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| author | Uros Bizjak <ubizjak@gmail.com> | 2022-07-08 16:07:36 +0200 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-07-17 17:14:47 -0700 |
| commit | 04ec006171badc73f749dc1cd9d66e05f8575a81 (patch) | |
| tree | de870dacd5654ddd7a5795a29ccf6de657a519d9 /.clang-format | |
| parent | dcadcf1c30619ead2f3280bfb7f74de8304be2bb (diff) | |
| download | linux-04ec006171badc73f749dc1cd9d66e05f8575a81.tar.gz | |
mm/page_alloc: use try_cmpxchg in set_pfnblock_flags_mask
Use try_cmpxchg instead of cmpxchg in set_pfnblock_flags_mask. x86
CMPXCHG instruction returns success in ZF flag, so this change saves a
compare after cmpxchg (and related move instruction in front of cmpxchg).
The main loop improves from:
1c5d: 48 89 c2 mov %rax,%rdx
1c60: 48 89 c1 mov %rax,%rcx
1c63: 48 21 fa and %rdi,%rdx
1c66: 4c 09 c2 or %r8,%rdx
1c69: f0 48 0f b1 16 lock cmpxchg %rdx,(%rsi)
1c6e: 48 39 c1 cmp %rax,%rcx
1c71: 75 ea jne 1c5d <...>
to:
1c60: 48 89 ca mov %rcx,%rdx
1c63: 48 21 c2 and %rax,%rdx
1c66: 4c 09 c2 or %r8,%rdx
1c69: f0 48 0f b1 16 lock cmpxchg %rdx,(%rsi)
1c6e: 75 f0 jne 1c60 <...>
Link: https://lkml.kernel.org/r/20220708140736.8737-1-ubizjak@gmail.com
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to '.clang-format')
0 files changed, 0 insertions, 0 deletions