_csv(&self, writer: &mut dyn Write) -> Result<(), Error> {
+        let mut wtr = csv::Writer::from_writer(writer);
+
+        #[derive(Serialize)]
+        struct TempRecord<'a> {
+            timestamp: u64,
+            file: &'a PathString,
+            offset: u64,
+            length: u64,
+            file_size: u64,
+        }
+
+        for record in &self.inner.records {
+            if let Some(inode_info) = self.inner.inode_map.get(&record.file_id) {
+                let mut inode_info = inode_info.clone();
+                inode_info.paths.sort();
+
+                if let Some(first_path) = inode_info.paths.first().cloned() {
+                    // Clone the &String inside Option
+                    let record = TempRecord {
+                        timestamp: record.timestamp,
+                        file: &first_path, // Now you have &String
+                        offset: record.offset,
+                        length: record.length,
+                        file_size: inode_info.file_size,
+                    };
+                    wtr.serialize(&record)
+                        .map_err(|e| Error::Serialize { error: e.to_string() })?;
+                }
+            }
+        }
+        wtr.flush()?;
+        Ok(())
+    }
+
+    fn compute_digest(&mut self) -> Result<u32, Error> {
+        self.header.digest = Default::default();
+        let serialized = serde_cbor::to_vec(self)
+            .map_err(|source| Error::Serialize { error: source.to_string() })?;
+
+        let mut hasher = Hasher::new();
+        hasher.update(&serialized);
+
+        Ok(hasher.finalize())
+    }
+
+    /// Convenience wrapper around serialize that adds checksum/digest to the file
+    /// to verify file consistency during replay/deserialize.
+    pub fn add_checksum_and_serialize(&mut self) -> Result<Vec<u8>, Error> {
+        self.header.digest = self.compute_digest()?;
+
+        serde_cbor::to_vec(self).map_err(|source| Error::Serialize { error: source.to_string() })
+    }
+}
+
+impl Default for Header {
+    fn default() -> Self {
+        Self {
+            major_number: MAJOR_VERSION,
+            minor_number: MINOR_VERSION,
+            date: SystemTime::now(),
+            digest: 0,
+            magic: MAGIC_UUID,
+        }
+    }
+}
+
+// Wrapper around deserialize to check any inconsistencies in the file format.
+impl<'de> Deserialize<'de> for RecordsFile {
+    fn deserialize<D>(deserializer: D) -> std::result::Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let rf = Self::deserialize(deserializer)?;
+
+        rf.check().map_err(|e| {
+            serde::de::Error::custom(format!("failed to validate records file: {}", e))
+        })?;
+
+        let mut zero_digest = rf.clone();
+        zero_digest.header.digest = 0;
+        let digest =
+            zero_digest.compute_digest().map_err(|e| serde::de::Error::custom(format!("{}", e)))?;
+
+        if digest != rf.header.digest {
+            return Err(serde::de::Error::custom(format!(
+                "file consistency check failed. Expected: {}. Found: {}",
+                digest, rf.header.digest
+            )));
+        }
+
+        Ok(rf)
+    }
+}
+
+// Wrapper around serialize to check any inconsistencies in the file format before serializing
+impl Serialize for RecordsFile {
+    fn serialize<S>(&self, serializer: S) -> std::result::Result<S::Ok, S::Error>
+    where
+        S: Serializer,
+    {
+        self.check().map(|_| self).map_err(|e| {
+            serde::ser::Error::custom(format!("failed to validate records file: {}", e))
+        })?;
+        Self::serialize(self, serializer)
+    }
+}
+
+#[cfg(test)]
+pub mod tests {
+
+    use std::assert_eq;
+
+    use super::*;
+
+    #[test]
+    fn test_major_version_mismatch() {
+        let mut rf = RecordsFile::default();
+
+        rf.header.major_number += 1;
+
+        let serialized: Result<RecordsFile, serde_cbor::Error> =
+            serde_cbor::from_slice(&serde_cbor::to_vec(&rf).unwrap());
+
+        assert_eq!(
+            serialized.unwrap_err().to_string(),
+            format!(
+                "Failed to parse major version. Expected: {} Found: {}",
+                MAJOR_VERSION,
+                MAJOR_VERSION + 1
+            )
+        );
+    }
+
+    #[test]
+    fn test_minor_version_mismatch() {
+        let mut rf = RecordsFile::default();
+
+        rf.header.minor_number += 1;
+
+        let serialized: Result<RecordsFile, serde_cbor::Error> =
+            serde_cbor::from_slice(&serde_cbor::to_vec(&rf).unwrap());
+
+        assert_eq!(
+            serialized.unwrap_err().to_string(),
+            format!(
+                "Failed to parse minor version. Expected: {} Found: {}",
+                MINOR_VERSION,
+                MINOR_VERSION + 1
+            )
+        );
+    }
+
+    #[test]
+    fn deserialize_inode_info_without_path() {
+        let inode = InodeInfo { inode_number: 1, file_size: 10, paths: vec![], device_number: 1 };
+        let serialized = serde_cbor::to_vec(&inode).unwrap();
+        let deserialized: Result<InodeInfo, serde_cbor::Error> =
+            serde_cbor::from_slice(&serialized);
+        assert_eq!(
+            deserialized.unwrap_err().to_string(),
+            "No paths found for in InodeInfo".to_owned()
+        );
+    }
+    #[test]
+    fn test_serialize_records_to_csv() {
+        let mut rf = RecordsFile::default();
+        let file_count = 4;
+        for i in 0..file_count {
+            rf.insert_or_update_inode_info(
+                FileId(i),
+                InodeInfo {
+                    inode_number: i,
+                    file_size: i * 10,
+                    paths: vec![format!("/hello/{}", i)],
+                    device_number: i + 10,
+                },
+            )
+        }
+        for i in 0..10 {
+            rf.insert_record(Record {
+                file_id: FileId(i % file_count),
+                offset: i * 3,
+                length: i + 4,
+                timestamp: i * file_count,
+            });
+        }
+
+        let mut buf = vec![];
+        rf.serialize_records_to_csv(&mut buf).unwrap();
+
+        let data = String::from_utf8(buf).unwrap();
+        assert_eq!(
+            data,
+            "timestamp,file,offset,length,file_size\n\
+            0,/hello/0,0,4,0\n\
+            4,/hello/1,3,5,10\n\
+            8,/hello/2,6,6,20\n\
+            12,/hello/3,9,7,30\n\
+            16,/hello/0,12,8,0\n\
+            20,/hello/1,15,9,10\n\
+            24,/hello/2,18,10,20\n\
+            28,/hello/3,21,11,30\n\
+            32,/hello/0,24,12,0\n\
+            36,/hello/1,27,13,10\n"
+        );
+    }
+
+    fn new_record(file: u64, offset: u64, length: u64, timestamp: u64) -> Record {
+        Record { file_id: FileId(file), offset, length, timestamp }
+    }
+
+    #[test]
+    fn test_coalesced_without_group() {
+        let non_coalescable_same_inode =
+            vec![new_record(1, 2, 3, 4), new_record(1, 6, 3, 5), new_record(1, 10, 3, 6)];
+        assert_eq!(
+            coalesce_records(non_coalescable_same_inode.clone(), false),
+            non_coalescable_same_inode
+        );
+
+        let non_coalescable_different_inode =
+            vec![new_record(1, 2, 3, 4), new_record(2, 5, 3, 5), new_record(3, 8, 3, 6)];
+        assert_eq!(
+            coalesce_records(non_coalescable_different_inode.clone(), false),
+            non_coalescable_different_inode
+        );
+
+        let some_coalesced =
+            vec![new_record(1, 2, 3, 4), new_record(1, 5, 3, 5), new_record(3, 8, 3, 6)];
+        assert_eq!(
+            coalesce_records(some_coalesced, false),
+            vec![new_record(1, 2, 6, 4), new_record(3, 8, 3, 6),]
+        );
+
+        let coalesced_into_one =
+            vec![new_record(1, 2, 3, 4), new_record(1, 5, 3, 5), new_record(1, 8, 3, 6)];
+        assert_eq!(coalesce_records(coalesced_into_one, false), vec![new_record(1, 2, 9, 4)]);
+
+        let no_grouping_or_coalescing =
+            vec![new_record(1, 2, 3, 4), new_record(3, 8, 3, 5), new_record(1, 5, 3, 6)];
+        assert_eq!(
+            coalesce_records(no_grouping_or_coalescing, false),
+            vec![new_record(1, 2, 3, 4), new_record(3, 8, 3, 5), new_record(1, 5, 3, 6),]
+        );
+    }
+
+    #[test]
+    fn test_coalesced_with_grouping() {
+        let non_coalescable_same_inode =
+            vec![new_record(1, 2, 3, 4), new_record(1, 6, 3, 5), new_record(1, 10, 3, 6)];
+        assert_eq!(
+            coalesce_records(non_coalescable_same_inode.clone(), true),
+            non_coalescable_same_inode
+        );
+
+        let non_coalescable_different_inode =
+            vec![new_record(1, 2, 3, 4), new_record(2, 5, 3, 5), new_record(3, 8, 3, 6)];
+        assert_eq!(
+            coalesce_records(non_coalescable_different_inode.clone(), true),
+            non_coalescable_different_inode
+        );
+
+        let some_coalesced =
+            vec![new_record(1, 2, 3, 4), new_record(1, 5, 3, 5), new_record(3, 8, 3, 6)];
+        assert_eq!(
+            coalesce_records(some_coalesced, true),
+            vec![new_record(1, 2, 6, 4), new_record(3, 8, 3, 6),]
+        );
+
+        let coalesced_into_one =
+            vec![new_record(1, 2, 3, 4), new_record(1, 5, 3, 5), new_record(1, 8, 3, 6)];
+        assert_eq!(coalesce_records(coalesced_into_one, true), vec![new_record(1, 2, 9, 4)]);
+
+        let some_grouped_coalesced =
+            vec![new_record(1, 2, 3, 4), new_record(3, 8, 3, 5), new_record(1, 5, 3, 6)];
+        assert_eq!(
+            coalesce_records(some_grouped_coalesced, true),
+            vec![new_record(1, 2, 6, 4), new_record(3, 8, 3, 5),]
+        );
+    }
+
+    #[test]
+    fn check_missing_records() {
+        let mut rf = RecordsFile::default();
+        rf.inner.inode_map.insert(
+            FileId(0),
+            InodeInfo {
+                inode_number: 0,
+                file_size: 1,
+                paths: vec!["hello".to_owned()],
+                device_number: 2,
+            },
+        );
+        rf.insert_record(Record { file_id: FileId(0), offset: 10, length: 20, timestamp: 30 });
+
+        rf.inner.inode_map.insert(
+            FileId(1),
+            InodeInfo {
+                inode_number: 1,
+                file_size: 2,
+                paths: vec!["world".to_owned()],
+                device_number: 3,
+            },
+        );
+        let e = rf.check().unwrap_err();
+        assert_eq!(
+            e.to_string(),
+            "Stale inode(s) info found.\n\
+                missing_file_ids: []\n\
+                stale_inodes: [\n    \
+                    InodeInfo {\n        \
+                        inode_number: 1,\n        \
+                        file_size: 2,\n        \
+                        paths: [\n            \"world\",\n        ],\n        \
+                        device_number: 3,\n    },\n] \n\
+                missing_paths:[]"
+        );
+    }
+
+    #[test]
+    fn check_missing_file() {
+        let mut rf = RecordsFile::default();
+        rf.inner.inode_map.insert(
+            FileId(0),
+            InodeInfo {
+                inode_number: 0,
+                file_size: 1,
+                paths: vec!["hello".to_owned()],
+                device_number: 2,
+            },
+        );
+        rf.insert_record(Record { file_id: FileId(0), offset: 10, length: 20, timestamp: 30 });
+        rf.insert_record(Record { file_id: FileId(1), offset: 10, length: 20, timestamp: 30 });
+
+        let e = rf.check().unwrap_err();
+        assert_eq!(
+            e.to_string(),
+            "Stale inode(s) info found.\n\
+                missing_file_ids: [\n    \
+                    FileId(\n        1,\n    ),\n]\n\
+                stale_inodes: [] \n\
+                missing_paths:[]"
+        );
+    }
+
+    #[test]
+    fn check_missing_paths() {
+        let mut rf = RecordsFile::default();
+        rf.inner.inode_map.insert(
+            FileId(0),
+            InodeInfo { inode_number: 0, file_size: 1, paths: vec![], device_number: 2 },
+        );
+        rf.insert_record(Record { file_id: FileId(0), offset: 10, length: 20, timestamp: 30 });
+
+        let e = rf.check().unwrap_err();
+        assert_eq!(
+            e.to_string(),
+            "Stale inode(s) info found.\n\
+                missing_file_ids: []\n\
+                stale_inodes: [] \n\
+                missing_paths:[\n    \
+                    InodeInfo {\n        \
+                        inode_number: 0,\n        \
+                        file_size: 1,\n        \
+                        paths: [],\n        \
+                        device_number: 2,\n    },\n]"
+        );
+    }
+}
diff --git a/init/libprefetch/prefetch/src/lib.rs b/init/libprefetch/prefetch/src/lib.rs
new file mode 100644
index 0000000..4b56b13
--- /dev/null
+++ b/init/libprefetch/prefetch/src/lib.rs
@@ -0,0 +1,186 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! A library to prefetch files on the file system to optimize startup times
+//!
