44 lines
1.8 KiB
Diff
44 lines
1.8 KiB
Diff
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From: Matthias Schiffer <mschiffer@universe-factory.net>
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Date: Wed, 13 May 2020 20:33:46 +0200
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Subject: build: compress kernel debuginfo using zstd
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zstd with its default settings (compression level -3) compresses better
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than bzip2 -9 (which is the default setting), and is an order of magnitude
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faster.
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I made the following measurements for the most common compression tools
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(all standard Debian Buster versions, default flags unless noted
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otherwise), using the debug information of a large x86-64 kernel with
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ALL_KMODS:
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* kernel-debug.tar: 376M
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* kernel-debug.tar.gz: 101M, compressed in ~12s
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* kernel-debug.tar.bz2: 91M, compressed in ~15s
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* kernel-debug.tar.xz: 57M, compressed in ~101s
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* kernel-debug.tar.zst: 86M, compressed in ~1s
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With zstd, there is still some room for improvement by increasing the
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compression, but the slight increase in compression ratio
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(22.83% -> 19.46%) does not justify the significant increase in
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compression time (about 5 times on my machine) in my opinion.
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Note that multithreaded compression (-T argument) does not affect
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reproducibility with zstd.
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Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
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(cherry picked from commit 4bd7990488b0ca7b5cae16f0a9147a4146759053)
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diff --git a/include/kernel-build.mk b/include/kernel-build.mk
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index 3fdf7efc52857a5184348cc1261848f75751b8a9..af7c3a8f0bb15c7e0d7072876705ff0bf4f9c8d1 100644
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--- a/include/kernel-build.mk
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+++ b/include/kernel-build.mk
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@@ -70,7 +70,7 @@ ifdef CONFIG_COLLECT_KERNEL_DEBUG
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$(FIND) $(KERNEL_BUILD_DIR)/debug -type f | $(XARGS) $(KERNEL_CROSS)strip --only-keep-debug
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$(TAR) c -C $(KERNEL_BUILD_DIR) debug \
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$(if $(SOURCE_DATE_EPOCH),--mtime="@$(SOURCE_DATE_EPOCH)") \
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- | bzip2 -c -9 > $(BIN_DIR)/kernel-debug.tar.bz2
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+ | zstd -T0 -f -o $(BIN_DIR)/kernel-debug.tar.zst
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endef
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endif
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