Messages in this thread Patch in this message |  | | | Subject | Re: hackbench regression with kernel 2.6.32-rc1 | | From | Mike Galbraith <> | | Date | Fri, 16 Oct 2009 13:06:32 +0200 |
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On Tue, 2009-10-13 at 11:12 +0800, Zhang, Yanmin wrote:
> NEXT_BUDDY has no help on volanoMark and tbench.
Can you try the patch below please? It does tries to preserve buddy affinity where possible, and mitigates over-preemption by strengthening buddies a bit. It improves vmark here by ~7%.
diff --git a/kernel/sched.c b/kernel/sched.c index 00f9e71..fb025d4 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2007,8 +2007,12 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) /* * Buddy candidates are cache hot: + * + * Do not honor buddies if there may be nothing else to + * prevent us from becoming idle. */ if (sched_feat(CACHE_HOT_BUDDY) && + task_rq(p)->nr_running >= sched_nr_latency && (&p->se == cfs_rq_of(&p->se)->next || &p->se == cfs_rq_of(&p->se)->last)) return 1; diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index c32c3e6..428bf55 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -863,18 +863,20 @@ static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) struct sched_entity *se = __pick_next_entity(cfs_rq); struct sched_entity *buddy; - if (cfs_rq->next) { + if (cfs_rq->next && sched_feat(NEXT_BUDDY)) { buddy = cfs_rq->next; - cfs_rq->next = NULL; - if (wakeup_preempt_entity(buddy, se) < 1) + if (wakeup_preempt_entity(buddy, se) < 1) { + cfs_rq->next = NULL; return buddy; + } } - if (cfs_rq->last) { + if (cfs_rq->last && sched_feat(LAST_BUDDY)) { buddy = cfs_rq->last; - cfs_rq->last = NULL; - if (wakeup_preempt_entity(buddy, se) < 1) + if (wakeup_preempt_entity(buddy, se) < 1) { + cfs_rq->last = NULL; return buddy; + } } return se; @@ -1600,9 +1602,9 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ * Also, during early boot the idle thread is in the fair class, for * obvious reasons its a bad idea to schedule back to the idle thread. */ - if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle)) + if (!(wake_flags & WF_FORK) && likely(se->on_rq && curr != rq->idle)) set_last_buddy(se); - if (sched_feat(NEXT_BUDDY) && !(wake_flags & WF_FORK)) + if (!(wake_flags & WF_FORK)) set_next_buddy(pse); /*
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