+
+mod args;
+mod error;
+mod format;
+mod replay;
+mod tracer;
+
+use std::fs::File;
+use std::fs::OpenOptions;
+use std::io;
+use std::io::Write;
+use std::os::unix::fs::PermissionsExt;
+use std::string::ToString;
+use std::thread;
+use std::time::Duration;
+
+#[cfg(target_os = "android")]
+use log::Level;
+#[cfg(target_os = "linux")]
+use log::LevelFilter;
+
+pub use args::args_from_env;
+use args::OutputFormat;
+pub use args::ReplayArgs;
+pub use args::{DumpArgs, MainArgs, RecordArgs, SubCommands};
+pub use error::Error;
+pub use format::FileId;
+pub use format::InodeInfo;
+pub use format::Record;
+pub use format::RecordsFile;
+use log::info;
+#[cfg(target_os = "android")]
+use log::warn;
+pub use replay::Replay;
+pub use tracer::nanoseconds_since_boot;
+
+#[cfg(target_os = "android")]
+use rustutils::system_properties;
+#[cfg(target_os = "android")]
+use rustutils::system_properties::error::PropertyWatcherError;
+#[cfg(target_os = "android")]
+use rustutils::system_properties::PropertyWatcher;
+
+#[cfg(target_os = "android")]
+fn wait_for_property_true(property_name: &str) -> Result<(), PropertyWatcherError> {
+    let mut prop = PropertyWatcher::new(property_name)?;
+    loop {
+        prop.wait(None)?;
+        if system_properties::read_bool(property_name, false)? {
+            break;
+        }
+    }
+    Ok(())
+}
+
+/// Records prefetch data for the given configuration
+pub fn record(args: &RecordArgs) -> Result<(), Error> {
+    let (mut tracer, exit_tx) = tracer::Tracer::create(
+        args.trace_buffer_size_kib,
+        args.tracing_subsystem.clone(),
+        args.tracing_instance.clone(),
+        args.setup_tracing,
+    )?;
+    let duration = Duration::from_secs(args.duration as u64);
+
+    let thd = thread::spawn(move || {
+        if !duration.is_zero() {
+            info!("Record start - waiting for duration: {:?}", duration);
+            thread::sleep(duration);
+        } else {
+            #[cfg(target_os = "android")]
+            wait_for_property_true("sys.boot_completed").unwrap_or_else(|e| {
+                warn!("failed to wait for sys.boot_completed with error: {}", e)
+            });
+        }
+
+        // We want to unwrap here on failure to send this signal. Otherwise
+        // tracer will continue generating huge records data.
+        exit_tx.send(()).unwrap();
+    });
+
+    let mut rf = tracer.trace(args.int_path.as_ref())?;
+    thd.join()
+        .map_err(|_| Error::ThreadPool { error: "Failed to join timeout thread".to_string() })?;
+
+    let mut out_file =
+        OpenOptions::new().write(true).create(true).truncate(true).open(&args.path).map_err(
+            |source| Error::Create { source, path: args.path.to_str().unwrap().to_owned() },
+        )?;
+
+    std::fs::set_permissions(&args.path, std::fs::Permissions::from_mode(0o644))
+        .map_err(|source| Error::Create { source, path: args.path.to_str().unwrap().to_owned() })?;
+
+    out_file
+        .write_all(&rf.add_checksum_and_serialize()?)
+        .map_err(|source| Error::Write { path: args.path.to_str().unwrap().to_owned(), source })?;
+    Ok(())
+}
+
+/// Replays prefetch data for the given configuration
+pub fn replay(args: &ReplayArgs) -> Result<(), Error> {
+    let replay = Replay::new(args)?;
+    replay.replay()
+}
+
+/// Dumps prefetch data in the human readable form
+pub fn dump(args: &DumpArgs) -> Result<(), Error> {
+    let reader = File::open(&args.path)
+        .map_err(|source| Error::Open { source, path: args.path.to_str().unwrap().to_string() })?;
+    let rf: RecordsFile =
+        serde_cbor::from_reader(reader).map_err(|e| Error::Deserialize { error: e.to_string() })?;
+    match args.format {
+        OutputFormat::Json => println!(
+            "{:#}",
+            serde_json::to_string_pretty(&rf)
+                .map_err(|e| Error::Serialize { error: e.to_string() })?
+        ),
+        OutputFormat::Csv => rf.serialize_records_to_csv(&mut io::stdout())?,
+    }
+    Ok(())
+}
+
+/// An alias of android_logger::Level to use log level across android and linux.
+#[cfg(target_os = "android")]
+pub type LogLevel = Level;
+
+/// An alias of log::LevelFilter to use log level across android and linux.
+#[cfg(not(target_os = "android"))]
+pub type LogLevel = LevelFilter;
+
+/// Convenience logging initializer that is shared between the prefetch tool and c wrapper library
+#[cfg(target_os = "android")]
+pub fn init_logging(_level: LogLevel) {
+    android_logger::init_once(
+        android_logger::Config::default().with_max_level(log::LevelFilter::Info).format(
+            |f, record| {
+                write!(
+                    f,
+                    "{} prefetch_rs: {}:{} {}: {}",
+                    nanoseconds_since_boot(),
+                    record.file().unwrap_or("unknown_file"),
+                    record.line().unwrap_or(0),
+                    record.level(),
+                    record.args()
+                )
+            },
+        ),
+    )
+}
+
+/// Convenience logging initializer that is shared between the prefetch tool and c wrapper library
+#[cfg(target_os = "linux")]
+pub fn init_logging(level: LogLevel) {
+    let mut builder = env_logger::Builder::from_default_env();
+
+    builder
+        .filter(None, level)
+        .format(|buf, record| {
+            writeln!(
+                buf,
+                "{} prefetch_rs: {}:{} {}: {}",
+                nanoseconds_since_boot(),
+                record.file().unwrap_or("unknown_file"),
+                record.line().unwrap_or(0),
+                record.level(),
+                record.args()
+            )
+        })
+        .init();
+}
diff --git a/init/libprefetch/prefetch/src/main.rs b/init/libprefetch/prefetch/src/main.rs
new file mode 100644
index 0000000..046e07e
--- /dev/null
+++ b/init/libprefetch/prefetch/src/main.rs
@@ -0,0 +1,41 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! A utility wrapper around libprefetch that allows to record, replay and dump
+//! prefetch data.
+
+use log::error;
+
+use prefetch_rs::args_from_env;
+use prefetch_rs::dump;
+use prefetch_rs::init_logging;
+use prefetch_rs::record;
+use prefetch_rs::replay;
+use prefetch_rs::LogLevel;
+use prefetch_rs::MainArgs;
+use prefetch_rs::SubCommands;
+
+fn main() {
+    init_logging(LogLevel::Debug);
+    let args: MainArgs = args_from_env();
+    let ret = match &args.nested {
+        SubCommands::Record(args) => record(args),
+        SubCommands::Replay(args) => replay(args),
+        SubCommands::Dump(args) => dump(args),
+    };
+
+    if let Err(err) = ret {
+        error!("{:?} command failed: {:?}", args, err);
+    }
+}
diff --git a/init/libprefetch/prefetch/src/replay.rs b/init/libprefetch/prefetch/src/replay.rs
new file mode 100644
index 0000000..b68d747
--- /dev/null
+++ b/init/libprefetch/prefetch/src/replay.rs
@@ -0,0 +1,762 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+use std::clone::Clone;
+use std::convert::TryInto;
+use std::fmt::Display;
+use std::mem::replace;
+use std::os::unix::io::AsRawFd;
+use std::sync::Arc;
+use std::sync::Mutex;
+use std::sync::RwLock;
+use std::thread;
+
+use log::debug;
+use log::error;
+use log::warn;
+use lru_cache::LruCache;
+use nix::errno::Errno;
+use nix::fcntl::posix_fadvise;
+use regex::Regex;
+
+use crate::args::ConfigFile;
+use crate::format::Record;
+use crate::format::{FileId, RecordsFile};
+use crate::Error;
+use crate::ReplayArgs;
+use libc::{c_void, off64_t, pread64};
+use std::fs::File;
+
+const READ_SZ: usize = 1024 * 1024;
+
+struct ScopedLog<T: Display + Sized> {
+    msg: T,
+    thd_id: usize,
+}
+
+fn scoped_log<T: Display + Sized>(ctx: usize, msg: T) -> ScopedLog<T> {
+    let thd_id = ctx;
+    debug!("{} {} start", thd_id, msg);
+    ScopedLog { msg, thd_id }
+}
+
+impl<T: Display> Drop for ScopedLog<T> {
+    fn drop(&mut self) {
+        debug!("{} {} end", self.thd_id, self.msg);
+    }
+}
+
+fn readahead(
+    id: usize,
+    file: Arc<File>,
+    record: &Record,
+    buffer: &mut [u8; READ_SZ],
+) -> Result<(), Error> {
+    debug!("readahead {:?}", record);
+    let _dbg = scoped_log(id, "readahead");
+
+    let mut current_offset: off64_t = record
+        .offset
+        .try_into()
+        .map_err(|_| Error::Read { error: "Failed to convert offset".to_string() })?;
+    let mut remaining_data: usize = record
+        .length
+        .try_into()
+        .map_err(|_| Error::Read { error: "Failed to convert length".to_string() })?;
+
+    while remaining_data > 0 {
+        let read_size = std::cmp::min(READ_SZ, remaining_data);
+
+        // SAFETY: This is safe because
+        // - the file is known to exist and opened
+        // - buffer is allocated upfront and is guaranteed by the fact it comes from a mutable slice reference.
+        // - read_size is guaranteed not to exceed length of the buffer.
+        let bytes_read = unsafe {
+            pread64(file.as_raw_fd(), buffer.as_mut_ptr() as *mut c_void, read_size, current_offset)
+        };
+
+        if bytes_read == -1 {
+            return Err(Error::Read { error: format!("readahead failed: {}", Errno::last_raw()) });
+        }
+
+        if bytes_read == 0 {
+            break; // End of file reached
+        }
+
+        current_offset += bytes_read as off64_t;
+        remaining_data -= bytes_read as usize;
+    }
+
+    // TODO: Try readahead() syscall or async I/O
+    Ok(())
+}
+
+fn worker_internal(
+    id: usize,
+    state: Arc<Mutex<SharedState>>,
+    records_file: Arc<RwLock<RecordsFile>>,
+    exit_on_error: bool,
+    exclude_files_regex: Vec<Regex>,
+    buffer: &mut [u8],
+) -> Result<(), Error> {
+    loop {
+        let index = {
+            let mut state = state.lock().unwrap();
+            if state.result.is_err() {
+                return Ok(());
+            }
+            state.next_record()
+        };
+
+        let record = {
+            let rf = records_file.read().unwrap();
+            if index >= rf.inner.records.len() {
+                return Ok(());
+            }
+            rf.inner.records.get(index).unwrap().clone()
+        };
+
+        let _dbg = scoped_log(id, "record_replay");
+
+        let file = state.lock().unwrap().fds.get_mut(&record.file_id).map(|f| f.clone());
+
+        let file = match file {
+            Some(file) => file,
+            None => {
+                let file = Arc::new({
+                    let file = records_file
+                        .read()
+                        .unwrap()
+                        .open_file(record.file_id.clone(), &exclude_files_regex);
+                    if let Err(e) = file {
+                        if exit_on_error {
+                            return Err(e);
+                        } else {
+                            match e {
+                                Error::SkipPrefetch { path } => {
+                                    debug!("Skipping file during replay: {}", path);
+                                }
+                                _ => error!(
+                                    "Failed to open file id: {} with {}",
+                                    record.file_id.clone(),
+                                    e.to_string()
+                                ),
+                            }
+                            continue;
+                        }
+                    }
+
+                    let file = file.unwrap();
+                    // We do not want the filesystem be intelligent and prefetch more than what this
+                    // code is reading. So turn off prefetch.
+
+                    if let Err(e) = posix_fadvise(
+                        file.as_raw_fd(),
+                        0,
+                        0,
+                        nix::fcntl::PosixFadviseAdvice::POSIX_FADV_RANDOM,
+                    ) {
+                        warn!(
+                            "Failed to turn off filesystem read ahead for file id: {} with {}",
+                            record.file_id.clone(),
+                            e.to_string()
+                        );
+                    }
+                    file
+                });
+                let cache_file = file.clone();
+                state.lock().unwrap().fds.insert(record.file_id.clone(), cache_file);
+                file
+            }
+        };
+        if let Err(e) = readahead(id, file, &record, buffer.try_into().unwrap()) {
+            if exit_on_error {
+                return Err(e);
+            } else {
+                error!(
+                    "readahead failed on file id: {} with: {}",
+                    record.file_id.clone(),
+                    e.to_string()
+                );
+                continue;
+            }
+        }
+    }
+}
+
+fn worker(
+    id: usize,
+    state: Arc<Mutex<SharedState>>,
+    records_file: Arc<RwLock<RecordsFile>>,
+    exit_on_error: bool,
+    exclude_files_regex: Vec<Regex>,
+    buffer: &mut [u8],
+) {
+    let _dbg = scoped_log(id, "read_loop");
+    let result = worker_internal(
+        id,
+        state.clone(),
+        records_file,
+        exit_on_error,
+        exclude_files_regex,
+        buffer,
+    );
+    if result.is_err() {
+        error!("worker failed with {:?}", result);
+        let mut state = state.lock().unwrap();
+        if state.result.is_ok() {
+            state.result = result;
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct SharedState {
+    fds: LruCache<FileId, Arc<File>>,
+    records_index: usize,
+    result: Result<(), Error>,
+}
+
+impl SharedState {
+    fn next_record(&mut self) -> usize {
+        let ret = self.records_index;
+        self.records_index += 1;
+        ret
+    }
+}
+
+/// Runtime, in-memory, representation of records file structure.
+#[derive(Debug)]
+pub struct Replay {
+    records_file: Arc<RwLock<RecordsFile>>,
+    io_depth: u16,
+    exit_on_error: bool,
+    state: Arc<Mutex<SharedState>>,
+    exclude_files_regex: Vec<Regex>,
+}
+
+impl Replay {
+    /// Creates Replay from input `args`.
+    pub fn new(args: &ReplayArgs) -> Result<Self, Error> {
+        let _dbg = scoped_log(1, "new");
+        let reader: File = File::open(&args.path).map_err(|source| Error::Open {
+            source,
+            path: args.path.to_str().unwrap().to_owned(),
+        })?;
+        let rf: RecordsFile = serde_cbor::from_reader(reader)
+            .map_err(|error| Error::Deserialize { error: error.to_string() })?;
+
+        let mut exclude_files_regex: Vec<Regex> = Vec::new();
+        // The path to the configuration file is optional in the command.
+        // If the path is provided, the configuration file will be read.
+        if !&args.config_path.as_os_str().is_empty() {
+            let config_reader = File::open(&args.config_path).map_err(|source| Error::Open {
+                source,
+                path: args.path.to_str().unwrap().to_owned(),
+            })?;
+            let cf: ConfigFile = serde_json::from_reader(config_reader)
+                .map_err(|error| Error::Deserialize { error: error.to_string() })?;
+
+            for file_to_exclude in &cf.files_to_exclude_regex {
+                exclude_files_regex.push(Regex::new(file_to_exclude).unwrap());
+            }
+        }
+
+        Ok(Self {
+            records_file: Arc::new(RwLock::new(rf)),
+            io_depth: args.io_depth,
+            exit_on_error: args.exit_on_error,
+            state: Arc::new(Mutex::new(SharedState {
+                fds: LruCache::new(args.max_fds.into()),
+                records_index: 0,
+                result: Ok(()),
+            })),
+            exclude_files_regex,
+        })
+    }
+
+    /// Replay records.
