Support ZSTD in userspace COW
Perf:
Lz4:
Update took 429 seconds
merge time 35.4s
cow size: 3.18GB
ZSTD:
Update took 676 seconds
merge time 49.4s
cow size: 2.62GB
Gz:
Update took 1057 seconds
merge time: 50.0s
cow size: 2.55GB
In summary, ZSTD is a middle point between LZ4 and GZ.
Speed: LZ4 > ZSTD > GZ
Space: LZ4 > ZSTD > GZ
Bug: 274129758
Change-Id: I203bf088b7c2a9ce429f75478799da0e7126febf
diff --git a/fastboot/Android.bp b/fastboot/Android.bp
index 7794c4b..56cac88 100644
--- a/fastboot/Android.bp
+++ b/fastboot/Android.bp
@@ -196,6 +196,7 @@
"libfastbootshim",
"libsnapshot_cow",
"liblz4",
+ "libzstd",
"libsnapshot_nobinder",
"update_metadata-protos",
"liburing",
diff --git a/fs_mgr/libsnapshot/Android.bp b/fs_mgr/libsnapshot/Android.bp
index 3dd1f1a..d3bd904 100644
--- a/fs_mgr/libsnapshot/Android.bp
+++ b/fs_mgr/libsnapshot/Android.bp
@@ -163,6 +163,7 @@
"libbrotli",
"libz",
"liblz4",
+ "libzstd",
],
export_include_dirs: ["include"],
}
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index 6baf4be..c3ca00a 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -157,7 +157,8 @@
kCowCompressNone = 0,
kCowCompressGz = 1,
kCowCompressBrotli = 2,
- kCowCompressLz4 = 3
+ kCowCompressLz4 = 3,
+ kCowCompressZstd = 4,
};
static constexpr uint8_t kCowReadAheadNotStarted = 0;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
index d06c904..a4a0ad6 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_compress.cpp
@@ -29,6 +29,7 @@
#include <libsnapshot/cow_writer.h>
#include <lz4.h>
#include <zlib.h>
+#include <zstd.h>
namespace android {
namespace snapshot {
@@ -40,6 +41,8 @@
return {kCowCompressBrotli};
} else if (name == "lz4") {
return {kCowCompressLz4};
+ } else if (name == "zstd") {
+ return {kCowCompressZstd};
} else if (name == "none" || name.empty()) {
return {kCowCompressNone};
} else {
@@ -112,6 +115,23 @@
}
return buffer;
}
+ case kCowCompressZstd: {
+ std::basic_string<uint8_t> buffer(ZSTD_compressBound(length), '\0');
+ const auto compressed_size =
+ ZSTD_compress(buffer.data(), buffer.size(), data, length, 0);
+ if (compressed_size <= 0) {
+ LOG(ERROR) << "ZSTD compression failed " << compressed_size;
+ return {};
+ }
+ // Don't run compression if the compressed output is larger
+ if (compressed_size >= length) {
+ buffer.resize(length);
+ memcpy(buffer.data(), data, length);
+ } else {
+ buffer.resize(compressed_size);
+ }
+ return buffer;
+ }
default:
LOG(ERROR) << "unhandled compression type: " << compression;
break;
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
index 3d34413..da90cc0 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.cpp
@@ -17,12 +17,15 @@
#include "cow_decompress.h"
#include <array>
+#include <cstring>
#include <utility>
+#include <vector>
#include <android-base/logging.h>
#include <brotli/decode.h>
#include <lz4.h>
#include <zlib.h>
+#include <zstd.h>
namespace android {
namespace snapshot {
@@ -336,9 +339,56 @@
}
};
+class ZstdDecompressor final : public IDecompressor {
+ public:
+ ssize_t Decompress(void* buffer, size_t buffer_size, size_t decompressed_size,
+ size_t ignore_bytes = 0) override {
+ if (buffer_size < decompressed_size - ignore_bytes) {
+ LOG(INFO) << "buffer size " << buffer_size
