Re: [PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2015-01-22 Thread Tim Chen
On Thu, 2015-01-22 at 12:05 +0800, Wanpeng Li wrote: > On Tue, Jan 20, 2015 at 07:18:37AM +0800, Wanpeng Li wrote: > >>> if (!rq->rd->overload) > >>> rq->rd->overload = true; > >> > >>Here 3882ec643997 ("nohz: Use IPI implicit full barrier against > >>rq->nr_running r/w"

Re: [PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2015-01-21 Thread Wanpeng Li
On Tue, Jan 20, 2015 at 07:18:37AM +0800, Wanpeng Li wrote: >>> if (!rq->rd->overload) >>> rq->rd->overload = true; >> >>Here 3882ec643997 ("nohz: Use IPI implicit full barrier against >>rq->nr_running r/w") might be a clue. >> >>Also, this is wrong, it breaks NOHZ_F

Re: [PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2015-01-19 Thread Wanpeng Li
On Mon, Jan 19, 2015 at 01:45:28PM +0100, Peter Zijlstra wrote: >On Wed, Nov 26, 2014 at 08:44:05AM +0800, Wanpeng Li wrote: >> The overload indicator is used for knowing when we can totally avoid load >> balancing to a cpu that is about to go idle. We can avoid load balancing >> when no cpu has cf

Re: [PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2015-01-19 Thread Wanpeng Li
On Mon, Jan 19, 2015 at 09:48:45AM -0800, Tim Chen wrote: >On Mon, 2015-01-19 at 13:45 +0100, Peter Zijlstra wrote: >> On Wed, Nov 26, 2014 at 08:44:05AM +0800, Wanpeng Li wrote: >> > The overload indicator is used for knowing when we can totally avoid load >> > balancing to a cpu that is about to

Re: [PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2015-01-19 Thread Tim Chen
On Mon, 2015-01-19 at 13:45 +0100, Peter Zijlstra wrote: > On Wed, Nov 26, 2014 at 08:44:05AM +0800, Wanpeng Li wrote: > > The overload indicator is used for knowing when we can totally avoid load > > balancing to a cpu that is about to go idle. We can avoid load balancing > > when no cpu has cfs t

Re: [PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2015-01-19 Thread Peter Zijlstra
On Wed, Nov 26, 2014 at 08:44:05AM +0800, Wanpeng Li wrote: > The overload indicator is used for knowing when we can totally avoid load > balancing to a cpu that is about to go idle. We can avoid load balancing > when no cpu has cfs task and both rt and deadline have push/pull mechanism > to do the

[PATCH v6 5/7] sched/fair: fix idle balance when remaining tasks are all non-CFS tasks

2014-11-25 Thread Wanpeng Li
The overload indicator is used for knowing when we can totally avoid load balancing to a cpu that is about to go idle. We can avoid load balancing when no cpu has cfs task and both rt and deadline have push/pull mechanism to do their own balancing. However, rq->nr_running on behalf of the total nu