From d95f412200652694e63e64bfd49f0ae274a54479 Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Tue, 1 Feb 2011 09:50:51 -0500 Subject: sched: Add yield_to(task, preempt) functionality Currently only implemented for fair class tasks. Add a yield_to_task method() to the fair scheduling class. allowing the caller of yield_to() to accelerate another thread in it's thread group, task group. Implemented via a scheduler hint, using cfs_rq->next to encourage the target being selected. We can rely on pick_next_entity to keep things fair, so noone can accelerate a thread that has already used its fair share of CPU time. This also means callers should only call yield_to when they really mean it. Calling it too often can result in the scheduler just ignoring the hint. Signed-off-by: Rik van Riel Signed-off-by: Marcelo Tosatti Signed-off-by: Mike Galbraith Signed-off-by: Peter Zijlstra LKML-Reference: <20110201095051.4ddb7738@annuminas.surriel.com> Signed-off-by: Ingo Molnar --- kernel/sched_fair.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'kernel/sched_fair.c') diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index c0fbeb992833..027024694043 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -1975,6 +1975,25 @@ static void yield_task_fair(struct rq *rq) set_skip_buddy(se); } +static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) +{ + struct sched_entity *se = &p->se; + + if (!se->on_rq) + return false; + + /* Tell the scheduler that we'd really like pse to run next. */ + set_next_buddy(se); + + /* Make p's CPU reschedule; pick_next_entity takes care of fairness. */ + if (preempt) + resched_task(rq->curr); + + yield_task_fair(rq); + + return true; +} + #ifdef CONFIG_SMP /************************************************** * Fair scheduling class load-balancing methods: @@ -4243,6 +4262,7 @@ static const struct sched_class fair_sched_class = { .enqueue_task = enqueue_task_fair, .dequeue_task = dequeue_task_fair, .yield_task = yield_task_fair, + .yield_to_task = yield_to_task_fair, .check_preempt_curr = check_preempt_wakeup, -- cgit v1.2.3