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Date: Fri, 31 Aug 2018 17:07:21 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] sched/pelt: fix update_blocked_averages() for dl and
rt
On Fri, Aug 31, 2018 at 04:56:19PM +0200, Vincent Guittot wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 309c93f..bc1de21 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;
Can you do me a v3 where you move that rq->curr dereference under the
rq->lock?
I _think_ it is actually OK, but it is really dodgy. Moving it under
rq->lock makes it obvious correct.
> @@ -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))
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