Use try_cmpxchg instead of cmpxchg (*ptr, old, new) == old
in task_numa_work. x86 CMPXCHG instruction returns success in ZF flag,
so this change saves a compare after cmpxchg (and related move
instruction in front of cmpxchg).
No functional change intended.
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Juri Lelli <[email protected]>
Cc: Vincent Guittot <[email protected]>
Signed-off-by: Uros Bizjak <[email protected]>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 914096c5b1ae..efe73ee89989 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2802,7 +2802,7 @@ static void task_numa_work(struct callback_head *work)
}
next_scan = now + msecs_to_jiffies(p->numa_scan_period);
- if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
+ if (!try_cmpxchg(&mm->numa_next_scan, &migrate, next_scan))
return;
/*
--
2.37.1