+    pub fn replay(self) -> Result<(), Error> {
+        let _dbg = scoped_log(1, "replay");
+        let mut threads = vec![];
+        for i in 0..self.io_depth {
+            let i_clone = i as usize;
+            let state = self.state.clone();
+            let records_file = self.records_file.clone();
+            let exit_on_error = self.exit_on_error;
+            let exclude_files_regex = self.exclude_files_regex.clone();
+
+            let mut buffer = Box::new([0u8; READ_SZ]);
+
+            threads.push(thread::Builder::new().spawn(move || {
+                worker(
+                    i_clone,
+                    state,
+                    records_file,
+                    exit_on_error,
+                    exclude_files_regex,
+                    buffer.as_mut_slice(),
+                )
+            }));
+        }
+        for thread in threads {
+            thread.unwrap().join().unwrap();
+        }
+        replace(&mut self.state.lock().unwrap().result, Ok(()))
+    }
+}
+
+// WARNING: flaky tests.
+// In these tests we create files, invalidate their caches and then replay.
+// Verify that after reply the same portions of data is in memory.
+//
+// Since these tests to rely on presence or absence of data in cache, the
+// files used by the tests should not be in tmp filesystem. So we use relative
+// path as target directory. There is no guarantee that this target directory
+// is not on temp filesystem but chances are better than using target directory
+// in tempfs.
+//
+// Tests can be flaky if the system under tests is running low on memory. The
+// tests create file using O_DIRECT so that no data is left in file cache.
+// Though this is sufficient to avoid caching, but other processes reading these
+// files(like anti-virus) or some other system processes might change the state
+// of the cache. Or it may happen that the filesystem evicts the file before
+// we verify that read ahead worked as intended.
+#[cfg(test)]
+pub mod tests {
+    use std::{
+        assert,
+        io::Write,
+        ops::Range,
+        path::{Path, PathBuf},
+        time::Duration,
+    };
+
+    use crate::format::DeviceNumber;
+    use crate::format::FsInfo;
+    use crate::format::InodeNumber;
+    use crate::nanoseconds_since_boot;
+    use nix::sys::mman::MapFlags;
+    use nix::sys::mman::ProtFlags;
+    use serde::Deserialize;
+    use serde::Serialize;
+    use std::collections::HashMap;
+    use std::fs::OpenOptions;
+    use std::num::NonZeroUsize;
+    use std::os::fd::AsFd;
+    use std::os::unix::fs::symlink;
+    use std::os::unix::fs::MetadataExt;
+    use std::ptr::NonNull;
+    use tempfile::NamedTempFile;
+
+    use super::*;
+    use crate::tracer::{
+        page_size,
+        tests::{copy_uncached_files_and_record_from, setup_test_dir},
+    };
+
+    static MB: u64 = 1024 * 1024;
+    static KB: u64 = 1024;
+
+    fn random_write(file: &mut NamedTempFile, base: u64) -> Range<u64> {
+        let start: u64 = base + (rand::random::<u64>() % (base / 2)) as u64;
+        let len: u64 = rand::random::<u64>() % (32 * KB);
+        let buf = vec![5; len as usize];
+        nix::sys::uio::pwrite(file.as_fd(), &buf, start as i64).unwrap();
+        start..(start + len)
+    }
+
+    pub(crate) fn create_file(
+        path: Option<&Path>,
+        align: Option<u64>,
+    ) -> (NamedTempFile, Vec<Range<u64>>) {
+        let mut file = if let Some(path) = path {
+            NamedTempFile::new_in(path).unwrap()
+        } else {
+            NamedTempFile::new().unwrap()
+        };
+        let range1 = random_write(&mut file, 32 * KB);
+        let range2 = random_write(&mut file, 128 * KB);
+        let range3 = random_write(&mut file, 4 * MB);
+        if let Some(align) = align {
+            let orig_size = file.metadata().unwrap().len();
+            let aligned_size = orig_size + (align - (orig_size % align));
+            file.set_len(aligned_size).unwrap();
+        }
+        (file, vec![range1, range2, range3])
+    }
+
+    pub(crate) fn generate_cached_files_and_record(
+        path: Option<&Path>,
+        create_symlink: bool,
+        align: Option<u64>,
+    ) -> (RecordsFile, Vec<(NamedTempFile, Vec<Range<u64>>)>) {
+        let file1 = create_file(path, align);
+        let file2 = create_file(path, align);
+        let file3 = create_file(path, align);
+
+        let mut f: RecordsFileBuilder = Default::default();
+        f.add_file(file1.0.path().to_str().unwrap());
+        f.add_file(file2.0.path().to_str().unwrap());
+        f.add_file(file3.0.path().to_str().unwrap());
+        if create_symlink {
+            let symlink_path = format!("{}-symlink", file1.0.path().to_str().unwrap());
+            symlink(file1.0.path().file_name().unwrap(), &symlink_path).unwrap();
+
+            f.add_file(&symlink_path);
+        }
+        let rf = f.build().unwrap();
+        (rf, vec![file1, file2, file3])
+    }
+
+    /// RecordsFileBuilder is primarily used for testing purpose. This
+    /// is a thin wrapper around "Record". This gives the ability
+    /// to test Records functionality. The flow of this test is as follows:
+    ///
+    /// 1: generate_cached_files_and_record -> This will create temporary files of different length
+    /// and builds the "RecordFile" format.
+    /// 2: For each of the file path create, a "RecordsFile" is generated.
+    ///    a: mmap the file based on the length.
+    ///    b: call mincore() to get the residency of pages in memory for the given
+    ///    length.
+    ///    c: Iterate over the buffer of pages returned by mincore(). If a page
+    ///    is not resident in RAM, construct the "Record" structure.
+    /// 3: build() function will finally return a constructed Prefetch Record which
+    /// contains all the "Record" structure required for "Replay".
+    #[derive(Debug, Default, Deserialize, Serialize)]
+    pub struct RecordsFileBuilder {
+        // Temporarily holds paths of all files opened by other processes.
+        pub(crate) paths: HashMap<String, FileId>,
+
+        // Read inode numbers
+        inode_numbers: HashMap<(DeviceNumber, InodeNumber), FileId>,
+    }
+
+    impl RecordsFileBuilder {
+        pub fn add_file(&mut self, path: &str) {
+            if self.paths.contains_key(path) {
+                return;
+            }
+
+            self.paths.insert(path.to_owned(), FileId(self.paths.len() as u64));
+        }
+
+        pub fn build(&mut self) -> Result<RecordsFile, Error> {
+            let mut rf = RecordsFile::default();
+            for (path, mut id) in self.paths.drain() {
+                let stat = Path::new(&path)
+                    .metadata()
+                    .map_err(|source| Error::Stat { source, path: path.clone() })?;
+
+                rf.inner
+                    .filesystems
+                    .entry(stat.dev())
+                    .or_insert(FsInfo { block_size: stat.blksize() });
+
+                if let Some(orig_id) = self.inode_numbers.get(&(stat.dev(), stat.ino())) {
+                    let inode = rf.inner.inode_map.get_mut(orig_id).unwrap();
+                    inode.paths.push(path.clone());
+
+                    // There may be multiple paths for the file so from those path we may have multiple
+                    // ids. Override the id.
+                    id = orig_id.clone();
+                } else {
+                    self.inode_numbers.insert((stat.dev(), stat.ino()), id.clone());
+                    rf.insert_or_update_inode(id.clone(), &stat, path.clone());
+                }
+                if let Some(mmap) = Mmap::create(&path, id)? {
+                    mmap.get_records(&mut rf.inner.records)?;
+                }
+            }
+            Ok(rf)
+        }
+    }
+
+    #[derive(Debug)]
+    pub(crate) struct Mmap {
+        map_addr: *mut c_void,
+        length: usize,
+        #[allow(dead_code)]
+        file: File,
+        file_id: FileId,
+    }
+
+    impl Mmap {
+        pub fn create(path: &str, file_id: FileId) -> Result<Option<Self>, Error> {
+            let file = OpenOptions::new()
+                .read(true)
+                .write(false)
+                .open(path)
+                .map_err(|source| Error::Open { source, path: path.to_owned() })?;
+
+            let length = file
+                .metadata()
+                .map_err(|source| Error::Stat { source, path: path.to_owned() })?
+                .len() as usize;
+
+            if length == 0 {
+                return Ok(None);
+            }
+
+            // SAFETY: This is safe because
+            // - the length is checked for zero
+            // - offset is set to 0
+            let map_addr = unsafe {
+                nix::sys::mman::mmap(
+                    None,
+                    NonZeroUsize::new(length).unwrap(),
+                    ProtFlags::PROT_READ,
+                    MapFlags::MAP_SHARED,
+                    file.as_fd(),
+                    0,
+                )
+                .map_err(|source| Error::Mmap {
+                    error: source.to_string(),
+                    path: path.to_owned(),
+                })?
+            };
+
+            Ok(Some(Self { map_addr: map_addr.as_ptr(), length, file, file_id }))
+        }
+
+        /// Construct the "Record" file based on pages resident in RAM.
+        pub(crate) fn get_records(&self, records: &mut Vec<Record>) -> Result<(), Error> {
+            let page_size = page_size()?;
+            let page_count = (self.length + page_size - 1) / page_size;
+            let mut buf: Vec<u8> = vec![0_u8; page_count];
+            // SAFETY: This is safe because
+            // - the file is mapped
+            // - buf points to a valid and sufficiently large memory region with the
+            //   requirement of (length+PAGE_SIZE-1) / PAGE_SIZE bytes
+            let ret = unsafe { libc::mincore(self.map_addr, self.length, buf.as_mut_ptr()) };
+            if ret < 0 {
+                return Err(Error::Custom {
+                    error: format!("failed to query resident pages: {}", Errno::last_raw()),
+                });
+            }
+            let mut i = 0;
+
+            let mut offset_length: Option<(u64, u64)> = None;
+            for (index, resident) in buf.iter().enumerate() {
+                if *resident != 0 {
+                    if let Some((_, length)) = &mut offset_length {
+                        *length += page_size as u64;
+                    } else {
+                        offset_length = Some((index as u64 * page_size as u64, page_size as u64));
+                    }
+                } else if let Some((offset, length)) = offset_length {
+                    i += 1;
+                    records.push(Record {
+                        file_id: self.file_id.clone(),
+                        offset,
+                        length,
+                        timestamp: nanoseconds_since_boot(),
+                    });
+
+                    offset_length = None;
+                }
+            }
+
+            if let Some((offset, length)) = offset_length {
+                i += 1;
+                records.push(Record {
+                    file_id: self.file_id.clone(),
+                    offset,
+                    length,
+                    timestamp: nanoseconds_since_boot(),
+                });
+            }
+            debug!("records found: {} for {:?}", i, self);
+
+            Ok(())
+        }
+    }
+
+    impl Drop for Mmap {
+        fn drop(&mut self) {
+            // SAFETY: This is safe because
+            // - addr is mapped and is multiple of page_size
+            let ret = unsafe {
+                nix::sys::mman::munmap(NonNull::new(self.map_addr).unwrap(), self.length)
+            };
+            if let Err(e) = ret {
+                error!(
+                    "failed to munmap {:p} {} with {}",
+                    self.map_addr,
+                    self.length,
+                    e.to_string()
+                );
+            }
+        }
+    }
+
+    // Please see comment above RecordsFileBuilder.
+    fn rebuild_records_file(files: &[(PathBuf, Vec<Range<u64>>)]) -> RecordsFile {
+        // Validate that caches are dropped
+        let mut f: RecordsFileBuilder = Default::default();
+        for (path, _) in files {
+            f.add_file(path.to_str().unwrap());
+        }
+        f.build().unwrap()
+    }
+
+    fn ensure_files_not_cached(files: &mut [(PathBuf, Vec<Range<u64>>)]) {
+        assert!(rebuild_records_file(files).inner.records.is_empty());
+    }
+
+    fn has_record(records: &[Record], key: &Record) -> bool {
+        for r in records {
+            if r.offset == key.offset && r.length == key.length {
+                return true;
+            }
+        }
+        false
+    }
+
+    fn compare_records(old: &[Record], new: &[Record]) {
+        for key in new {
+            if !has_record(old, key) {
+                panic!("Failed to file {:?} in {:?}", key, old);
+            }
+        }
+    }
+
+    fn create_test_config_file(files_to_exclude_regex: Vec<String>) -> String {
+        let cfg = ConfigFile { files_to_exclude_regex, ..Default::default() };
+        serde_json::to_string(&cfg).unwrap()
+    }
+
+    // TODO: Split this into individual tests for better readability.
+    // b/378554334
+    fn test_replay_internal(
+        create_symlink: bool,
+        exit_on_error: bool,
+        inject_error: bool,
+        exclude_all_files: bool,
+        empty_exclude_file_list: bool,
+    ) {
+        let page_size = page_size().unwrap() as u64;
+        let test_base_dir = setup_test_dir();
+        let (rf, mut files) =
+            generate_cached_files_and_record(None, create_symlink, Some(page_size));
+
+        // Here "uncached_files" emulate the files after reboot when none of those files data is in cache.
