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authorIngo Molnar <mingo@kernel.org>2016-05-11 08:25:53 +0200
committerIngo Molnar <mingo@kernel.org>2016-05-11 08:25:53 +0200
commit53d3bc773eaa7ab1cf63585e76af7ee869d5e709 (patch)
treedb53cf2c46e8a052f624889ff8283d0495280b85
parentc5114626f33b62fa7595e57d87f33d9d1f8298a2 (diff)
downloadleg-kernel-53d3bc773eaa7ab1cf63585e76af7ee869d5e709.tar.gz
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 <efault@gmx.de> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
-rw-r--r--kernel/sched/fair.c20
1 files 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;