The crc32c code used in xfsprogs was copied directly from the Linux kernel. However, that code selects slice-by-4 by default, which isn't the fastest -- that's slice-by-8, which trades table size for speed. Fix some makefile dependency problems and explicitly select the algorithm we want. With this patch applied, I see about a 10% drop in CPU time running xfs_repair. Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> --- libxfs/Makefile | 4 ++-- libxfs/crc32defs.h | 3 +++ 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/libxfs/Makefile b/libxfs/Makefile index 0f3759e..c5dc382 100644 --- a/libxfs/Makefile +++ b/libxfs/Makefile @@ -124,7 +124,7 @@ LDIRT = gen_crc32table crc32table.h crc32selftest default: crc32selftest ltdepend $(LTLIBRARY) -crc32table.h: gen_crc32table.c +crc32table.h: gen_crc32table.c crc32defs.h @echo " [CC] gen_crc32table" $(Q) $(BUILD_CC) $(BUILD_CFLAGS) -o gen_crc32table $< @echo " [GENERATE] $@" @@ -135,7 +135,7 @@ crc32table.h: gen_crc32table.c # systems/architectures. Hence we make sure that xfsprogs will never use a # busted CRC calculation at build time and hence avoid putting bad CRCs down on # disk. -crc32selftest: gen_crc32table.c crc32table.h crc32.c +crc32selftest: gen_crc32table.c crc32table.h crc32.c crc32defs.h @echo " [TEST] CRC32" $(Q) $(BUILD_CC) $(BUILD_CFLAGS) -D CRC32_SELFTEST=1 crc32.c -o $@ $(Q) ./$@ diff --git a/libxfs/crc32defs.h b/libxfs/crc32defs.h index 64cba2c..153f44c 100644 --- a/libxfs/crc32defs.h +++ b/libxfs/crc32defs.h @@ -1,3 +1,6 @@ +/* Use slice-by-8, which is the fastest variant. */ +# define CRC_LE_BITS 64 + /* * There are multiple 16-bit CRC polynomials in common use, but this is * *the* standard CRC-32 polynomial, first popularized by Ethernet. -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
