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| author | Nick Terrell <terrelln@fb.com> | 2020-08-14 17:30:10 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-14 19:56:56 -0700 |
| commit | b1a3e75e466d96383508634f3d2e477ac45f2fc1 (patch) | |
| tree | 2ee68329a75153499aa73de96cab7233d75733ee /lib/lz4/lz4hc_compress.c | |
| parent | a8a4b7aeaf841311cb13ff0f6c4710c7a00e68d4 (diff) | |
| download | linux-b1a3e75e466d96383508634f3d2e477ac45f2fc1.tar.gz linux-b1a3e75e466d96383508634f3d2e477ac45f2fc1.tar.xz | |
lz4: fix kernel decompression speed
This patch replaces all memcpy() calls with LZ4_memcpy() which calls
__builtin_memcpy() so the compiler can inline it.
LZ4 relies heavily on memcpy() with a constant size being inlined. In x86
and i386 pre-boot environments memcpy() cannot be inlined because memcpy()
doesn't get defined as __builtin_memcpy().
An equivalent patch has been applied upstream so that the next import
won't lose this change [1].
I've measured the kernel decompression speed using QEMU before and after
this patch for the x86_64 and i386 architectures. The speed-up is about
10x as shown below.
Code Arch Kernel Size Time Speed
v5.8 x86_64 11504832 B 148 ms 79 MB/s
patch x86_64 11503872 B 13 ms 885 MB/s
v5.8 i386 9621216 B 91 ms 106 MB/s
patch i386 9620224 B 10 ms 962 MB/s
I also measured the time to decompress the initramfs on x86_64, i386, and
arm. All three show the same decompression speed before and after, as
expected.
[1] https://github.com/lz4/lz4/pull/890
Signed-off-by: Nick Terrell <terrelln@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Yann Collet <yann.collet.73@gmail.com>
Cc: Gao Xiang <gaoxiang25@huawei.com>
Cc: Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Link: http://lkml.kernel.org/r/20200803194022.2966806-1-nickrterrell@gmail.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'lib/lz4/lz4hc_compress.c')
| -rw-r--r-- | lib/lz4/lz4hc_compress.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/lz4/lz4hc_compress.c b/lib/lz4/lz4hc_compress.c index 1b61d874e337..e7ac8694b797 100644 --- a/lib/lz4/lz4hc_compress.c +++ b/lib/lz4/lz4hc_compress.c @@ -570,7 +570,7 @@ _Search3: *op++ = (BYTE) lastRun; } else *op++ = (BYTE)(lastRun<<ML_BITS); - memcpy(op, anchor, iend - anchor); + LZ4_memcpy(op, anchor, iend - anchor); op += iend - anchor; } |