+        let (mut uncached_rf, mut uncached_files) =
+            copy_uncached_files_and_record_from(Path::new(&test_base_dir), &mut files, &rf);
+
+        // Injects error(s) in the form of invalid filename
+        if inject_error {
+            if let Some(v) = uncached_rf.inner.inode_map.values_mut().next() {
+                for path in &mut v.paths {
+                    path.push('-');
+                }
+            }
+        }
+
+        let mut file = NamedTempFile::new().unwrap();
+        file.write_all(&uncached_rf.add_checksum_and_serialize().unwrap()).unwrap();
+        let mut config_file = NamedTempFile::new().unwrap();
+
+        let mut files_to_exclude: Vec<String> = Vec::new();
+        if exclude_all_files {
+            // Exclude files from replay by adding them in config
+            for v in uncached_rf.inner.inode_map.values_mut() {
+                for path in &mut v.paths {
+                    files_to_exclude.push(path.to_string())
+                }
+            }
+        } else if empty_exclude_file_list {
+            files_to_exclude.extend(vec![]);
+        } else {
+            // Exclude file1 and file2 during replay
+            files_to_exclude.extend(vec!["file1".to_owned(), "file2".to_owned()]);
+        }
+
+        // Create a config json to exclude files during replay
+        let config_file_contents = create_test_config_file(files_to_exclude);
+        config_file.write_all(config_file_contents.as_bytes()).unwrap();
+
+        ensure_files_not_cached(&mut uncached_files);
+
+        let replay = Replay::new(&ReplayArgs {
+            path: file.path().to_owned(),
+            io_depth: 32,
+            max_fds: 128,
+            exit_on_error,
+            config_path: config_file.path().to_owned(),
+        })
+        .unwrap();
+
+        let result = replay.replay();
+        // Sleep a bit so that readaheads are complete.
+        thread::sleep(Duration::from_secs(1));
+
+        if exit_on_error && inject_error {
+            result.expect_err("Failure was expected");
+        } else if exclude_all_files {
+            let new_rf = rebuild_records_file(&uncached_files);
+            assert!(new_rf.inner.records.is_empty());
+        } else {
+            result.unwrap();
+
+            // At this point, we have prefetched data for uncached file bringing same set of
+            // data in memory as the original cached files.
+            // If we record prefetch data for new files, we should get same records files
+            // (offset and lengths) except that the file names should be different.
+            // This block verifies it.
+            // Note: `new_rf` is for uncached_files. But, [un]fortunately, those "uncached_files"
+            // are now cached after we replayed the records.
+            let new_rf = rebuild_records_file(&uncached_files);
+            assert!(!new_rf.inner.records.is_empty());
+            assert_eq!(rf.inner.inode_map.len(), new_rf.inner.inode_map.len());
+            assert_eq!(rf.inner.records.len(), new_rf.inner.records.len());
+            compare_records(&rf.inner.records, &new_rf.inner.records);
+        }
+    }
+
+    #[test]
+    fn test_replay() {
+        test_replay_internal(true, false, false, false, false);
+    }
+
+    #[test]
+    fn test_replay_strict() {
+        test_replay_internal(true, true, false, false, false);
+    }
+
+    #[test]
+    fn test_replay_no_symlink() {
+        test_replay_internal(false, false, false, false, false);
+    }
+
+    #[test]
+    fn test_replay_no_symlink_strict() {
+        test_replay_internal(false, true, false, false, false);
+    }
+
+    #[test]
+    fn test_replay_fails_on_error() {
+        test_replay_internal(true, true, true, false, false);
+    }
+
+    #[test]
+    fn test_replay_exclude_all_files() {
+        test_replay_internal(true, false, false, true, false);
+    }
+
+    #[test]
+    fn test_replay_empty_exclude_files_list() {
+        test_replay_internal(true, false, false, false, true);
+    }
+}
diff --git a/init/libprefetch/prefetch/src/tracer/mem.rs b/init/libprefetch/prefetch/src/tracer/mem.rs
new file mode 100644
index 0000000..f69ae80
--- /dev/null
+++ b/init/libprefetch/prefetch/src/tracer/mem.rs
@@ -0,0 +1,897 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! See top level documentation for `crate::tracer`.
+
+use std::collections::hash_map::Iter;
+use std::fs::symlink_metadata;
+use std::io::{ErrorKind, Write};
+use std::iter::Iterator;
+use std::mem::take;
+use std::os::unix::fs::MetadataExt;
+use std::{
+    collections::{HashMap, HashSet},
+    fs::read_to_string,
+    option::Option,
+    path::{Path, PathBuf},
+};
+
+use log::{debug, error, info, warn};
+use regex::Regex;
+use serde::Deserialize;
+use serde::Serialize;
+use walkdir::{DirEntry, WalkDir};
+
+use crate::format::{coalesce_records, FsInfo};
+use crate::tracer::{page_size, TracerConfigs};
+use crate::{
+    format::{DeviceNumber, InodeNumber},
+    tracer::{TraceSubsystem, EXCLUDE_PATHS},
+    Error, FileId, Record, RecordsFile,
+};
+
+static MOUNTINFO_PATH: &str = "/proc/self/mountinfo";
+
+// Trace events to enable
+// Paths are relative to trace mount point
+static TRACE_EVENTS: &[&str] =
+    &["events/filemap/mm_filemap_add_to_page_cache/enable", "tracing_on"];
+
+// Filesystem types to ignore
+static EXCLUDED_FILESYSTEM_TYPES: &[&str] = &[
+    "binder",
+    "bpf",
+    "cgroup",
+    "cgroup2",
+    "configfs",
+    "devpts",
+    "fuse", // No emulated storage
+    "fusectl",
+    "proc",
+    "pstore",
+    "selinuxfs",
+    "sysfs",
+    "tmpfs", // Check for apex mount points
+    "tracefs",
+    "functionfs", // adb, fastboot
+    "f2fs",       // Skip /data mounts
+];
+
+#[cfg(target_os = "linux")]
+type MajorMinorType = u32;
+#[cfg(target_os = "android")]
+type MajorMinorType = i32;
+
+// TODO(b/302056482): Once we uprev nix crate, we can use the function exported by the crate.
+fn major(dev: DeviceNumber) -> MajorMinorType {
+    (((dev >> 32) & 0xffff_f000) | ((dev >> 8) & 0x0000_0fff)) as MajorMinorType
+}
+
+// TODO(b/302056482): Once we uprev nix crate, we can use the function exported by the crate.
+fn minor(dev: DeviceNumber) -> MajorMinorType {
+    (((dev >> 12) & 0xffff_ff00) | ((dev) & 0x0000_00ff)) as MajorMinorType
+}
+
+// TODO(b/302056482): Once we uprev nix crate, we can use the function exported by the crate.
+fn makedev(major: MajorMinorType, minor: MajorMinorType) -> DeviceNumber {
+    let major = major as DeviceNumber;
+    let minor = minor as DeviceNumber;
+    ((major & 0xffff_f000) << 32)
+        | ((major & 0x0000_0fff) << 8)
+        | ((minor & 0xffff_ff00) << 12)
+        | (minor & 0x0000_00ff)
+}
+
+fn build_device_number(major: &str, minor: &str) -> Result<DeviceNumber, Error> {
+    Ok(makedev(
+        major.parse::<MajorMinorType>().map_err(|e| Error::Custom {
+            error: format!("Failed to parse major number from {} with {}", major, e),
+        })?,
+        minor.parse::<MajorMinorType>().map_err(|e| Error::Custom {
+            error: format!("Failed to parse major number from {} with {}", major, e),
+        })?,
+    ))
+}
+
+// Returns timestamp in nanoseconds
+fn build_timestamp(seconds: &str, microseconds: &str) -> Result<u64, Error> {
+    let seconds = seconds.parse::<u64>().map_err(|e| Error::Custom {
+        error: format!("Failed to parse seconds from {} with {}", seconds, e),
+    })?;
+    let microseconds = microseconds.parse::<u64>().map_err(|e| Error::Custom {
+        error: format!("Failed to parse microseconds from {} with {}", seconds, e),
+    })?;
+    Ok((seconds * 1_000_000_000) + (microseconds * 1_000))
+}
+
+#[cfg(not(target_os = "android"))]
+fn is_highly_privileged_path(_path: &Path) -> bool {
+    false
+}
+
+#[cfg(target_os = "android")]
+fn is_highly_privileged_path(path: &Path) -> bool {
+    // Following directories contain a mix of files with and without access to stat/read.
+    // We do not completely exclude these directories as there is still a lot of
+    // file we can issue readahead on. Some of the files on which readahead fails include
+    // - /system/bin/run-as
+    // - /data/data/com.android.storagemanager
+    // - /system/apex/com.android.art/bin/dex2oat32
+    // - /data/user/0/com.android.systemui
+    //
+    // - TODO: /system/apex: Apex files in read-only partition may be read during boot.
+    // However, some files may not have access. Double check the record files
+    // to filter out the exact path.
+    let privileged_paths = [
+        "/data/data",
+        "/data/user/0",
+        "/data/user_de/0",
+        "/system/bin/",
+        "/system/etc/selinux/",
+        "/system/system_ext/etc/selinux/",
+        "/system/product/etc/selinux/",
+        "/system/vendor/etc/selinux/",
+        "/system_ext/etc/selinux/",
+        "/product/etc/selinux/",
+        "/vendor/etc/selinux/",
+        "/system/xbin",
+        "/system/etc/",
+        "/data/",
+        "/postinstall/",
+        "/mnt/",
+        "/metadata/",
+    ];
+    for privileged in privileged_paths {
+        if path.to_str().unwrap().starts_with(privileged) {
+            return true;
+        }
+    }
+    false
+}
+
+enum DeviceState {
+    Include((DeviceNumber, PathBuf)),
+    Exclude(DeviceNumber),
+}
+
+/// Utility struct that helps to include and exclude devices and mount points that need and don't
+/// need prefetching.
+#[derive(Debug, Deserialize, Serialize)]
+struct MountInfo {
+    // Map of device number to mount points
+    included_devices: HashMap<DeviceNumber, PathBuf>,
+
+    // Devices that we don't want to prefetch - like devices backing tempfs and sysfs
+    excluded_devices: HashSet<DeviceNumber>,
+}
+
+impl MountInfo {
+    // Parses file at `path` to build `Self`.`
+    fn create(path: &str) -> Result<Self, Error> {
+        let buf = read_to_string(path)
+            .map_err(|e| Error::Read { error: format!("Reading {} failed with: {}", path, e) })?;
+        Self::with_buf(&buf)
+    }
+
+    // Parses string in `buf` to build `Self`.
+    fn with_buf(buf: &str) -> Result<Self, Error> {
+        let regex = Self::get_regex()?;
+        let mut included_devices: HashMap<DeviceNumber, PathBuf> = HashMap::new();
+        let mut excluded_devices = HashSet::new();
+        let excluded_filesystem_types: HashSet<String> =
+            EXCLUDED_FILESYSTEM_TYPES.iter().map(|s| String::from(*s)).collect();
+        for line in buf.lines() {
+            if let Some(state) = Self::parse_line(&regex, &excluded_filesystem_types, line)? {
+                match state {
+                    DeviceState::Include((device, path)) => {
+                        included_devices.insert(device, path);
+                    }
+                    DeviceState::Exclude(device) => {
+                        excluded_devices.insert(device);
+                    }
+                }
+            }
+        }
+
+        Ok(Self { included_devices, excluded_devices })
+    }
+
+    fn parse_line(
+        re: &Regex,
+        excluded_filesystem_types: &HashSet<String>,
+        line: &str,
+    ) -> Result<Option<DeviceState>, Error> {
+        let caps = match re.captures(line) {
+            Some(caps) => caps,
+            None => {
+                return Ok(None);
+            }
+        };
+        if &caps["relative_path"] != "/" {
+            return Ok(None);
+        }
+
+        let mount_point = &caps["mount_point"];
+        let mnt_pnt_with_slash = format!("{}/", mount_point);
+        let device_number = build_device_number(&caps["major"], &caps["minor"])?;
+        let fs_type = &caps["fs_type"];
+
+        if excluded_filesystem_types.contains(fs_type) {
+            info!(
+                "excluding fs type: {} for {} mount-point {} slash {}",
+                fs_type, line, mount_point, mnt_pnt_with_slash
+            );
+            return Ok(Some(DeviceState::Exclude(device_number)));
+        }
+
+        for excluded in EXCLUDE_PATHS {
+            if mnt_pnt_with_slash.starts_with(excluded) {
+                info!(
+                    "exclude-paths fs type: {} for {} mount-point {} slash {}",
+                    fs_type, line, mount_point, mnt_pnt_with_slash
+                );
+                return Ok(Some(DeviceState::Exclude(device_number)));
+            }
+        }
+
+        Ok(Some(DeviceState::Include((device_number, PathBuf::from(mount_point)))))
+    }
+
+    fn get_regex() -> Result<Regex, Error> {
+        Regex::new(concat!(
+            r"^\s*(?P<id_unknown1>\S+)",
+            r"\s+(?P<id_unknown2>\S+)",
+            r"\s+(?P<major>[0-9]+):(?P<minor>[0-9]+)",
+            r"\s+(?P<relative_path>\S+)",
+            r"\s+(?P<mount_point>\S+)",
+            r"\s+(?P<mount_opt>\S+)",
+            r"\s+(?P<shared>\S+)",
+            r"\s+\S+",
+            r"\s+(?P<fs_type>\S+)",
+            r"\s+(?P<device_path>\S+)"
+        ))
+        .map_err(|e| Error::Custom {
+            error: format!("create regex for parsing mountinfo failed with: {}", e),
+        })
+    }
+
+    fn is_excluded(&self, device: &DeviceNumber) -> bool {
+        self.excluded_devices.contains(device)
+    }
+
+    fn get_included(&self) -> Iter<DeviceNumber, PathBuf> {
+        self.included_devices.iter()
+    }
+}
+
+#[derive(Default, PartialEq, Debug, Eq, Hash)]
+struct TraceLineInfo {
+    device: DeviceNumber,
+    inode: InodeNumber,
+    offset: u64,
+    timestamp: u64,
+}
+
+impl TraceLineInfo {
+    pub fn from_trace_line(re: &Regex, line: &str) -> Result<Option<Self>, Error> {
+        let caps = match re.captures(line) {
+            Some(caps) => caps,
+            None => return Ok(None),
+        };
+        let major = &caps["major"];
+        let minor = &caps["minor"];
+        let ino = &caps["ino"];
+        let offset = &caps["offset"];
+        let timestamp = build_timestamp(&caps["seconds"], &caps["microseconds"])?;
+        Ok(Some(TraceLineInfo {
+            device: build_device_number(major, minor)?,
+            inode: u64::from_str_radix(ino, 16).map_err(|e| Error::Custom {
+                error: format!("failed parsing inode: {} : {}", ino, e),
+            })?,
+            offset: offset.parse::<u64>().map_err(|e| Error::Custom {
+                error: format!("failed parsing offset: {} : {}", offset, e),
+            })?,
+            timestamp,
+        }))
+    }
+
+    #[cfg(test)]
+    pub fn from_fields(
+        major: MajorMinorType,
+        minor: MajorMinorType,
+        inode: u64,
+        offset: u64,
+        timestamp: u64,
+    ) -> Self {
+        Self { device: makedev(major, minor), inode, offset, timestamp }
+    }
+
+    // Convenience function to create regex. Used once per life of `record` but multiple times in
+    // case of tests.
