Messages in this thread |  | | Subject | Re: [v4.8-rc1 Regression] sched/fair: Apply more PELT fixes | From | Joseph Salisbury <> | Date | Fri, 14 Oct 2016 12:04:02 -0400 |
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On 10/14/2016 11:18 AM, Vincent Guittot wrote: > Le Friday 14 Oct 2016 à 14:10:07 (+0100), Dietmar Eggemann a écrit : >> On 14/10/16 09:24, Vincent Guittot wrote: >>> On 13 October 2016 at 23:34, Vincent Guittot <vincent.guittot@linaro.org> wrote: >>>> On 13 October 2016 at 20:49, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote: >>>>> On 13/10/16 17:48, Vincent Guittot wrote: >>>>>> On 13 October 2016 at 17:52, Joseph Salisbury >>>>>> <joseph.salisbury@canonical.com> wrote: >>>>>>> On 10/13/2016 06:58 AM, Vincent Guittot wrote: >>>>>>>> Hi, >>>>>>>> >>>>>>>> On 12 October 2016 at 18:21, Joseph Salisbury >>>>>>>> <joseph.salisbury@canonical.com> wrote: >>>>>>>>> On 10/12/2016 08:20 AM, Vincent Guittot wrote: >>>>>>>>>> On 8 October 2016 at 13:49, Mike Galbraith <efault@gmx.de> wrote: >>>>>>>>>>> On Sat, 2016-10-08 at 13:37 +0200, Vincent Guittot wrote: >>>>>>>>>>>> On 8 October 2016 at 10:39, Ingo Molnar <mingo@kernel.org> wrote: >>>>>>>>>>>>> * Peter Zijlstra <peterz@infradead.org> wrote: >>>>>>>>>>>>> >>>>>>>>>>>>>> On Fri, Oct 07, 2016 at 03:38:23PM -0400, Joseph Salisbury wrote: >> [...] >> >>>>> When I create a tg_root/tg_x/tg_y_1 and a tg_root/tg_x/tg_y_2 group, the tg_x->load_avg >>>>> becomes > 6*1024 before any tasks ran in it. >>>> This is normal as se->avg.load_avg is initialized to >>>> scale_load_down(se->load.weight) and this se->avg.load_avg will be >>>> added to tg_x[cpu]->cfs_rq->avg.load_avg when attached to the cfs_rq >> Yeah, you right, even when I've created 50 second level groups, >> tg_x->load_avg is ~6800. >> >> Could it have something to do with the fact that .se->load.weight = 2 >> for all these task groups? on a 64bit system? > I don't think so, the problem really comes from tg->load_avg = 381697 > but sum of cfs_rq[cpu]->tg_load_avg_contrib = 1013 which is << tg->load_avg > and cfs_rq[cpu]->tg_load_avg_contrib == cfs_rq[cpu]->avg.load_avg so we can't > expect any negative delta to remove this large value > >> In case we call __update_load_avg(..., se->on_rq * >> scale_load_down(se->load.weight), ...) we pass a weight argument of 0 >> for these se's. >> >> Does not happen with: >> >> - if (shares < MIN_SHARES) >> - shares = MIN_SHARES; >> + if (shares < scale_load(MIN_SHARES)) >> + shares = scale_load(MIN_SHARES); >> >> in calc_cfs_shares(). >> >> [...] >> >> Adding Omer to CC list, as he is able to reproduce this bug.
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