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From: Peter Zijlstra <peterz@infradead.org>
To: Patrick Bellasi <patrick.bellasi@arm.com>
Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
	linux-api@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	Tejun Heo <tj@kernel.org>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Paul Turner <pjt@google.com>,
	Quentin Perret <quentin.perret@arm.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>,
	Suren Baghdasaryan <surenb@google.com>
Subject: Re: [PATCH v6 05/16] sched/core: uclamp: Update CPU's refcount on clamp changes
Date: Tue, 22 Jan 2019 14:28:17 +0100	[thread overview]
Message-ID: <20190122132817.GG13777@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20190122104305.6vjx37muqsxm536t@e110439-lin>

On Tue, Jan 22, 2019 at 10:43:05AM +0000, Patrick Bellasi wrote:
> On 22-Jan 10:37, Peter Zijlstra wrote:

> > Sure, I get that. What I don't get is why you're adding that (2) here.
> > Like said, __sched_setscheduler() already does a dequeue/enqueue under
> > rq->lock, which should already take care of that.
> 
> Oh, ok... got it what you mean now.
> 
> With:
> 
>    [PATCH v6 01/16] sched/core: Allow sched_setattr() to use the current policy
>    <20190115101513.2822-2-patrick.bellasi@arm.com>
> 
> we can call __sched_setscheduler() with:
> 
>    attr->sched_flags & SCHED_FLAG_KEEP_POLICY
> 
> whenever we want just to change the clamp values of a task without
> changing its class. Thus, we can end up returning from
> __sched_setscheduler() without doing an actual dequeue/enqueue.

I don't see that happening.. when KEEP_POLICY we set attr.sched_policy =
SETPARAM_POLICY. That is then checked again in __setscheduler_param(),
which is in the middle of that dequeue/enqueue.

Also, and this might be 'broken', SETPARAM_POLICY _does_ reset all the
other attributes, it only preserves policy, but it will (re)set nice
level for example (see that same function).

So maybe we want to introduce another (few?) FLAG_KEEP flag(s) that
preserve the other bits; I'm thinking at least KEEP_PARAM and KEEP_UTIL
or something.


