Messages in this thread Patch in this message | | | Subject | Re: PostgreSQL pgbench performance regression in 2.6.23+ | From | Mike Galbraith <> | Date | Sat, 24 May 2008 10:08:30 +0200 |
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On Sat, 2008-05-24 at 01:46 +0200, Mike Galbraith wrote: > On Fri, 2008-05-23 at 19:18 -0400, Greg Smith wrote:
> > Should I still be trying Peter's se.waker patch as well in this mix > > somewhere? > > Yeah.
btw, the problem with 2.6.25.4 and this load is one and the same. With a 1:N load, you really don't want work generator waking all worker-bees on it's CPU. The patchlet below let's you turn it off.
diff --git a/kernel/sched.c b/kernel/sched.c index 1e4596c..5641eb8 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -596,6 +596,7 @@ enum { SCHED_FEAT_START_DEBIT = 4, SCHED_FEAT_HRTICK = 8, SCHED_FEAT_DOUBLE_TICK = 16, + SCHED_FEAT_SYNC_WAKEUPS = 32, }; const_debug unsigned int sysctl_sched_features = @@ -603,7 +604,8 @@ const_debug unsigned int sysctl_sched_features = SCHED_FEAT_WAKEUP_PREEMPT * 1 | SCHED_FEAT_START_DEBIT * 1 | SCHED_FEAT_HRTICK * 1 | - SCHED_FEAT_DOUBLE_TICK * 0; + SCHED_FEAT_DOUBLE_TICK * 0 | + SCHED_FEAT_SYNC_WAKEUPS * 0; #define sched_feat(x) (sysctl_sched_features & SCHED_FEAT_##x) @@ -1902,6 +1904,9 @@ static int try_to_wake_up(struct task_struct *p, unsigned int state, int sync) long old_state; struct rq *rq; + if (!sched_feat(SYNC_WAKEUPS)) + sync = 0; + smp_wmb(); rq = task_rq_lock(p, &flags); old_state = p->state;
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