+    pub fn get_trace_line_regex() -> Result<Regex, Error> {
+        // TODO: Fix this Regex expression for 5.15 kernels. This expression
+        // works only on 6.1+. Prior to 6.1, "<page>" was present in the output.
+        Regex::new(concat!(
+            r"^\s+(?P<cmd_pid>\S+)",
+            r"\s+(?P<cpu>\S+)",
+            r"\s+(?P<irq_stuff>\S+)",
+            r"\s+(?P<seconds>[0-9]+)\.(?P<microseconds>[0-9]+):",
+            r"\s+mm_filemap_add_to_page_cache:",
+            r"\s+dev\s+(?P<major>[0-9]+):(?P<minor>[0-9]+)",
+            r"\s+ino\s+(?P<ino>\S+)",
+            //r"\s+(?P<page>\S+)",
+            r"\s+(?P<pfn>\S+)",
+            r"\s+ofs=(?P<offset>[0-9]+)"
+        ))
+        .map_err(|e| Error::Custom {
+            error: format!("create regex for tracing failed with: {}", e),
+        })
+    }
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct MissingFile {
+    major_no: MajorMinorType,
+    minor_no: MajorMinorType,
+    inode: InodeNumber,
+    records: Vec<Record>,
+}
+
+#[derive(Debug, Default, Deserialize, Serialize)]
+struct DebugInfo {
+    // Check all inodes for which paths don't exists. These are the files which
+    // * got deleted before we got to them
+    // * are filesystem internal files that fs access only via inode numbers.
+    missing_files: HashMap<FileId, MissingFile>,
+
+    // Number of bytes read that belongs to directory type inodes.
+    directory_read_bytes: u64,
+
+    // Number of bytes read from files for which we could not find a path in
+    // the filesystems.
+    missing_path_bytes: u64,
+
+    // Paths for which the current process doesn't have read permission.
+    privileged_paths: Vec<PathBuf>,
+}
+
+#[derive(Debug, Serialize)]
+pub(crate) struct MemTraceSubsystem {
+    device_inode_map: HashMap<DeviceNumber, HashMap<InodeNumber, FileId>>,
+    // Count of all InodeNumber held by `device_inode_map`. This is handy to assign unique
+    // FileId.
+    inode_count: u64,
+
+    // `Record`s built from parsing read trace lines.
+    records: Vec<Record>,
+
+    // Regex to parse lines from trace_pipe.
+    #[serde(skip_serializing)]
+    regex: Regex,
+
+    // Mounted devices/filesystems either at the time of parsing trace file or at the time
+    // of building RecordsFile from parsed lines.
+    mount_info: MountInfo,
+
+    // A copy of TracerConfigs
+    tracer_configs: Option<TracerConfigs>,
+
+    // system page size stored to avoid frequent syscall to get the page size.
+    page_size: u64,
+
+    // The fields of the debug_info are populated when build_records_file is called (after lines
+    // are parsed from the trace file/pipe).
+    debug_info: DebugInfo,
+}
+
+impl MemTraceSubsystem {
+    pub fn update_configs(configs: &mut TracerConfigs) {
+        for path in EXCLUDE_PATHS {
+            configs.excluded_paths.push(path.to_owned().to_string());
+        }
+
+        for event in TRACE_EVENTS {
+            configs.trace_events.push(event.to_owned().to_string());
+        }
+        configs.mountinfo_path = Some(MOUNTINFO_PATH.to_string());
+    }
+
+    pub fn create_with_configs(tracer_configs: TracerConfigs) -> Result<Self, Error> {
+        static INITIAL_RECORDS_CAPACITY: usize = 100_000;
+        debug!("TracerConfig: {:#?}", tracer_configs);
+
+        let regex = TraceLineInfo::get_trace_line_regex()?;
+        let mount_info = MountInfo::create(tracer_configs.mountinfo_path.as_ref().unwrap())?;
+        debug!("mountinfo: {:#?}", mount_info);
+
+        Ok(Self {
+            device_inode_map: HashMap::new(),
+            inode_count: 0,
+            // For one product of android, we see around 50k records. To avoid a lot allocations
+            // and copying of records, we create a vec of this size.
+            //
+            // We do this to reduces chances of losing data, however unlikely, coming over
+            // `trace_pipe`.
+            //
+            // Note: Once we are done reading trace lines, we are less pedantic about allocations
+            // and mem copies.
+            records: Vec::with_capacity(INITIAL_RECORDS_CAPACITY),
+            regex,
+            mount_info,
+            tracer_configs: Some(tracer_configs),
+            page_size: page_size()? as u64,
+            debug_info: DebugInfo {
+                missing_files: HashMap::new(),
+                directory_read_bytes: 0,
+                missing_path_bytes: 0,
+                privileged_paths: vec![],
+            },
+        })
+    }
+
+    fn new_file_id(&mut self) -> FileId {
+        let id = self.inode_count;
+        self.inode_count += 1;
+        FileId(id)
+    }
+
+    fn get_trace_info(&self, line: &str) -> Result<Option<TraceLineInfo>, Error> {
+        TraceLineInfo::from_trace_line(&self.regex, line)
+    }
+
+    // Returns true if the file or directory is on a device which is excluded from walking.
+    // If the path was excluded because the current process doesn't have privileged to read it,
+    // the path gets added to `privileged` list.
+    fn is_excluded(&self, entry: &DirEntry, device: u64, privileged: &mut Vec<PathBuf>) -> bool {
+        // We skip paths that are reside on excluded devices here. This is ok because a
+        // non-excluded mount point will have a separate entry in MountInfo. For example
+        // - `/` has ext4
+        // - `/tmp` has tempfs
+        // - `/tmp/mnt` has ext4 that we are interested in.
+        // MountInfo will have three entries - `/`, `/tmp/` and `/tmp/mnt`. Skipping walking
+        // `/tmp` while walking `/` is ok as next `mount_info.get_included()` will return
+        // `/tmp/mnt` path.
+        //
+        //
+        // We skip links here as they can refer to mount points across
+        // filesystems. If that path is valid and access are valid, then
+        // we should have entry by the file's <device, inode> pair.
+        //
+        //
+        // We skip devices that don't match current walking device because we eventually
+        // walk other devices.
+        match symlink_metadata(entry.path()) {
+            Ok(lstat) => {
+                if self.mount_info.is_excluded(&lstat.dev())
+                    || lstat.dev() != device
+                    || lstat.file_type().is_symlink()
+                {
+                    return true;
+                }
+            }
+            Err(e) => {
+                error!("stat on {} failed with {}", entry.path().to_str().unwrap(), e);
+
+                // We treat EACCES special because on some platforms, like android, process needs to
+                // have very special set of permissions to access some inodes.
+                // We ignore errors in such cases *after* making an effort to get to them.
+                if e.kind() == ErrorKind::PermissionDenied
+                    && is_highly_privileged_path(entry.path())
+                {
+                    privileged.push(entry.path().to_owned());
+                    return true;
+                }
+            }
+        }
+
+        // On error, we return false because if lstat has failed, it will fail following operations
+        // including stat.
+        false
+    }
+}
+
+impl TraceSubsystem for MemTraceSubsystem {
+    fn add_line(&mut self, line: &str) -> Result<(), Error> {
+        if let Some(info) = self.get_trace_info(line)? {
+            if self.mount_info.is_excluded(&info.device) {
+                return Ok(());
+            }
+
+            self.device_inode_map.entry(info.device).or_default();
+
+            let file_id = if let Some(id) =
+                self.device_inode_map.get_mut(&info.device).unwrap().get(&info.inode)
+            {
+                id.clone()
+            } else {
+                self.new_file_id()
+            };
+            self.device_inode_map
+                .get_mut(&info.device)
+                .unwrap()
+                .insert(info.inode, file_id.clone());
+
+            self.records.push(Record {
+                file_id,
+                offset: info.offset,
+                length: self.page_size,
+                timestamp: info.timestamp,
+            });
+        }
+
+        Ok(())
+    }
+
+    fn build_records_file(&mut self) -> Result<RecordsFile, Error> {
+        // reset debug_info in case build_records_file was called twice.
+        self.debug_info = DebugInfo::default();
+        let mut rf = RecordsFile::default();
+        let mut directories = HashSet::new();
+
+        // TODO(b/302194377): We are holding all privileged_paths in this variable and then
+        // transferring it to `self.debug_info.privileged_paths` later. We can avoid this step
+        // if we directly update `self.debug_info.privileged_paths`. To do so, we need to refactor
+        // code to make borrow not complain at several places - ex. immutably borrowing
+        // `self.mount_info` in outer loop and then mutably borrowing
+        // `self.debug_info.privileged_paths`.
+        let mut privileged_paths = vec![];
+
+        // Reload mount_info. When we created mount_info for the first time, maybe
+        // the system was in early boot phase. Reload the mount_info so as to get
+        // current/new mount points.
+        if let Some(tracer_config) = &self.tracer_configs {
+            self.mount_info = MountInfo::create(tracer_config.mountinfo_path.as_ref().unwrap())?;
+            debug!("reloaded mountinfo: {:#?}", self.mount_info);
+        }
+
+        for (device, root_path) in self.mount_info.get_included() {
+            let inode_map = if let Some(map) = self.device_inode_map.get(device) {
+                map
+            } else {
+                continue;
+            };
+
+            if inode_map.is_empty() {
+                return Err(Error::Custom {
+                    error: format!("Unexpected empty records for {:?}", root_path),
+                });
+            }
+
+            let mut block_size = 0;
+            let walker = WalkDir::new(root_path).into_iter();
+
+            for entry in
+                walker.filter_entry(|e| !self.is_excluded(e, *device, &mut privileged_paths))
+            {
+                let path = match entry {
+                    Ok(entry) => entry.path().to_owned(),
+                    Err(e) => {
+                        error!("walking directory failed: {} {}", root_path.to_str().unwrap(), e);
+                        continue;
+                    }
+                };
+
+                let stat = match path.metadata() {
+                    Ok(stat) => stat,
+                    Err(e) => {
+                        error!("stat on {} failed with {}", path.to_str().unwrap(), e);
+                        continue;
+                    }
+                };
+
+                block_size = stat.blksize();
+
+                let file_id = if let Some(id) = inode_map.get(&stat.ino()) {
+                    id.clone()
+                } else {
+                    continue;
+                };
+
+                // We cannot issue a normal readahead on directories. So we skip those records that
+                // belong to directories.
+                if stat.file_type().is_dir() {
+                    info!(
+                        "skipping directory readahead record for file_id:{file_id} ino:{} path:{} ",
+                        stat.ino(),
+                        path.to_str().unwrap()
+                    );
+                    directories.insert(file_id.clone());
+                    continue;
+                }
+
+                rf.insert_or_update_inode(file_id, &stat, path.to_str().unwrap().to_owned());
+            }
+
+            rf.inner.filesystems.insert(*device, FsInfo { block_size });
+        }
+
+        self.debug_info.privileged_paths.append(&mut privileged_paths);
+
+        for (device, inode_map) in &self.device_inode_map {
+            for (inode, file_id) in inode_map {
+                if !rf.inner.inode_map.contains_key(file_id) {
+                    let major_no: MajorMinorType = major(*device);
+                    let minor_no: MajorMinorType = minor(*device);
+                    self.debug_info.missing_files.insert(
+                        file_id.clone(),
+                        MissingFile { major_no, minor_no, inode: *inode, records: vec![] },
+                    );
+                }
+            }
+        }
+
+        // Remove all records that belong to directories or for which we did not find paths.
