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| author |  Uros Bizjak <ubizjak@gmail.com>
| 2022-05-18 20:49:53 +0200 |
|---|---|---|
| committer |  Peter Zijlstra <peterz@infradead.org>
| 2022-05-19 23:46:09 +0200 |
| commit | 8491d1bdf5de152f27fc941e2dcdc4e66c950542 (patch) | |
| tree | c971126e067abf917f5204a5cd2ce87305240cae /kernel/sched/clock.c | |
| parent | locking/atomic/x86: Introduce arch_try_cmpxchg64 (diff) | |
| download | linux-8491d1bdf5de152f27fc941e2dcdc4e66c950542.tar.gz linux-8491d1bdf5de152f27fc941e2dcdc4e66c950542.tar.bz2 linux-8491d1bdf5de152f27fc941e2dcdc4e66c950542.zip | |
sched/clock: Use try_cmpxchg64 in sched_clock_{local,remote}
Use try_cmpxchg64 instead of cmpxchg64 (*ptr, old, new) != old in
sched_clock_{local,remote}. x86 cmpxchg returns success in ZF flag,
so this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220518184953.3446778-1-ubizjak@gmail.com
Diffstat (limited to 'kernel/sched/clock.c')
| -rw-r--r-- | kernel/sched/clock.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index d9272d9061a3..e374c0c923da 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -287,7 +287,7 @@ again: clock = wrap_max(clock, min_clock); clock = wrap_min(clock, max_clock); - if (cmpxchg64(&scd->clock, old_clock, clock) != old_clock) + if (!try_cmpxchg64(&scd->clock, &old_clock, clock)) goto again; return clock; @@ -349,7 +349,7 @@ again: val = remote_clock; } - if (cmpxchg64(ptr, old_val, val) != old_val) + if (!try_cmpxchg64(ptr, &old_val, val)) goto again; return val; |