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From: Patrick Bellasi <patrick.bellasi@arm.com>
To: Suren Baghdasaryan <surenb@google.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>, Tejun Heo <tj@kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Paul Turner <pjt@google.com>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@google.com>,
	Joel Fernandes <joelaf@google.com>,
	Steve Muckle <smuckle@google.com>
Subject: Re: [PATCH v2 07/12] sched/core: uclamp: enforce last task UCLAMP_MAX
Date: Mon, 23 Jul 2018 16:02:49 +0100
Message-ID: <20180723150249.GD2683@e110439-lin> (raw)
In-Reply-To: <CAJuCfpH6CsDVG35Z3NV87mUgJW9TmoCuOs8GeW2TEqkP0K0f9g@mail.gmail.com>

On 20-Jul 18:23, Suren Baghdasaryan wrote:
> Hi Patrick,

Hi Sure,
thank!

> On Mon, Jul 16, 2018 at 1:29 AM, Patrick Bellasi
> <patrick.bellasi@arm.com> wrote:

[...]

> > @@ -977,13 +991,21 @@ static inline void uclamp_cpu_get_id(struct task_struct *p,
> >         uc_grp = &rq->uclamp.group[clamp_id][0];
> >         uc_grp[group_id].tasks += 1;
> >
> > +       /* Force clamp update on idle exit */
> > +       uc_cpu = &rq->uclamp;
> > +       clamp_value = p->uclamp[clamp_id].value;
> > +       if (unlikely(uc_cpu->flags & UCLAMP_FLAG_IDLE)) {
> 
> The condition below is not needed because UCLAMP_FLAG_IDLE is set only
> for UCLAMP_MAX clamp_id, therefore the above condition already covers
> the one below.

Not really, this function is called two times, the first time to
update UCLAMP_MIN and a second time to update UCLAMP_MAX.

For both clamp_id we want to force update uc_cpu->value[clamp_id],
thus the UCLAMP_FLAG_IDLE flag has to be cleared only the second time.

Maybe I can had the following comment to better explain the reason of
the check:

		/*
		 * This function is called for both UCLAMP_MIN (before) and
		 * UCLAMP_MAX (after). Let's reset the flag only the when
		 * we know that UCLAMP_MIN has been already updated.
		 */

> > +               if (clamp_id == UCLAMP_MAX)
> > +                       uc_cpu->flags &= ~UCLAMP_FLAG_IDLE;
> > +               uc_cpu->value[clamp_id] = clamp_value;
> > +               return;
> > +       }

[...]

-- 
#include <best/regards.h>

Patrick Bellasi

  reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-16  8:28 [PATCH v2 00/12] Add utilization clamping support Patrick Bellasi
2018-07-16  8:28 ` [PATCH v2 01/12] sched/core: uclamp: extend sched_setattr to support utilization clamping Patrick Bellasi
2018-07-17 17:50   ` Joel Fernandes
2018-07-18  8:42     ` Patrick Bellasi
2018-07-18 17:02       ` Joel Fernandes
2018-07-17 18:04   ` Joel Fernandes
2018-07-16  8:28 ` [PATCH v2 02/12] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups Patrick Bellasi
2018-07-19 23:51   ` Suren Baghdasaryan
2018-07-20 15:11     ` Patrick Bellasi
2018-07-21  0:25       ` Suren Baghdasaryan
2018-07-23 13:36         ` Patrick Bellasi
2018-07-16  8:28 ` [PATCH v2 03/12] sched/core: uclamp: add CPU's clamp groups accounting Patrick Bellasi
2018-07-20 20:25   ` Suren Baghdasaryan
2018-07-16  8:28 ` [PATCH v2 04/12] sched/core: uclamp: update CPU's refcount on clamp changes Patrick Bellasi
2018-07-16  8:28 ` [PATCH v2 05/12] sched/cpufreq: uclamp: add utilization clamping for FAIR tasks Patrick Bellasi
2018-07-16  8:29 ` [PATCH v2 06/12] sched/cpufreq: uclamp: add utilization clamping for RT tasks Patrick Bellasi
2018-07-16  8:29 ` [PATCH v2 07/12] sched/core: uclamp: enforce last task UCLAMP_MAX Patrick Bellasi
2018-07-21  1:23   ` Suren Baghdasaryan
2018-07-23 15:02     ` Patrick Bellasi [this message]
2018-07-23 16:40       ` Suren Baghdasaryan
2018-07-16  8:29 ` [PATCH v2 08/12] sched/core: uclamp: extend cpu's cgroup controller Patrick Bellasi
2018-07-21  2:37   ` Suren Baghdasaryan
2018-07-21  3:16     ` Suren Baghdasaryan
2018-07-23 15:17     ` Patrick Bellasi
2018-07-23 15:30   ` Tejun Heo
2018-07-23 17:22     ` Patrick Bellasi
2018-07-24 13:29       ` Tejun Heo
2018-07-24 15:39         ` Patrick Bellasi
2018-07-27  0:39         ` Joel Fernandes
2018-07-27  8:09           ` Quentin Perret
2018-07-16  8:29 ` [PATCH v2 09/12] sched/core: uclamp: map TG's clamp values into CPU's clamp groups Patrick Bellasi
2018-07-16  8:29 ` [PATCH v2 10/12] sched/core: uclamp: use TG's clamps to restrict Task's clamps Patrick Bellasi
2018-07-22  3:05   ` Suren Baghdasaryan
2018-07-23 15:40     ` Patrick Bellasi
2018-07-23 17:11       ` Suren Baghdasaryan
2018-07-24  9:56         ` Patrick Bellasi
2018-07-24 15:28           ` Suren Baghdasaryan
2018-07-24 15:49             ` Patrick Bellasi
2018-07-16  8:29 ` [PATCH v2 11/12] sched/core: uclamp: update CPU's refcount on TG's clamp changes Patrick Bellasi
2018-07-22  3:17   ` Suren Baghdasaryan
2018-07-16  8:29 ` [PATCH v2 12/12] sched/core: uclamp: use percentage clamp values Patrick Bellasi
2018-07-22  4:04   ` Suren Baghdasaryan
2018-07-24 16:43     ` Patrick Bellasi
2018-07-24 17:11       ` Suren Baghdasaryan
2018-07-24 17:17         ` Patrick Bellasi
2018-07-17 13:03 ` [PATCH v2 00/12] Add utilization clamping support Joel Fernandes
2018-07-17 13:41   ` Patrick Bellasi

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