+        let mut records = vec![];
+        for record in take(&mut self.records) {
+            if directories.contains(&record.file_id) {
+                self.debug_info.directory_read_bytes += record.length;
+            } else if let Some(missing_file) =
+                self.debug_info.missing_files.get_mut(&record.file_id)
+            {
+                self.debug_info.missing_path_bytes += record.length;
+                missing_file.records.push(record);
+            } else {
+                records.push(record);
+            }
+        }
+
+        warn!(
+            "Recorded {} bytes worth of data read from directories",
+            self.debug_info.directory_read_bytes
+        );
+        warn!(
+            "Recorded {} bytes worth of data read from files that don't have paths",
+            self.debug_info.missing_path_bytes
+        );
+
+        rf.inner.records = coalesce_records(records, true);
+
+        Ok(rf)
+    }
+
+    fn serialize(&self, write: &mut dyn Write) -> Result<(), Error> {
+        write
+            .write_all(
+                &serde_json::to_vec(&self)
+                    .map_err(|e| Error::Serialize { error: e.to_string() })?,
+            )
+            .map_err(|source| Error::Write { path: "intermediate file".to_owned(), source })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use nix::sys::stat::{major, minor};
+    use std::assert_eq;
+    use std::path::Path;
+
+    use crate::tracer::tests::{copy_uncached_files_and_record_from, setup_test_dir};
+
+    use crate::replay::tests::generate_cached_files_and_record;
+
+    use super::*;
+
+    static TRACE_BUFFER: &str = r#"
+ Settingide-502  [001] ....   484.360292: mm_filemap_add_to_page_CACHE: dev 254:6 ino cf1 page=68d477 pfn=59833 ofs=32768
+ Settingide-502  [001] ....   484.360311: mm_filemap_add_to_page_cache: dev 254:6 ino cf1 page=759458 pfn=59827 ofs=57344
+ BOX_ENTDED-3071 [001] ....   485.276715: mm_filemap_add_to_pag_ecache: dev 254:6 ino 1 page=00cc1c pfn=81748 ofs=13574144
+ BOX_ENTDED-3071 [001] ....   485.276990: mm_filemap_add_to_page_cache: dev 254:6 ino cf2 page=36540b pfn=60952 ofs=0
+ .gms.peent-843  [001] ....   485.545516: mm_filemap_add_to_page_cache: dev 254:6 ino 1 page=002e8b pfn=58928 ofs=13578240
+ .gms.peent-843  [001] ....   485.545820: mm_filemap_add_to_page_cache: dev 254:6 ino cf3 page=6233ce pfn=58108 ofs=0
+      an.bg-459  [001] ....   494.029396: mm_filemap_add_to_page_cache: dev 254:3 ino 7cf page=c5b5c7 pfn=373933 ofs=1310720
+      an.bg-459  [001] ....   494.029398: mm_filemap_add_to_page_cache: dev 254:3 ino 7cf page=b8b9ec pfn=410074 ofs=1314816
+       "#;
+
+    fn sample_mem_traces() -> (String, Vec<Option<TraceLineInfo>>) {
+        (
+            TRACE_BUFFER.to_owned(),
+            vec![
+                None,
+                None,
+                Some(TraceLineInfo::from_fields(254, 6, 0xcf1, 57344, 484360311000)),
+                None,
+                Some(TraceLineInfo::from_fields(254, 6, 0xcf2, 0, 485276990000)),
+                Some(TraceLineInfo::from_fields(254, 6, 0x1, 13578240, 485545516000)),
+                Some(TraceLineInfo::from_fields(254, 6, 0xcf3, 0, 485545820000)),
+                Some(TraceLineInfo::from_fields(254, 3, 0x7cf, 1310720, 494029396000)),
+                Some(TraceLineInfo::from_fields(254, 3, 0x7cf, 1314816, 494029398000)),
+                None,
+            ],
+        )
+    }
+
+    #[test]
+    fn test_parse_trace_line() {
+        let (buf, res) = sample_mem_traces();
+        let re = TraceLineInfo::get_trace_line_regex().unwrap();
+        for (index, line) in buf.lines().enumerate() {
+            let found = TraceLineInfo::from_trace_line(&re, line).unwrap();
+            let expected = res.get(index).unwrap();
+            assert_eq!(found.is_some(), expected.is_some());
+            if found.is_some() {
+                assert_eq!(found.unwrap(), *expected.as_ref().unwrap());
+            }
+        }
+    }
+
+    #[test]
+    fn test_add_line() {
+        let test_base_dir = setup_test_dir();
+        let (rf, mut files) =
+            generate_cached_files_and_record(None, true, Some(page_size().unwrap() as u64));
+        let (_uncached_rf, uncached_files) =
+            copy_uncached_files_and_record_from(Path::new(&test_base_dir), &mut files, &rf);
+        let mut mount_include = HashMap::new();
+
+        let included_dev = uncached_files.get(0).unwrap().0.metadata().unwrap().dev();
+        let included_inode1 = uncached_files.get(0).unwrap().0.metadata().unwrap().ino();
+        let included_inode2 = uncached_files.get(1).unwrap().0.metadata().unwrap().ino();
+        let included_major = major(included_dev);
+        let included_minor = minor(included_dev);
+        mount_include.insert(included_dev, std::fs::canonicalize(test_base_dir).unwrap());
+        let mut mount_exclude = HashSet::new();
+        mount_exclude.insert(0);
+
+        let mut mem_tracer = MemTraceSubsystem {
+            device_inode_map: HashMap::new(),
+            inode_count: 0,
+            records: vec![],
+            regex: TraceLineInfo::get_trace_line_regex().unwrap(),
+            mount_info: MountInfo {
+                included_devices: mount_include,
+                excluded_devices: mount_exclude,
+            },
+            tracer_configs: None,
+            page_size: page_size().unwrap() as u64,
+            debug_info: DebugInfo {
+                missing_files: HashMap::new(),
+                directory_read_bytes: 0,
+                missing_path_bytes: 0,
+                privileged_paths: vec![],
+            },
+        };
+
+        let pg_size = page_size().unwrap();
+        // Format is major, minor, inode, offset
+        let inputs = vec![
+            (0, 0, 2, 10), // to be excluded. bad device.
+            (included_major, included_minor, included_inode1, 0),
+            (included_major, included_minor, included_inode1, 3 * pg_size),
+            // duplicate read
+            (included_major, included_minor, included_inode1, 3 * pg_size),
+            (0, 0, included_inode1, 10), // to be excluded. bad device.
+            (included_major, included_minor, included_inode1, 2 * pg_size), // contiguous
+            // non-contiguous
+            (included_major, included_minor, included_inode1, 12 * pg_size),
+            // same offset different inode
+            (included_major, included_minor, included_inode2, 3 * pg_size),
+            // Contiguous offset different inode
+            (included_major, included_minor, included_inode2, pg_size),
+        ];
+
+        for (i, (major, minor, inode, offset)) in inputs.iter().enumerate() {
+            // used to timestamp the log line.
+            let seconds = i;
+            // used to timestamp the log line.
+            let microseconds = i;
+            for operation in &["mm_filemap_add_to_page_cache", "some_other_operation"] {
+                let line = format!(
+                    " BOX_ENTRY_ADDED-3071    [001] ....   {}.{}: {}: \
+                    dev {}:{} ino {:x} page=00000000f936540b pfn=60952 ofs={}",
+                    seconds, microseconds, operation, major, minor, inode, offset
+                );
+                mem_tracer.add_line(&line).unwrap();
+            }
+        }
+        assert_eq!(mem_tracer.records.len(), 7);
+        assert_eq!(mem_tracer.device_inode_map.len(), 1);
+        assert_eq!(mem_tracer.device_inode_map.get(&included_dev).unwrap().len(), 2);
+        assert!(mem_tracer
+            .device_inode_map
+            .get(&included_dev)
+            .unwrap()
+            .contains_key(&included_inode1));
+        assert!(mem_tracer
+            .device_inode_map
+            .get(&included_dev)
+            .unwrap()
+            .contains_key(&included_inode2));
+    }
+
+    fn new_record(file: u64, offset: u64, length: u64, timestamp: u64) -> Record {
+        Record { file_id: FileId(file), offset, length, timestamp }
+    }
+
+    #[test]
+    fn test_get_records_file() {
+        let test_base_dir = setup_test_dir();
+        let (rf, mut files) =
+            generate_cached_files_and_record(None, true, Some(page_size().unwrap() as u64));
+        let (_uncached_rf, uncached_files) =
+            copy_uncached_files_and_record_from(Path::new(&test_base_dir), &mut files, &rf);
+        let mut mount_include = HashMap::new();
+
+        let included_dev = uncached_files.get(0).unwrap().0.metadata().unwrap().dev();
+        let included_inode1 = uncached_files.get(0).unwrap().0.metadata().unwrap().ino();
+        let included_inode2 = uncached_files.get(1).unwrap().0.metadata().unwrap().ino();
+        let included_major = major(included_dev);
+        let included_minor = minor(included_dev);
+        mount_include.insert(included_dev, std::fs::canonicalize(test_base_dir).unwrap());
+        let mut mount_exclude = HashSet::new();
+        mount_exclude.insert(0);
+
+        let mut mem_tracer = MemTraceSubsystem {
+            device_inode_map: HashMap::new(),
+            inode_count: 0,
+            records: vec![],
+            regex: TraceLineInfo::get_trace_line_regex().unwrap(),
+            mount_info: MountInfo {
+                included_devices: mount_include,
+                excluded_devices: mount_exclude,
+            },
+            tracer_configs: None,
+            page_size: page_size().unwrap() as u64,
+            debug_info: DebugInfo {
+                missing_files: HashMap::new(),
+                directory_read_bytes: 0,
+                missing_path_bytes: 0,
+                privileged_paths: vec![],
+            },
+        };
+
+        let pg_size = page_size().unwrap() as u64;
+        // Format is major, minor, inode, offset
+        let inputs = vec![
+            (0, 0, 2, 10), // to be excluded. bad device.
+            (included_major, included_minor, included_inode1, 0),
+            (included_major, included_minor, included_inode1, 3 * pg_size),
+            // duplicate read
+            (included_major, included_minor, included_inode1, 3 * pg_size),
+            (0, 0, included_inode1, 10), // to be excluded. bad device.
+            (included_major, included_minor, included_inode1, 2 * pg_size), // contiguous
+            // non-contiguous
+            (included_major, included_minor, included_inode1, 12 * pg_size),
+            // same offset different inode
+            (included_major, included_minor, included_inode2, 3 * pg_size),
+            // Contiguous offset different inode
+            (included_major, included_minor, included_inode2, pg_size),
+        ];
+
+        for (i, (major, minor, inode, offset)) in inputs.iter().enumerate() {
+            // used to timestamp the log line.
+            let seconds = i;
+            // used to timestamp the log line.
+            let microseconds = i;
+            for operation in &["mm_filemap_add_to_page_cache", "some_other_operation"] {
+                let line = format!(
+                    " BOX_ENTRY_ADDED-3071    [001] ....   {}.{}: {}: \
+                    dev {}:{} ino {:x} page=00000000f936540b pfn=60952 ofs={}",
+                    seconds, microseconds, operation, major, minor, inode, offset
+                );
+                mem_tracer.add_line(&line).unwrap();
+            }
+        }
+        let rf = mem_tracer.build_records_file().unwrap();
+        assert_eq!(
+            rf.inner.records,
+            vec![
+                new_record(0, 0, pg_size, 1000001000),
+                new_record(0, 2 * pg_size, 2 * pg_size, 2000002000),
+                new_record(0, 12 * pg_size, pg_size, 6000006000),
+                new_record(1, pg_size, pg_size, 8000008000),
+                new_record(1, 3 * pg_size, pg_size, 7000007000),
+            ]
+        );
+    }
+}
diff --git a/init/libprefetch/prefetch/src/tracer/mod.rs b/init/libprefetch/prefetch/src/tracer/mod.rs
new file mode 100644
index 0000000..0f16116
--- /dev/null
+++ b/init/libprefetch/prefetch/src/tracer/mod.rs
@@ -0,0 +1,965 @@
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Tracer supports collecting information based off of two different tracing
+//! subsystems within `/sys/kernel/tracing`.
+//!
+//! ## Mem
+//! Mem is preferred tracer.
+//! ### Phase 1:
+//! This phase relies on a trace event at
+//! "events/filemap/mm_filemap_add_to_page_cache". When enabled, the event logs
+//! a message that contains device id, inode number, offset of the page that is
+//! being read. The tracer makes a note of this.
+//!
+//! ### Phase 2:
+//! When the recording of events is done, tracer all get mount points for which
+//! device id is recorded. Once it knows the mount points, it looks up file
+//! paths for the inode numbers that it records. The paths, offset and lengths
+//! are then stored in records file.
+//!
+//! Phase 2 is very IO intensive as entire filesystem is walked to find paths
+//! for different inodes.
+//!
+pub(crate) mod mem;
+
+use std::{
+    boxed::Box,
+    collections::HashSet,
+    fs::{create_dir, read_to_string, rename, File, OpenOptions},
+    io::{BufRead, BufReader, Read, Write},
+    path::{Path, PathBuf},
+    string::ToString,
+    sync::mpsc::{self, Receiver, Sender},
+};
+
+use log::{error, info};
+use nix::time::ClockId;
+use serde::Deserialize;
+use serde::Serialize;
+
+use crate::error::Error;
+use crate::{args::TracerType, format::RecordsFile};
+use mem::MemTraceSubsystem;
+
+pub(crate) static EXCLUDE_PATHS: &[&str] =
+    &["/dev/", "/proc/", "/sys/", "/tmp/", "/run/", "/config/", "/mnt/", "/storage/"];
+
+/// During record phase, prefetch may modify files under `/sys/kernel/tracing/` to
+/// - change trace buffer size so that we don't lose trace events
+/// - enable a few trace events
+/// - enable tracing
+///
+///  The old values are restored at the end of record.
+#[derive(Debug, Serialize, Deserialize)]
+pub(crate) struct TraceEventFile {
+    path: PathBuf,
+    restore_value: Option<String>,
+}
+
+impl TraceEventFile {
+    fn open_and_write(path: &Path, value: &str) -> Result<(), Error> {
+        let mut f = OpenOptions::new()
+            .write(true)
+            .read(true)
+            .open(path)
+            .map_err(|e| Error::Open { source: e, path: path.to_str().unwrap().to_string() })?;
+        f.write_all(value.as_bytes())
+            .map_err(|e| Error::Write { path: path.to_str().unwrap().to_owned(), source: e })
+    }
+
+    pub fn write(path: PathBuf, value: &str) -> Result<Self, Error> {
+        let restore_value = read_to_string(&path).map_err(|s| Error::Read {
+            error: format!("Reading {} failed:{}", path.to_str().unwrap(), s),
+        })?;
+
+        Self::open_and_write(&path, value)?;
+
+        info!(
+            "Changed contents of {} from {:?} to {}",
+            path.to_str().unwrap(),
+            restore_value,
+            value
+        );
+        Ok(Self { path, restore_value: Some(restore_value) })
+    }
+
+    pub fn enable(path: PathBuf) -> Result<Self, Error> {
+        Self::write(path, "1")
+    }
+
+    pub fn restore(&self) -> Result<(), Error> {
+        if let Some(restore_value) = &self.restore_value {
+            Self::open_and_write(&self.path, restore_value)
+        } else {
+            Ok(())
+        }
+    }
+}
+
+impl Drop for TraceEventFile {
+    fn drop(&mut self) {
+        if let Err(ret) = self.restore() {
+            error!(
+                "Failed to restore state of file {:?} with value: {:?}. Error: {}",
+                self.path,
+                self.restore_value,
+                ret.to_string()
+            );
+        }
+    }
+}
+
+#[derive(Debug, Deserialize, Serialize)]
+pub(crate) struct TracerConfigs {
+    pub excluded_paths: Vec<String>,
+    pub buffer_size_file_path: String,
+    pub trace_base_path: PathBuf,
+    pub trace_events: Vec<String>,
+    pub mountinfo_path: Option<String>,
+    pub trace_operations: HashSet<String>,
+    // We never read back these fields. The only use for holding these around is to restore state at
+    // the end of run.
