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| author | Uros Bizjak <ubizjak@gmail.com> | 2024-10-01 14:45:57 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-10-25 11:01:50 +0300 |
| commit | 0d75e0c420e52b4057a2de274054a5274209a2ae (patch) | |
| tree | 62a22db7cd0ec18bc0a0e4dc135f498001ac7ed3 /tools/perf/scripts/python/export-to-postgresql.py | |
| parent | f730fd535fc51573f982fad629f2fc6b4a0cde2f (diff) | |
| download | linux-0d75e0c420e52b4057a2de274054a5274209a2ae.tar.xz | |
locking/osq_lock: Use atomic_try_cmpxchg_release() in osq_unlock()
Replace this pattern in osq_unlock():
atomic_cmpxchg(*ptr, old, new) == old
... with the simpler and faster:
atomic_try_cmpxchg(*ptr, &old, new)
The x86 CMPXCHG instruction returns success in the ZF flag,
so this change saves a compare after the CMPXCHG. The code
in the fast path of osq_unlock() improves from:
11b: 31 c9 xor %ecx,%ecx
11d: 8d 50 01 lea 0x1(%rax),%edx
120: 89 d0 mov %edx,%eax
122: f0 0f b1 0f lock cmpxchg %ecx,(%rdi)
126: 39 c2 cmp %eax,%edx
128: 75 05 jne 12f <...>
to:
12b: 31 d2 xor %edx,%edx
12d: 83 c0 01 add $0x1,%eax
130: f0 0f b1 17 lock cmpxchg %edx,(%rdi)
134: 75 05 jne 13b <...>
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/r/20241001114606.820277-1-ubizjak@gmail.com
Diffstat (limited to 'tools/perf/scripts/python/export-to-postgresql.py')
0 files changed, 0 insertions, 0 deletions