Messages in this thread | | | Subject | Re: [patch] sched: call resched_task() conditionally from new task wake up path. | From | Peter Zijlstra <> | Date | Thu, 28 Aug 2008 11:25:07 +0200 |
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On Thu, 2008-08-28 at 14:42 +0530, Bharata B Rao wrote: > Hi, > > sched: call resched_task() conditionally from new task wake up path. > > - During wake up of a new task, task_new_fair() can do a resched_task() > on the current task. Later in the code path, check_preempt_curr() also ends > up doing the same, which can be avoided. Check if TIF_NEED_RESCHED is > already set for the current task. > > - task_new_fair() does a resched_task() on the current task unconditionally. > This can be done only in case when child runs before the parent. > > Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com> > CC: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> CC: Ingo Molnar <mingo@elte.hu> > --- > kernel/sched_fair.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -1348,6 +1348,13 @@ static void check_preempt_wakeup(struct > if (unlikely(se == pse)) > return; > > + /* > + * We can come here with TIF_NEED_RESCHED already set from new task > + * wake up path. > + */ > + if (test_tsk_need_resched(curr)) > + return; > + > cfs_rq_of(pse)->next = pse; > > /* > @@ -1615,10 +1622,10 @@ static void task_new_fair(struct rq *rq, > * 'current' within the tree based on its new key value. > */ > swap(curr->vruntime, se->vruntime); > + resched_task(rq->curr); > } > > enqueue_task_fair(rq, p, 0); > - resched_task(rq->curr); > } > > /* > > Regards, > Bharata.
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