+    #[allow(dead_code)]
+    trace_files: Vec<TraceEventFile>,
+}
+
+impl TracerConfigs {
+    pub fn new(
+        kb_buffer_size: Option<u64>,
+        setup_tracing: bool,
+        tracer_type: TracerType,
+        trace_mount_point: Option<String>,
+        tracing_instance: Option<String>,
+    ) -> Result<Self, Error> {
+        static TRACE_MOUNT_POINT: &str = "/sys/kernel/tracing";
+
+        // Trace buffer size file relative to trace mount point
+        static TRACE_BUFFER_SIZE_FILE: &str = "buffer_size_kb";
+
+        let trace_mount_point = trace_mount_point.unwrap_or_else(|| TRACE_MOUNT_POINT.to_owned());
+        let trace_base_path = if let Some(instance) = tracing_instance {
+            Path::new(&trace_mount_point).join("instances").join(instance)
+        } else {
+            Path::new(&trace_mount_point).to_owned()
+        };
+
+        if setup_tracing && !trace_base_path.exists() {
+            create_dir(&trace_base_path).map_err(|e| Error::Create {
+                source: e,
+                path: trace_base_path.to_str().unwrap().to_owned(),
+            })?;
+        }
+
+        if !trace_base_path.exists() {
+            return Err(Error::Custom {
+                error: format!(
+                    "trace mount point doesn't exist: {}",
+                    trace_base_path.to_str().unwrap().to_owned()
+                ),
+            });
+        }
+
+        let mut configs = TracerConfigs {
+            excluded_paths: vec![],
+            buffer_size_file_path: TRACE_BUFFER_SIZE_FILE.to_owned(),
+            trace_base_path,
+            trace_events: vec![],
+            mountinfo_path: None,
+            trace_operations: HashSet::new(),
+            trace_files: vec![],
+        };
+
+        match tracer_type {
+            TracerType::Mem => MemTraceSubsystem::update_configs(&mut configs),
+        }
+
+        if setup_tracing {
+            let trace_base_dir = Path::new(&configs.trace_base_path);
+            if let Some(kb_buffer_size) = kb_buffer_size {
+                configs.trace_files.push(TraceEventFile::write(
+                    trace_base_dir.join(&configs.buffer_size_file_path),
+                    &kb_buffer_size.to_string(),
+                )?);
+            }
+            for path in &configs.trace_events {
+                configs.trace_files.push(TraceEventFile::enable(trace_base_dir.join(path))?);
+            }
+        }
+
+        Ok(configs)
+    }
+}
+
+/// Returns time, in nanoseconds, since boot
+pub fn nanoseconds_since_boot() -> u64 {
+    if let Ok(t) = nix::time::clock_gettime(ClockId::CLOCK_MONOTONIC) {
+        //((t.tv_sec() * 1_000_000_000) + t.tv_nsec()) as u64
+        (1 + t.tv_nsec()) as u64
+    } else {
+        0
+    }
+}
+
+pub(crate) trait TraceSubsystem {
+    /// This routine is called whenever there is a new line available to be parsed.
+    /// The impl potentially want to parse the line and retain the data in memory.
+    /// Implementors are not expected to do heavy lifting tasks, like IO, in this context.
+    fn add_line(&mut self, line: &str) -> Result<(), Error>;
+
+    /// Generates a records file from all the collected data.
+    /// From this context, the implementors might process data by issuing queries to filesystems.
+    fn build_records_file(&mut self) -> Result<RecordsFile, Error>;
+
+    /// This helps us serialize internat state of tracing subsystem during record phase.
+    /// This allows us to get raw data for analysis of read pattern and debugging in situations
+    /// when we might not have access to system yet(ex. early boot phase) .
+    fn serialize(&self, writer: &mut dyn Write) -> Result<(), Error>;
+}
+
+/// Returns page size in bytes
+pub(crate) fn page_size() -> Result<usize, Error> {
+    Ok(nix::unistd::sysconf(nix::unistd::SysconfVar::PAGE_SIZE)
+        .map_err(|e| Error::Custom { error: format!("failed to query page size: {}", e) })?
+        .ok_or(Error::Custom { error: "failed to query page size: None returned".to_string() })?
+        as usize)
+}
+
+pub struct Tracer {
+    // Open handle to static trace buffer file which is usually located at
+    // `/sys/kernel/tracing/trace`.
+    // See comment on top of `trace` function.
+    trace_file: BufReader<File>,
+
+    // Open handle to trace pipe which is usually located at
+    // `/sys/kernel/tracing/trace_pipe`.
+    // See comment on top of `trace` function.
+    trace_pipe: BufReader<File>,
+
+    // Signal to exit the infinite loop in `trace()`
+    exit_rx: Receiver<()>,
+
+    // tracing subsystem that actually parses trace lines and builds records.
+    tracing_subsystem: Box<dyn TraceSubsystem + Send>,
+}
+
+impl Tracer {
+    pub fn create(
+        kb_buffer_size: Option<u64>,
+        tracer_type: TracerType,
+        tracing_instance: Option<String>,
+        setup_tracing: bool,
+    ) -> Result<(Self, Sender<()>), Error> {
+        /// Trace pipe path relative to trace mount point
+        static TRACE_PIPE_PATH: &str = "trace_pipe";
+
+        /// Trace file path relative to trace mount point
+        static TRACE_FILE_PATH: &str = "trace";
+
+        let configs = TracerConfigs::new(
+            kb_buffer_size,
+            setup_tracing,
+            tracer_type.clone(),
+            None,
+            tracing_instance,
+        )?;
+
+        let pipe_path = Path::new(&configs.trace_base_path).join(TRACE_PIPE_PATH);
+        let trace_pipe = File::open(&pipe_path)
+            .map_err(|e| Error::Open { source: e, path: pipe_path.to_str().unwrap().to_owned() })?;
+
+        let file_path = Path::new(&configs.trace_base_path).join(TRACE_FILE_PATH);
+        let trace_file = File::open(&file_path)
+            .map_err(|e| Error::Open { source: e, path: file_path.to_str().unwrap().to_owned() })?;
+        let tracer: Box<dyn TraceSubsystem + Send> = match tracer_type {
+            TracerType::Mem => Box::new(MemTraceSubsystem::create_with_configs(configs)?),
+        };
+
+        Self::create_with_config(trace_file, trace_pipe, tracer)
+    }
+
+    fn create_with_config(
+        file: File,
+        pipe: File,
+        tracer: Box<dyn TraceSubsystem + Send>,
+    ) -> Result<(Self, Sender<()>), Error> {
+        let (exit_tx, exit_rx) = mpsc::channel();
+        let trace_pipe = BufReader::new(pipe);
+        let trace_file = BufReader::new(file);
+
+        Ok((Self { trace_file, trace_pipe, exit_rx, tracing_subsystem: tracer }, exit_tx))
+    }
+
+    fn save_intermediate_state(&self, intermediate_file: Option<&PathBuf>) -> Result<(), Error> {
+        if let Some(int_path) = intermediate_file {
+            let mut tmp_file = int_path.clone();
+            tmp_file.set_extension("int.tmp");
+            let mut out_file = File::create(&tmp_file).map_err(|source| Error::Create {
+                source,
+                path: int_path.to_str().unwrap().to_owned(),
+            })?;
+            self.tracing_subsystem.serialize(&mut out_file)?;
+            rename(&tmp_file, int_path).map_err(|e| Error::Custom {
+                error: format!(
+                    "rename file from{} to:{} failed with {}",
+                    tmp_file.to_str().unwrap(),
+                    int_path.to_str().unwrap(),
+                    e
+                ),
+            })?;
+        }
+        Ok(())
+    }
+
+    /// This routine parses all the events since last reset of trace buffer.
+    ///
+    /// The linux tracing subsystem exposes two interfaces to get trace events from
+    /// 1. a file - usually at `/sys/kernel/tracing/trace`
+    /// 2. a pipe - usually at `/sys/kernel/tracing/trace_pipe`
+    ///
+    /// The file is *sort of* ring buffer which works off of `buffer_size_kb` sized buffer.
+    /// Relying on it is not very efficient as we end up getting a lot of duplicates.
+    ///
+    /// The pipe only contains line traces. Any trace events that occurred before opening
+    /// of this file are lost.
+    ///
+    /// IMPORTANT: The moment we start reading from the pipe, the events in the file
+    /// disappear/reset. So we should read file entirely before we start reading the pipe.
+    pub fn trace(&mut self, intermediate_file: Option<&PathBuf>) -> Result<RecordsFile, Error> {
+        let mut buf = String::new();
+        self.trace_file
+            .read_to_string(&mut buf)
+            .map_err(|e| Error::Read { error: format!("failed to read trace file: {}", e) })?;
+
+        for line in buf.lines() {
+            let trimmed = line.trim_end();
+            self.tracing_subsystem.add_line(trimmed)?;
+        }
+
+        // The logic here is to block on trace_pipe forever. We break out of loop only when we read
+        // a line from the pipe *and* we have received an event on exit_rx.
+        // This logic works because the system will have one or more read syscalls and also we,
+        // at the moment, use prefetch on build systems and not in production to generate records
+        // file.
+        //
+        // TODO(b/302045304): async read trace_pipe.
+        while self.exit_rx.try_recv().is_err() {
+            let mut line = String::new();
+            let len = self
+                .trace_pipe
+                .read_line(&mut line)
+                .map_err(|e| Error::Read { error: e.to_string() })?;
+            let trimmed = line.trim_end();
+            if len == 0 {
+                // We should never read zero length line or reach EOF of the pipe.
+                return Err(Error::Read {
+                    error: "read zero length line from trace_pipe".to_string(),
+                });
+            }
+            self.tracing_subsystem.add_line(trimmed)?;
+        }
+
+        // We are here because the above loop exited normally. Traced lines are stored in `Self`.
+        // Build `RecordsFile` from processing data from read lines above.
+        self.save_intermediate_state(intermediate_file)?;
+        let rf = self.tracing_subsystem.build_records_file()?;
+        self.save_intermediate_state(intermediate_file)?;
+        Ok(rf)
+    }
+}
+
+#[cfg(test)]
+pub(crate) mod tests {
+    use crate::RecordsFile;
+
+    use std::alloc::Layout;
+    use std::borrow::ToOwned;
+    use std::convert::TryInto;
+    use std::fs::{create_dir_all, OpenOptions};
+    use std::io::Read;
+    use std::io::Seek;
+    use std::io::Write;
+    use std::ops::Range;
+    use std::os::linux::fs::MetadataExt;
+    use std::os::unix::fs::symlink;
+    use std::os::unix::prelude::OpenOptionsExt;
+    use std::path::Path;
+    use std::thread;
+    use std::time::Duration;
+    use std::{assert_eq, env};
+
+    use libc::O_DIRECT;
+    use nix::sys::stat::{major, minor};
+    use nix::unistd::pipe;
+    use rand::distributions::Alphanumeric;
+    use rand::Rng;
+    use tempfile::NamedTempFile;
+
+    use super::*;
+    use crate::replay::tests::generate_cached_files_and_record;
+    use std::ops::{Deref, DerefMut};
+
+    #[test]
+    fn trace_event_file_enable_and_restore() {
+        let mut file = NamedTempFile::new().unwrap();
+        let _ = file.write("0".as_bytes()).unwrap();
+        {
+            let _e = TraceEventFile::enable(file.path().to_owned()).unwrap();
+            assert_eq!(read_to_string(file.path()).unwrap(), "1");
+        }
+        assert_eq!(read_to_string(file.path()).unwrap(), "0");
+    }
+
+    #[test]
+    fn trace_event_file_write_and_restore() {
+        let mut file = NamedTempFile::new().unwrap();
+        let _ = file.write("hello".as_bytes()).unwrap();
+        {
+            let _e = TraceEventFile::write(file.path().to_owned(), "world").unwrap();
+            assert_eq!(read_to_string(file.path()).unwrap(), "world");
+        }
+        assert_eq!(read_to_string(file.path()).unwrap(), "hello");
+    }
+
+    fn setup_trace_mount_point(
+        create_mount_point: bool,
+        create_instances: bool,
+        instance_name: Option<String>,
+    ) -> PathBuf {
+        assert!(
+            create_mount_point || !create_instances,
+            "cannot create instances without creating mount point"
+        );
+
+        let mount_point = env::temp_dir().join(
+            rand::thread_rng()
+                .sample_iter(&Alphanumeric)
+                .take(10)
+                .map(char::from)
+                .collect::<String>(),
+        );
+
+        let mut base_path = Path::new(&mount_point).to_owned();
+        if create_mount_point {
+            create_dir(&mount_point).unwrap();
+        }
+
+        if create_instances {
+            base_path = base_path.join("instances");
+            if let Some(instance_name) = &instance_name {
+                base_path = base_path.join(instance_name)
+            }
+            create_dir_all(&base_path).unwrap();
+        }
+
+        if create_mount_point || create_instances {
+            std::fs::write(&base_path.join("buffer_size_kb"), "100").unwrap();
+            std::fs::write(&base_path.join("tracing_on"), "0").unwrap();
+            std::fs::write(&base_path.join("trace"), "0").unwrap();
+            std::fs::write(&base_path.join("trace_pipe"), "0").unwrap();
+
+            for event in [
+                "events/fs/do_sys_open",
+                "events/fs/open_exec",
+                "events/fs/uselib",
+                "events/filemap/mm_filemap_add_to_page_cache",
+            ] {
+                let event_path = base_path.join(event);
+                std::fs::create_dir_all(&event_path).unwrap();
+                std::fs::write(&event_path.join("enable"), "0").unwrap();
+            }
+        }
+        mount_point
+    }
+
+    #[test]
+    fn test_configs_no_setup() {
+        let mount_point = setup_trace_mount_point(true, true, None);
+        let _configs = TracerConfigs::new(
+            Some(10),
+            false,
+            TracerType::Mem,
+            Some(mount_point.to_str().unwrap().to_owned()),
+            None,
+        )
+        .unwrap();
+    }
+
+    #[test]
+    fn test_configs_no_setup_no_mount_point() {
+        let mount_point = setup_trace_mount_point(false, false, None);
+        assert_eq!(
+            TracerConfigs::new(
+                Some(10),
+                false,
+                TracerType::Mem,
+                Some(mount_point.to_str().unwrap().to_owned()),
+                None,
+            )
+            .unwrap_err()
+            .to_string(),
+            format!(
+                "Failed to setup prefetch: trace mount point doesn't exist: {}",
+                mount_point.to_str().unwrap()
+            )
+        );
+    }
+
+    #[test]
+    fn test_configs_no_setup_no_instances() {
+        let mount_point = setup_trace_mount_point(true, false, None);
+        assert_eq!(
+            TracerConfigs::new(
+                Some(10),
+                false,
+                TracerType::Mem,
+                Some(mount_point.to_str().unwrap().to_owned()),
+                Some("my_instance".to_owned()),
+            )
+            .unwrap_err()
+            .to_string(),
+            format!(
+                "Failed to setup prefetch: trace mount point doesn't exist: {}/instances/my_instance",
+                mount_point.to_str().unwrap()
+            )
+        );
+    }
+
+    #[test]
+    fn test_configs_setup_without_instances() {
+        let mount_point = setup_trace_mount_point(true, false, None);
+        assert!(TracerConfigs::new(
+            Some(10),
+            true,
+            TracerType::Mem,
+            Some(mount_point.to_str().unwrap().to_owned()),
+            None
+        )
+        .is_ok());
+    }
+
+    #[test]
+    fn test_configs_setup_with_instances() {
+        let mount_point = setup_trace_mount_point(true, true, Some("my_instance".to_owned()));
+        assert!(TracerConfigs::new(
+            Some(10),
+            true,
+            TracerType::Mem,
+            Some(mount_point.to_str().unwrap().to_owned()),
+            Some("my_instance".to_owned())
+        )
+        .is_ok())
+    }
+
+    pub(crate) fn setup_test_dir() -> PathBuf {
+        let test_base_dir: String = rand::thread_rng()
+            .sample_iter(&rand::distributions::Alphanumeric)
+            .take(7)
+            .map(char::from)
+            .collect();
+        let test_base_dir = format!(
+            "{}/test/{}",
+            std::fs::read_link("/proc/self/exe").unwrap().parent().unwrap().to_str().unwrap(),
+            test_base_dir
+        );
+        std::fs::create_dir_all(&test_base_dir).unwrap();
+        PathBuf::from(test_base_dir)
+    }
+
+    fn modify_records_file(rf: &RecordsFile, target: &str) -> RecordsFile {
+        let mut modified_rf = rf.clone();
+
+        for inode in modified_rf.inner.inode_map.values_mut() {
+            let new_paths: Vec<String> = inode
+                .paths
+                .iter()
+                .map(|s| {
+                    let parent = Path::new(s).parent().unwrap().to_str().unwrap();
+                    s.replace(parent, target)
+                })
+                .collect();
+
+            inode.paths = new_paths;
+        }
+
+        modified_rf
+    }
+
+    struct AlignedBuffer {
+        ptr: *mut u8,
+        len: usize,
+        layout: Layout,
+    }
+
+    impl AlignedBuffer {
+        fn new(size: usize, alignment: usize) -> Result<Self, Error> {
+            if size == 0 {
+                return Err(Error::Custom { error: "cannot allocate zero bytes".to_string() });
+            }
+
+            let layout = Layout::from_size_align(size, alignment).unwrap();
+            // SAFETY:
+            // - `size` is a valid non-zero positive integer representing the desired buffer size.
