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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 02/12] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups
Date: Mon, 23 Jul 2018 14:36:15 +0100
Message-ID: <20180723133615.GB2683@e110439-lin> (raw)
In-Reply-To: <CAJuCfpGvpX5U9rED+vX=wW624GLZo8f=-2kOLGrY1UJSEXRh6g@mail.gmail.com>

On 20-Jul 17:25, Suren Baghdasaryan wrote:

[...]

> > ---8<---
> >
> > /* Uclamp flags */
> > #define SCHED_FLAG_UTIL_CLAMP_STRICT    0x11 /* Roll-back on failure */
> > #define SCHED_FLAG_UTIL_CLAMP_MIN       0x12 /* Update util_min */
> > #define SCHED_FLAG_UTIL_CLAMP_MAX       0x14 /* Update util_max */
> > #define SCHED_FLAG_UTIL_CLAMP           ( \
> >                 SCHED_FLAG_UTIL_CLAMP_MIN | SCHED_FLAG_UTIL_CLAMP_MAX)
> >
> 
> Having ability to update only min or only max this way might be indeed
> very useful.
> Instead of rolling back on failure I would suggest to check both
> inputs first to make sure there won't be any error before updating.
> This would remove the need for SCHED_FLAG_UTIL_CLAMP_STRICT (which I
> think any user would want to set to 1 anyway).
> Looks like uclamp_group_get() can fail only if uclamp_group_find()
> fails to find a slot for uclamp_value or a free slot. So one way to do
> this search before update is to call uclamp_group_find() for both
> UCLAMP_MIN and UCLAMP_MAX beforehand and if they succeed then pass
> obtained next_group_ids into uclamp_group_get() to avoid doing the
> same search twice. This requires some refactoring of
> uclamp_group_get() but I think the end result would be a cleaner and
> more predictable solution.

Yes, that sound possible... provided we check all the groups under the
same uclamp_mutex, it should be possible to find the group_ids before
actually increasing the refcount.

... will look into this for the next reposting.

-- 
#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 [this message]
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
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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