| Message ID | 2d9ce4d894da492ed79b6a2d3ba51d6e859e81a2.1589716209.git.mschiffer@universe-factory.net |
|---|---|
| State | Accepted |
| Delegated to: | Matthias Schiffer |
| Headers | show |
| Series | Switch to zstd for kernel debuginfo compression | expand |
diff --git a/include/kernel-build.mk b/include/kernel-build.mk index c371e78ab9b0..32c91a5b8359 100644 --- a/include/kernel-build.mk +++ b/include/kernel-build.mk @@ -70,7 +70,7 @@ ifdef CONFIG_COLLECT_KERNEL_DEBUG $(FIND) $(KERNEL_BUILD_DIR)/debug -type f | $(XARGS) $(KERNEL_CROSS)strip --only-keep-debug $(TAR) c -C $(KERNEL_BUILD_DIR) debug \ $(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \ - | bzip2 -c -9 > $(BIN_DIR)/kernel-debug.tar.bz2 + | zstd -T0 -f -o $(BIN_DIR)/kernel-debug.tar.zst endef endif
zstd with its default settings (compression level -3) compresses better than bzip2 -9 (which is the default setting), and is an order of magnitude faster. I made the following measurements for the most common compression tools (all standard Debian Buster versions, default flags unless noted otherwise), using the debug information of a large x86-64 kernel with ALL_KMODS: * kernel-debug.tar: 376M * kernel-debug.tar.gz: 101M, compressed in ~12s * kernel-debug.tar.bz2: 91M, compressed in ~15s * kernel-debug.tar.xz: 57M, compressed in ~101s * kernel-debug.tar.zst: 86M, compressed in ~1s With zstd, there is still some room for improvement by increasing the compression, but the slight increase in compression ratio (22.83% -> 19.46%) does not justify the significant increase in compression time (about 5 times on my machine) in my opinion. Note that multithreaded compression (-T argument) does not affect reproducibility with zstd. Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net> --- include/kernel-build.mk | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)