+ << " is not large enough to hold decompressed data. Decompressed size "
+ << decompressed_size << ", ignore_bytes " << ignore_bytes;
+ return -1;
+ }
+ if (ignore_bytes == 0) {
+ if (!Decompress(buffer, decompressed_size)) {
+ return -1;
+ }
+ return decompressed_size;
+ }
+ std::vector<unsigned char> ignore_buf(decompressed_size);
+ if (!Decompress(buffer, decompressed_size)) {
+ return -1;
+ }
+ memcpy(buffer, ignore_buf.data() + ignore_bytes, buffer_size);
+ return decompressed_size;
+ }
+ bool Decompress(void* output_buffer, const size_t output_size) {
+ std::string input_buffer;
+ input_buffer.resize(stream_->Size());
+ size_t bytes_read = stream_->Read(input_buffer.data(), input_buffer.size());
+ if (bytes_read != input_buffer.size()) {
+ LOG(ERROR) << "Failed to read all input at once. Expected: " << input_buffer.size()
+ << " actual: " << bytes_read;
+ return false;
+ }
+ const auto bytes_decompressed = ZSTD_decompress(output_buffer, output_size,
+ input_buffer.data(), input_buffer.size());
+ if (bytes_decompressed != output_size) {
+ LOG(ERROR) << "Failed to decompress ZSTD block, expected output size: " << output_size
+ << ", actual: " << bytes_decompressed;
+ return false;
+ }
+ return true;
+ }
+};
+
std::unique_ptr<IDecompressor> IDecompressor::Lz4() {
return std::make_unique<Lz4Decompressor>();
}
+std::unique_ptr<IDecompressor> IDecompressor::Zstd() {
+ return std::make_unique<ZstdDecompressor>();
+}
+
} // namespace snapshot
} // namespace android
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h
index 9e83f3c..52b3d76 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_decompress.h
@@ -47,6 +47,7 @@
static std::unique_ptr<IDecompressor> Gz();
static std::unique_ptr<IDecompressor> Brotli();
static std::unique_ptr<IDecompressor> Lz4();
+ static std::unique_ptr<IDecompressor> Zstd();
static std::unique_ptr<IDecompressor> FromString(std::string_view compressor);
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
index 4c5a8bf..6749cf1 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp
@@ -30,6 +30,7 @@
#include <zlib.h>
#include "cow_decompress.h"
+#include "libsnapshot/cow_format.h"
namespace android {
namespace snapshot {
@@ -777,6 +778,11 @@
case kCowCompressBrotli:
decompressor = IDecompressor::Brotli();
break;
+ case kCowCompressZstd:
+ if (header_.block_size != op->data_length) {
+ decompressor = IDecompressor::Zstd();
+ }
+ break;
case kCowCompressLz4:
if (header_.block_size != op->data_length) {
decompressor = IDecompressor::Lz4();
diff --git a/fs_mgr/libsnapshot/snapuserd/Android.bp b/fs_mgr/libsnapshot/snapuserd/Android.bp
index 1e03683..9fe567a 100644
--- a/fs_mgr/libsnapshot/snapuserd/Android.bp
+++ b/fs_mgr/libsnapshot/snapuserd/Android.bp
@@ -112,6 +112,7 @@
"liblz4",
"libext4_utils",
"liburing",
+ "libzstd",
],
header_libs: [
diff --git a/init/Android.bp b/init/Android.bp
index 7b52903..41c7a95 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -169,6 +169,7 @@
"libfsverity_init",
"liblmkd_utils",
"liblz4",
+ "libzstd",
"libmini_keyctl_static",
"libmodprobe",
"libprocinfo",
@@ -370,6 +371,7 @@
"libprotobuf-cpp-lite",
"libsnapshot_cow",
"liblz4",
+ "libzstd",
"libsnapshot_init",
"update_metadata-protos",
"libprocinfo",