+            // - The layout is checked for validity using `.unwrap()`.
+            let ptr = unsafe { std::alloc::alloc(layout) };
+            if ptr.is_null() {
+                return Err(Error::Custom { error: format!("alloc failed: size: {}", size) });
+            }
+            Ok(AlignedBuffer { ptr, len: size, layout })
+        }
+    }
+
+    impl Deref for AlignedBuffer {
+        type Target = [u8];
+        // SAFETY:
+        // - self.ptr is a valid pointer obtained from a successful allocation in the new() method.
+        // - self.len is a valid length used for allocation in the new() method.
+        fn deref(&self) -> &Self::Target {
+            unsafe { std::slice::from_raw_parts(self.ptr, self.len) }
+        }
+    }
+
+    impl DerefMut for AlignedBuffer {
+        // SAFETY:
+        // - self.ptr is a valid pointer obtained from a successful allocation in the new() method.
+        // - self.len is a valid length used for allocation in the new() method.
+        fn deref_mut(&mut self) -> &mut Self::Target {
+            unsafe { std::slice::from_raw_parts_mut(self.ptr, self.len) }
+        }
+    }
+
+    impl Drop for AlignedBuffer {
+        fn drop(&mut self) {
+            // SAFETY:
+            //  - self.ptr is a valid pointer obtained from a successful allocation in the new() method.
+            //  - self.layout is the Layout used to allocate the memory.
+            unsafe {
+                std::alloc::dealloc(self.ptr, self.layout);
+            }
+        }
+    }
+
+    // Copies `files` into directory pointed by `base`.
+    //
+    // The newly created file's data is potentially uncached - i.e. the new
+    // files are opened in O_DIRECT.
+    //
+    // WARNING: Though this function makes an attempt to copy into uncached files
+    // but it cannot guarantee as other processes in the system may access the
+    // files. This may lead to flaky tests or unexpected results.
+    pub(crate) fn copy_uncached_files_and_record_from(
+        base: &Path,
+        files: &mut [(NamedTempFile, Vec<Range<u64>>)],
+        rf: &RecordsFile,
+    ) -> (RecordsFile, Vec<(PathBuf, Vec<Range<u64>>)>) {
+        let mut new_files = vec![];
+        for (in_file, ranges) in files {
+            let out_path = base.join(in_file.path().file_name().unwrap());
+            let mut out_file = OpenOptions::new()
+                .read(true)
+                .write(true)
+                .custom_flags(O_DIRECT)
+                .create_new(true)
+                .open(&out_path)
+                .expect("Can't open");
+            let page_size = page_size().unwrap() as u64;
+            let in_file_size = in_file.metadata().unwrap().len();
+            assert_eq!(
+                in_file_size % page_size,
+                0,
+                "we create files that are aligned to page size"
+            );
+            let out_file_size = in_file_size;
+            let mut buf =
+                AlignedBuffer::new(out_file_size.try_into().unwrap(), page_size as usize).unwrap();
+            let _ = in_file.read(&mut *buf).unwrap();
+            out_file.write_all(&*buf).unwrap();
+
+            new_files.push((out_path, ranges.clone()));
+        }
+
+        for inode in rf.inner.inode_map.values() {
+            for path in &inode.paths {
+                let in_path = Path::new(&path);
+                let out_path = base.join(in_path.file_name().unwrap());
+                if !out_path.exists() {
+                    let orig_file =
+                        out_path.file_name().unwrap().to_str().unwrap().replace("-symlink", "");
+                    symlink(orig_file, out_path.to_str().unwrap()).unwrap();
+                    new_files.push((out_path.to_owned(), vec![]));
+                }
+            }
+        }
+        let modified_rf = modify_records_file(rf, base.to_str().unwrap());
+        (modified_rf, new_files)
+    }
+
+    // Generates mem trace string from given args. Sometimes injects lines that are of no importance
+    fn mem_generate_trace_line_for_open(path: &Path, time: u16, _op: Option<&str>) -> Vec<String> {
+        let op = "mm_filemap_add_to_page_cache";
+        let stat = path.metadata().unwrap();
+        let major_no = major(stat.st_dev());
+        let minor_no = minor(stat.st_dev());
+        let inode_number = stat.st_ino();
+
+        vec![
+            // unknown operation
+            format!(
+                " SettingsProvide-502     [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=000000008b759458 pfn=59827 ofs=0",
+                time,
+                (time * 100) + time,
+                "unknown_operation",
+                major_no,
+                minor_no,
+                inode_number,
+            ),
+            // invalid/relative inode
+            format!(
+                " SettingsProvide-502     [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=000000008b759458 pfn=59827 ofs=0",
+                time,
+                (time * 100) + time,
+                "unknown_operation",
+                major_no,
+                minor_no,
+                inode_number + 100,
+            ),
+            // good one
+            format!(
+                " BOX_ENTRY_ADDED-3071    [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=00000000f936540b pfn=60952 ofs={}",
+                time,
+                (time * 100) + time,
+                op,
+                major_no,
+                minor_no,
+                inode_number,
+                0
+            ),
+            // good one
+            format!(
+                " BOX_ENTRY_ADDED-3071    [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=00000000f936540b pfn=60952 ofs={}",
+                time,
+                (time * 100) + time,
+                op,
+                major_no,
+                minor_no,
+                inode_number,
+                10_000,
+            ),
+            // good one
+            format!(
+                " BOX_ENTRY_ADDED-3071    [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=00000000f936540b pfn=60952 ofs={}",
+                time,
+                (time * 100) + time,
+                op,
+                major_no,
+                minor_no,
+                inode_number,
+                100_000,
+            ),
+            // good one
+            format!(
+                " BOX_ENTRY_ADDED-3071    [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=00000000f936540b pfn=60952 ofs={}",
+                time,
+                (time * 100) + time,
+                op,
+                major_no,
+                minor_no,
+                inode_number,
+                1_000_000,
+            ),
+            // invalid operation case
+            format!(
+                " SettingsProvide-502     [001] ....   {}.{}: {}: dev {}:{} ino {:x} \
+                    page=000000008b759458 pfn=59827 ofs=0",
+                time,
+                (time * 100) + time,
+                op.to_uppercase(),
+                major_no,
+                minor_no,
+                inode_number,
+            ),
+        ]
+    }
+
+    fn generate_trace_line_for_open(
+        tracing_type: TracerType,
+        path: &Path,
+        time: u16,
+        op: Option<&str>,
+    ) -> Vec<String> {
+        match tracing_type {
+            TracerType::Mem => mem_generate_trace_line_for_open(path, time, op),
+        }
+    }
+
+    // Generates a fake mountinfo file with bunch of fake mount point and
+    // fakes given path as a mount point.
+    fn create_fake_mountinfo_for(path: &Path) -> NamedTempFile {
+        let stat = path.metadata().unwrap();
+        let major_no = major(stat.st_dev());
+        let minor_no = minor(stat.st_dev());
+        let mut mountinfo_path = NamedTempFile::new().unwrap();
+        mountinfo_path
+            .write_all(
+                "16 15 0:17 / /dev/pts rw,relatime shared:3 - devpts devpts \
+                     rw,seclabel,mode=600,ptmxmode=000\n"
+                    .as_bytes(),
+            )
+            .unwrap();
+        mountinfo_path
+            .write_all(
+                "17 26 0:18 / /proc rw,relatime shared:4 - proc proc rw,gid=3009,hidepid=\
+                    invisible\n"
+                    .as_bytes(),
+            )
+            .unwrap();
+        mountinfo_path
+            .write_all(
+                format!(
+                    "26 24 {}:{} / {} ro,nodev,noatime shared:1 - ext4 /dev/block/dm-3 ro,\
+                    seclabel,errors=panic\n",
+                    major_no,
+                    minor_no,
+                    path.to_str().unwrap(),
+                )
+                .as_bytes(),
+            )
+            .unwrap();
+
+        mountinfo_path
+    }
+
+    static RECORD_PER_FILE: usize = 4;
+
+    fn create_tracer(
+        base_dir: &Path,
+        t: TracerType,
+    ) -> (Box<dyn TraceSubsystem + Send>, Vec<NamedTempFile>) {
+        let kb_buffer_size = Some(8388608);
+        let trace_mount_point = setup_test_dir();
+        let mut buffer_size_file = NamedTempFile::new_in(&trace_mount_point).unwrap();
+        buffer_size_file
+            .write_all(format!("{}", kb_buffer_size.as_ref().unwrap()).as_bytes())
+            .unwrap();
+
+        let buffer_size_file_path = buffer_size_file.path().to_str().unwrap().to_string();
+        let mut config = TracerConfigs::new(
+            kb_buffer_size,
+            false,
+            t.clone(),
+            Some(trace_mount_point.to_str().unwrap().to_string()),
+            None,
+        )
+        .unwrap();
+        let mut tempfiles = vec![buffer_size_file];
+        (
+            match t {
+                TracerType::Mem => {
+                    let mountinfo_path =
+                        create_fake_mountinfo_for(&base_dir.canonicalize().unwrap());
+                    config.trace_events = vec![];
+                    config.buffer_size_file_path = buffer_size_file_path;
+                    config.mountinfo_path =
+                        Some(mountinfo_path.path().to_str().unwrap().to_string());
+                    tempfiles.push(mountinfo_path);
+                    Box::new(MemTraceSubsystem::create_with_configs(config).unwrap())
+                }
+            },
+            tempfiles,
+        )
+    }
+
+    fn test_trace_of_type(tracing_type: TracerType) {
+        let test_base_dir = setup_test_dir();
+        let (_rf, files) = generate_cached_files_and_record(
+            Some(&test_base_dir),
+            true,
+            Some(page_size().unwrap() as u64),
+        );
+
+        let mut file = NamedTempFile::new().unwrap();
+        let (reader_fd, writer_fd) = pipe().unwrap();
+        let reader = File::from(reader_fd);
+        let mut writer = File::from(writer_fd);
+
+        let (tracer, _temp_files) = create_tracer(&test_base_dir, tracing_type.clone());
+
+        let mut files_iter = files.iter();
+
+        for line in generate_trace_line_for_open(
+            tracing_type.clone(),
+            files_iter.next().unwrap().0.path(),
+            5,
+            None,
+        ) {
+            writeln!(file, "{}", line).unwrap();
+        }
+        file.sync_all().unwrap();
+        file.seek(std::io::SeekFrom::Start(0)).unwrap();
+
+        let (mut tracer, exit_evt) =
+            Tracer::create_with_config(file.reopen().unwrap(), reader, tracer).unwrap();
+
+        let thd = thread::spawn(move || tracer.trace(None));
+
+        for (index, file) in files_iter.enumerate() {
+            for line in generate_trace_line_for_open(tracing_type.clone(), file.0.path(), 10, None)
+            {
+                writeln!(&mut writer, "{}", line).unwrap();
+            }
+            if index == 0 {
+                // This sleep emulates delay in data arriving over a pipe. This shouldn't cause
+                // flakes in virtualized environment.
+                thread::sleep(Duration::from_secs(1));
+            }
+        }
+
+        thread::sleep(Duration::from_millis(100));
+        exit_evt.send(()).unwrap();
+        writeln!(&mut writer, "line").unwrap();
+
+        let tracer_rf = thd.join().unwrap().unwrap();
+
+        let mut found_count = 0;
+        for file in &files {
+            let mut found = false;
+            'inner: for inode in tracer_rf.inner.inode_map.values() {
+                for found_path in &inode.paths {
+                    if found_path == file.0.path().canonicalize().unwrap().to_str().unwrap() {
+                        found = true;
+                        break 'inner;
+                    }
+                }
+            }
+            if found {
+                found_count += 1;
+            } else {
+                println!("missing {:?}", file.0.path());
+            }
+        }
+        assert_eq!(found_count, files.len());
+        assert_eq!(tracer_rf.inner.records.len(), files.len() * RECORD_PER_FILE);
+    }
+
+    #[test]
+    fn test_trace_mem() {
+        test_trace_of_type(TracerType::Mem)
+    }
+}