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| author | mav <mav@FreeBSD.org> | 2014-09-14 22:13:19 +0000 |
|---|---|---|
| committer | mav <mav@FreeBSD.org> | 2014-09-14 22:13:19 +0000 |
| commit | 1cfaa7d62ba4ad88a87e3d3c7d9b1c7fc51059a0 (patch) | |
| tree | cb7a2bdd13fd7cc0cd6fd16bce82d4b95a22a7c5 /sys/kern | |
| parent | 80ccb248ca5a4784c12f1eb4893ff05034603733 (diff) | |
| download | FreeBSD-src-1cfaa7d62ba4ad88a87e3d3c7d9b1c7fc51059a0.zip FreeBSD-src-1cfaa7d62ba4ad88a87e3d3c7d9b1c7fc51059a0.tar.gz | |
Add couple memory barries to serialize tdq_cpu_idle and tdq_load accesses.
This change fixes transient performance drops in some of my benchmarks,
vanishing as soon as I am trying to collect any stats from the scheduler.
It looks like reordered access to those variables sometimes caused loss of
IPI_PREEMPT, that delayed thread execution until some later interrupt.
MFC after: 3 days
Diffstat (limited to 'sys/kern')
| -rw-r--r-- | sys/kern/sched_ule.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c index 0a63c01..7fe902e 100644 --- a/sys/kern/sched_ule.c +++ b/sys/kern/sched_ule.c @@ -1037,6 +1037,7 @@ tdq_notify(struct tdq *tdq, struct thread *td) ctd = pcpu_find(cpu)->pc_curthread; if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) return; + mb(); if (TD_IS_IDLETHREAD(ctd)) { /* * If the MD code has an idle wakeup routine try that before @@ -2640,6 +2641,7 @@ sched_idletd(void *dummy) /* Run main MD idle handler. */ tdq->tdq_cpu_idle = 1; + mb(); cpu_idle(switchcnt * 4 > sched_idlespinthresh); tdq->tdq_cpu_idle = 0; |