  reply	other threads:[~2019-01-22 13:28 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-15 10:14 [PATCH v6 00/16] Add utilization clamping support Patrick Bellasi
2019-01-15 10:14 ` [PATCH v6 01/16] sched/core: Allow sched_setattr() to use the current policy Patrick Bellasi
2019-01-25 13:56   ` Alessio Balsini
2019-01-15 10:14 ` [PATCH v6 02/16] sched/core: uclamp: Extend sched_setattr() to support utilization clamping Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 03/16] sched/core: uclamp: Map TASK's clamp values into CPU's clamp buckets Patrick Bellasi
2019-01-21 10:15   ` Peter Zijlstra
2019-01-21 12:27     ` Patrick Bellasi
2019-01-21 12:51       ` Peter Zijlstra
2019-01-21 15:05   ` Peter Zijlstra
2019-01-21 15:34     ` Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 04/16] sched/core: uclamp: Add CPU's clamp buckets refcounting Patrick Bellasi
2019-01-21 14:59   ` Peter Zijlstra
2019-01-21 15:23     ` Patrick Bellasi
2019-01-21 16:12       ` Peter Zijlstra
2019-01-21 16:33         ` Patrick Bellasi
2019-01-22  9:45           ` Peter Zijlstra
2019-01-22 10:31             ` Patrick Bellasi
2019-01-21 15:17   ` Peter Zijlstra
2019-01-21 15:54     ` Patrick Bellasi
2019-01-22 10:03       ` Peter Zijlstra
2019-01-22 10:53         ` Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 05/16] sched/core: uclamp: Update CPU's refcount on clamp changes Patrick Bellasi
2019-01-21 15:33   ` Peter Zijlstra
2019-01-21 15:44     ` Patrick Bellasi
2019-01-22  9:37       ` Peter Zijlstra
2019-01-22 10:43         ` Patrick Bellasi
2019-01-22 13:28           ` Peter Zijlstra [this message]
2019-01-22 14:01             ` Patrick Bellasi
2019-01-22 14:57               ` Peter Zijlstra
2019-01-22 15:33                 ` Patrick Bellasi
2019-01-23  9:16                   ` Peter Zijlstra
2019-01-23 14:14                     ` Patrick Bellasi
2019-01-23 18:59                       ` Peter Zijlstra
2019-01-24 11:21                         ` Patrick Bellasi
2019-01-24 12:38                           ` Peter Zijlstra
2019-01-15 10:15 ` [PATCH v6 06/16] sched/core: uclamp: Enforce last task UCLAMP_MAX Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 07/16] sched/core: uclamp: Add system default clamps Patrick Bellasi
2019-01-22 13:56   ` Peter Zijlstra
2019-01-22 14:43     ` Patrick Bellasi
2019-01-22 15:13       ` Peter Zijlstra
2019-01-22 15:41         ` Patrick Bellasi
2019-01-23  9:22           ` Peter Zijlstra
2019-01-23 14:19             ` Patrick Bellasi
2019-01-23 19:10               ` Peter Zijlstra
2019-01-15 10:15 ` [PATCH v6 08/16] sched/cpufreq: uclamp: Add utilization clamping for FAIR tasks Patrick Bellasi
2019-01-22 10:37   ` Rafael J. Wysocki
2019-01-22 11:02     ` Patrick Bellasi
2019-01-22 11:04       ` Rafael J. Wysocki
2019-01-22 11:27         ` Patrick Bellasi
2019-01-22 15:21   ` Peter Zijlstra
2019-01-22 15:45     ` Patrick Bellasi
2019-01-22 17:13   ` Peter Zijlstra
2019-01-22 18:18     ` Patrick Bellasi
2019-01-23  9:52       ` Peter Zijlstra
2019-01-23 14:24         ` Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 09/16] sched/cpufreq: uclamp: Add utilization clamping for RT tasks Patrick Bellasi
2019-01-22 12:30   ` Quentin Perret
2019-01-22 12:37     ` Patrick Bellasi
2019-01-23 10:28   ` Peter Zijlstra
2019-01-23 14:33     ` Patrick Bellasi
2019-01-23 10:49   ` Peter Zijlstra
2019-01-23 14:40     ` Patrick Bellasi
2019-01-23 20:11       ` Peter Zijlstra
2019-01-24 12:30         ` Patrick Bellasi
2019-01-24 12:38           ` Patrick Bellasi
2019-01-24 15:12             ` Peter Zijlstra
2019-01-24 16:00               ` Patrick Bellasi
2019-01-24 15:31           ` Peter Zijlstra
2019-01-24 16:14             ` Patrick Bellasi
2019-01-24 15:33           ` Peter Zijlstra
2019-01-24 15:15   ` Peter Zijlstra
2019-01-24 16:05     ` Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 10/16] sched/core: Add uclamp_util_with() Patrick Bellasi
2019-01-23 13:33   ` Peter Zijlstra
2019-01-23 14:51     ` Patrick Bellasi
2019-01-23 19:22       ` Peter Zijlstra
2019-01-15 10:15 ` [PATCH v6 11/16] sched/fair: Add uclamp support to energy_compute() Patrick Bellasi
2019-01-22 12:13   ` Quentin Perret
2019-01-22 12:45     ` Patrick Bellasi
2019-01-22 13:29       ` Quentin Perret
2019-01-22 14:26         ` Patrick Bellasi
2019-01-22 14:39           ` Quentin Perret
2019-01-22 15:01             ` Patrick Bellasi
2019-01-22 15:14               ` Quentin Perret
2019-01-15 10:15 ` [PATCH v6 12/16] sched/core: uclamp: Extend CPU's cgroup controller Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 13/16] sched/core: uclamp: Propagate parent clamps Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 14/16] sched/core: uclamp: Map TG's clamp values into CPU's clamp buckets Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 15/16] sched/core: uclamp: Use TG's clamps to restrict TASK's clamps Patrick Bellasi
2019-01-15 10:15 ` [PATCH v6 16/16] sched/core: uclamp: Update CPU's refcount on TG's clamp changes Patrick Bellasi

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