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Revert "sched/fair: Fix fairness issue on migration" 

Mike reported that this recent commit:

  3a47d5124a ("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>
This commit is contained in:
Ingo Molnar 2016-05-11 08:25:53 +02:00
parent c5114626f3
commit 53d3bc773e
1 changed files with 7 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
kernel/sched/fair.c
View File

@ -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 run-time statistics of the 'current'.
*/
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.
*/
if (renorm && !curr)
se->vruntime += cfs_rq->min_vruntime;
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;