libprefetch: replay/record checks if they can run on its own
Currently, prefetch `record` or `replay` command is executed
when the respective property is set, which is done by `start`
command. However, due to the timing of which property trigger
gets executed, this results in prefetch not starting neither
`record` or `replay` until the very end of boot phase.
Instead of going through `start` to determine which command
to run using property, each command will check whether they
can execute on their own. this way we can tweak exactly when
we want to run each commands.
Bug: 380766679
Test: Builds
Test: On cuttlefish, observe replay correctly exiting when
replay condition is not met.
Test: On cuttlefish, observe record correctly exiting when
record condition is not met.
Change-Id: Iad926450f00984d703f72c9c7b1876a0b3d3ecfd
diff --git a/init/libprefetch/prefetch/prefetch.rc b/init/libprefetch/prefetch/prefetch.rc
index dee37bb..bdcbbc6 100644
--- a/init/libprefetch/prefetch/prefetch.rc
+++ b/init/libprefetch/prefetch/prefetch.rc
@@ -1,28 +1,36 @@
-on init && property:ro.prefetch_boot.enabled=true
- start prefetch
-
-service prefetch /system/bin/prefetch start
- class main
- user root
- group root system
- disabled
- oneshot
-
-on property:prefetch_boot.record=true
- start prefetch_record
+# Reads data from disk in advance and populates page cache
+# to speed up subsequent disk access.
+#
+# Record:
+# start by `start prefetch_record` at appropriate timing.
+# stop by setting `prefetch_boot.record_stop` to 1.
+# set --duration to only capture for a certain duration instead.
+#
+# Replay:
+# start by `start prefetch_replay` at appropriate timing.
+# it will depend on several files generated from record.
+#
+# replay is I/O intensive. make sure you pick appropriate
+# timing to run each, so that you can maximize the page cache
+# hit for subsequent disk access.
+#
+# Example:
+# on early-init && property:ro.prefetch_boot.enabled=true
+# start prefetch_replay
+#
+# on init && property:ro.prefetch_boot.enabled=true
+# start prefetch_record
+#
+# on property:sys.boot_completed=1 && property:ro.prefetch_boot.enabled=true
+# setprop prefetch_boot.record_stop 1
service prefetch_record /system/bin/prefetch record --duration ${ro.prefetch_boot.duration_s:-0}
- class main
user root
group root system
disabled
oneshot
-on property:prefetch_boot.replay=true
- start prefetch_replay
-
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
diff --git a/init/libprefetch/prefetch/src/arch/android.rs b/init/libprefetch/prefetch/src/arch/android.rs
index a11767e..90db6c9 100644
--- a/init/libprefetch/prefetch/src/arch/android.rs
+++ b/init/libprefetch/prefetch/src/arch/android.rs
@@ -6,6 +6,7 @@
use std::fs::File;
use std::fs::OpenOptions;
use std::io::Write;
+use std::path::Path;
use std::time::Duration;
use rustutils::system_properties::error::PropertyWatcherError;
@@ -41,6 +42,43 @@
Ok(())
}
+/// Checks if we can perform replay phase.
+/// Ensure that the pack file exists and is up-to-date, returns false otherwise.
+pub fn can_perform_replay(pack_path: &Path, fingerprint_path: &Path) -> Result<bool, Error> {
+ if !pack_path.exists() || !fingerprint_path.exists() {
+ return Ok(false);
+ }
+
+ let saved_fingerprint = std::fs::read_to_string(fingerprint_path)?;
+
+ let current_device_fingerprint = rustutils::system_properties::read("ro.build.fingerprint")
+ .map_err(|e| Error::Custom {
+ error: format!("Failed to read ro.build.fingerprint: {}", e),
+ })?;
+
+ Ok(current_device_fingerprint.is_some_and(|fp| fp == saved_fingerprint.trim()))
+}
+
+/// Checks if we can perform record phase.
+/// Ensure that following conditions hold:
+/// - File specified in ready_path exists. otherwise, create a new file and return false.
+/// - can_perform_replay is false.
+pub fn ensure_record_is_ready(
+ ready_path: &Path,
+ pack_path: &Path,
+ fingerprint_path: &Path,
+) -> Result<bool, Error> {
+ if !ready_path.exists() {
+ File::create(ready_path)
+ .map_err(|_| Error::Custom { error: "File Creation failed".to_string() })?;
+
+ return Ok(false);
+ }
+
+ let can_replay = can_perform_replay(pack_path, fingerprint_path)?;
+ Ok(!can_replay)
+}
+
/// Start prefetch service
///
/// 1: Check the presence of the file 'prefetch_ready'. If it doesn't
diff --git a/init/libprefetch/prefetch/src/args/args_argh.rs b/init/libprefetch/prefetch/src/args/args_argh.rs
index 65084ee..b047d0f 100644
--- a/init/libprefetch/prefetch/src/args/args_argh.rs
+++ b/init/libprefetch/prefetch/src/args/args_argh.rs
@@ -147,6 +147,13 @@
/// store build_finger_print to tie the pack format
#[argh(option, default = "default_build_finger_print_path()")]
pub build_fingerprint_path: PathBuf,
+
+ #[cfg(target_os = "android")]
+ /// file path to check if prefetch_ready is present.
+ ///
+ /// A new file is created at the given path if it's not present.
+ #[argh(option, default = "default_ready_path()")]
+ pub ready_path: PathBuf,
}
/// Type of tracing subsystem to use.
@@ -204,6 +211,11 @@
/// file path from where the prefetch config file will be read
#[argh(option, default = "PathBuf::new()")]
pub config_path: PathBuf,
+
+ #[cfg(target_os = "android")]
+ /// store build_finger_print to tie the pack format
+ #[argh(option, default = "default_build_finger_print_path()")]
+ pub build_fingerprint_path: PathBuf,
}
/// dump records file in given format
diff --git a/init/libprefetch/prefetch/src/lib.rs b/init/libprefetch/prefetch/src/lib.rs
index 6564c4b..8286ef4 100644
--- a/init/libprefetch/prefetch/src/lib.rs
+++ b/init/libprefetch/prefetch/src/lib.rs
@@ -59,6 +59,13 @@
/// Records prefetch data for the given configuration
pub fn record(args: &RecordArgs) -> Result<(), Error> {
+ #[cfg(target_os = "android")]
+ if !ensure_record_is_ready(&args.ready_path, &args.path, &args.build_fingerprint_path)? {
+ info!("Cannot perform record -- skipping");
+ return Ok(());
+ }
+
+ info!("Starting record.");
let (mut tracer, exit_tx) = tracer::Tracer::create(
args.trace_buffer_size_kib,
args.tracing_subsystem.clone(),
@@ -109,6 +116,13 @@
/// Replays prefetch data for the given configuration
pub fn replay(args: &ReplayArgs) -> Result<(), Error> {
+ #[cfg(target_os = "android")]
+ if !can_perform_replay(&args.path, &args.build_fingerprint_path)? {
+ info!("Cannot perform replay -- exiting.");
+ return Ok(());
+ }
+
+ info!("Starting replay.");
let replay = Replay::new(args)?;
replay.replay()
}