Messages in this thread | | | From | Vincent Guittot <> | Date | Fri, 31 Aug 2018 16:45:13 +0200 | Subject | Re: [PATCH] sched/pelt: fix update_blocked_averages() for dl and rt |
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On Fri, 31 Aug 2018 at 16:41, Peter Zijlstra <peterz@infradead.org> wrote: > > On Fri, Aug 31, 2018 at 03:58:28PM +0200, Vincent Guittot wrote: > > update_blocked_averages() is called to periodiccally decay the stalled load > > of idle CPUs and to sync all loads before running load balance. > > > > When cfs rq is idle, it trigs a load balance during pick_next_task_fair() > > in order to potentially pull tasks and to use this newly idle CPU. This > > load balance happens whereas prev task from another class has not been put > > and its utilization updated yet. This may lead to wrongly account running > > time as idle time for rt or dl classes. > > > > Test that no rt or dl task is running when updating their utilization in > > update_blocked_averages(). > > > > We still update rt and dl utilization instead of simply skipping them to > > make sure that all metrics are synced when used during load balance. > > > > Fixes: 371bf4273269 ("sched/rt: Add rt_rq utilization tracking") > Fixes: 3727e0e16340 ("sched/dl: Add dl_rq utilization tracking") > > Right?
Yes
> > > Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> > > --- > > kernel/sched/fair.c | 5 +++-- > > 1 file changed, 3 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 309c93f..a1babaf 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -7262,6 +7262,7 @@ static void update_blocked_averages(int cpu) > > { > > struct rq *rq = cpu_rq(cpu); > > struct cfs_rq *cfs_rq, *pos; > > + const struct sched_class *curr_class = rq->curr->sched_class; > > struct rq_flags rf; > > bool done = true; > > > > @@ -7298,8 +7299,8 @@ static void update_blocked_averages(int cpu) > > if (cfs_rq_has_blocked(cfs_rq)) > > done = false; > > } > > - update_rt_rq_load_avg(rq_clock_task(rq), rq, 0); > > - update_dl_rq_load_avg(rq_clock_task(rq), rq, 0); > > + update_rt_rq_load_avg(rq_clock_task(rq), rq, curr_class == &rt_sched_class); > > + update_dl_rq_load_avg(rq_clock_task(rq), rq, curr_class == &dl_sched_class); > > update_irq_load_avg(rq, 0); > > /* Don't need periodic decay once load/util_avg are null */ > > if (others_have_blocked(rq)) > > Did you forget to update the second implementation of > update_blocked_averages() ?
Yes. I have sent this version to quickly. I'm going to send an update
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