From a7558e01056f5191ff2ecff53b075dcb9e484188 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 14 Sep 2009 20:02:34 +0200 Subject: [PATCH] sched: Add WF_FORK Avoid the cache buddies from biasing the time distribution away from fork()ers. Normally the next buddy will be the preferred scheduling target, but this makes fork()s prefer to run the new child, whereas we prefer to run the parent, since that will generate more work. Signed-off-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- include/linux/sched.h | 1 + kernel/sched.c | 2 +- kernel/sched_fair.c | 2 +- 3 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index 3b07168b6f0..ee1f8899309 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1028,6 +1028,7 @@ struct sched_domain; * wake flags */ #define WF_SYNC 0x01 /* waker goes to sleep after wakup */ +#define WF_FORK 0x02 /* child wakeup after fork */ struct sched_class { const struct sched_class *next; diff --git a/kernel/sched.c b/kernel/sched.c index 4da335cec8e..0d4c4fea331 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2602,7 +2602,7 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags) inc_nr_running(rq); } trace_sched_wakeup_new(rq, p, 1); - check_preempt_curr(rq, p, 0); + check_preempt_curr(rq, p, WF_FORK); #ifdef CONFIG_SMP if (p->sched_class->task_wake_up) p->sched_class->task_wake_up(rq, p); diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index 007958e3c93..6766959c7f4 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1580,7 +1580,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int flags */ if (sched_feat(LAST_BUDDY) && likely(se->on_rq && curr != rq->idle)) set_last_buddy(se); - if (sched_feat(NEXT_BUDDY)) + if (sched_feat(NEXT_BUDDY) && !(flags & WF_FORK)) set_next_buddy(pse); /*