From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Yun Hsiang <hsiang023167@gmail.com>
Cc: peterz@infradead.org, linux-kernel@vger.kernel.org,
qais.yousef@arm.com, patrick.bellasi@matbug.net
Subject: Re: [PATCH v2 1/1] sched/uclamp: add SCHED_FLAG_UTIL_CLAMP_RESET flag to reset uclamp
Date: Thu, 15 Oct 2020 13:56:09 +0200 [thread overview]
Message-ID: <c0aacfa8-225d-a529-be9b-d68993104c76@arm.com> (raw)
In-Reply-To: <20201014150034.GA502296@ubuntu>
On 14/10/2020 17:00, Yun Hsiang wrote:
> On Tue, Oct 13, 2020 at 10:25:48PM +0200, Dietmar Eggemann wrote:
>> Hi Yun,
>>
>> On 12/10/2020 18:31, Yun Hsiang wrote:
[...]
> The tg uclamp value may also change. If top-app's cpu.uclamp.min change
> to 50 (~500), then task A's effective uclamp min value is 300 not ~500.
> We can set task A's uclamp to 1024, it will be restricted by the tg.
> But when task A move to root group, it's effective uclamp min value
> will be 1024 not 0. If a task is in root group and it doesn't want to
> control it's uclamp, the effective uclamp min value of that task should be 0.
> So I think reset functionality is needed.
OK, looks like the intended solution { a) or b) in
https://lkml.kernel.org/r/87zh4ohnf9.derkling@matbug.net} is not really
feasible.
So we do need the uclamp reset to enable throughout the entire lifetime
of task p 'p is !user_defined -> p is controlled by taskgroup hierarchy)'.
prev parent reply other threads:[~2020-10-15 12:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-12 16:31 [PATCH v2 1/1] sched/uclamp: add SCHED_FLAG_UTIL_CLAMP_RESET flag to reset uclamp Yun Hsiang
2020-10-13 8:21 ` Patrick Bellasi
2020-10-13 10:29 ` Qais Yousef
2020-10-13 11:46 ` Patrick Bellasi
2020-10-13 13:32 ` Qais Yousef
2020-10-13 16:52 ` Patrick Bellasi
2020-10-14 16:15 ` Yun Hsiang
2020-10-13 20:25 ` Dietmar Eggemann
2020-10-14 14:50 ` Patrick Bellasi
2020-10-15 11:53 ` Dietmar Eggemann
2020-10-14 15:00 ` Yun Hsiang
2020-10-15 11:56 ` Dietmar Eggemann [this message]
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