From: Mike Galbraith Date: Wed, 28 Jan 2009 13:51:39 +0000 (+0100) Subject: sched: clear buddies more aggressively X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=a9f3e2b549f83a9cdab873abf4140be27c05a3f2;p=linux-2.6-omap-h63xx.git sched: clear buddies more aggressively It was noticed that a task could get re-elected past its run quota due to buddy affinities. This could increase latency a little. Cure it by more aggresively clearing buddy state. We do so in two situations: - when we force preempt - when we select a buddy to run Signed-off-by: Mike Galbraith Signed-off-by: Peter Zijlstra Signed-off-by: Ingo Molnar --- diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index fdc41750468..75248b9ff4c 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -768,8 +768,14 @@ check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr) ideal_runtime = sched_slice(cfs_rq, curr); delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime; - if (delta_exec > ideal_runtime) + if (delta_exec > ideal_runtime) { resched_task(rq_of(cfs_rq)->curr); + /* + * The current task ran long enough, ensure it doesn't get + * re-elected due to buddy favours. + */ + clear_buddies(cfs_rq, curr); + } } static void @@ -1445,6 +1451,11 @@ static struct task_struct *pick_next_task_fair(struct rq *rq) do { se = pick_next_entity(cfs_rq); + /* + * If se was a buddy, clear it so that it will have to earn + * the favour again. + */ + clear_buddies(cfs_rq, se); set_next_entity(cfs_rq, se); cfs_rq = group_cfs_rq(se); } while (cfs_rq);