From 53d3bc773eaa7ab1cf63585e76af7ee869d5e709 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 11 May 2016 08:25:53 +0200 Subject: [PATCH] Revert "sched/fair: Fix fairness issue on migration" Mike reported that this recent commit: 3a47d5124a95 ("sched/fair: Fix fairness issue on migration") ... broke interactivity and the signal starvation test. We have a proper fix series in the works but ran out of time for v4.6, so revert the commit. Reported-by: Mike Galbraith Acked-by: Peter Zijlstra Cc: Thomas Gleixner Cc: Linus Torvalds Cc: Peter Zijlstra Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 20 ++++++-------------- 1 file changed, 6 insertions(+), 14 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 40748dc8ea3e..e7dd0ec169be 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3188,25 +3188,17 @@ static inline void check_schedstat_required(void) static void enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { - bool renorm = !(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING); - bool curr = cfs_rq->curr == se; - /* - * If we're the current task, we must renormalise before calling - * update_curr(). + * Update the normalized vruntime before updating min_vruntime + * through calling update_curr(). */ - if (renorm && curr) + if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING)) se->vruntime += cfs_rq->min_vruntime; - update_curr(cfs_rq); - /* - * Otherwise, renormalise after, such that we're placed at the current - * moment in time, instead of some random moment in the past. + * Update run-time statistics of the 'current'. */ - if (renorm && !curr) - se->vruntime += cfs_rq->min_vruntime; - + update_curr(cfs_rq); enqueue_entity_load_avg(cfs_rq, se); account_entity_enqueue(cfs_rq, se); update_cfs_shares(cfs_rq); @@ -3222,7 +3214,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) update_stats_enqueue(cfs_rq, se); check_spread(cfs_rq, se); } - if (!curr) + if (se != cfs_rq->curr) __enqueue_entity(cfs_rq, se); se->on_rq = 1; -- 2.39.2