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From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Quentin Perret <qperret@google.com>
Cc: mingo@redhat.com, peterz@infradead.org,
	vincent.guittot@linaro.org, qais.yousef@arm.com,
	rickyiu@google.com, wvw@google.com, patrick.bellasi@matbug.net,
	xuewen.yan94@gmail.com, linux-kernel@vger.kernel.org,
	kernel-team@android.com
Subject: Re: [PATCH v4 2/2] sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS
Date: Thu, 29 Jul 2021 19:34:14 +0200	[thread overview]
Message-ID: <cb6aaa1d-0bf4-eebc-5ffc-c1e7971564a8@arm.com> (raw)
In-Reply-To: <YP/dEMeULqozIqZd@google.com>

On 27/07/2021 12:16, Quentin Perret wrote:
> On Monday 26 Jul 2021 at 14:56:10 (+0100), Quentin Perret wrote:
>> On Thursday 22 Jul 2021 at 10:47:33 (+0200), Dietmar Eggemann wrote:
>>> (*) This changes the behaviour when setting uclamp values on a DL task.
>>>
>>> Before uclamp values could be set but now, because of
>>>
>>>   void __getparam_dl(struct task_struct *p, struct sched_attr *attr)
>>>     ..
>>>     attr->sched_flags = dl_se->flags
>>>
>>> SCHED_FLAG_UTIL_CLAMP gets overwritten and  __sched_setscheduler() bails in:
>>>
>>>     if (unlikely(policy == p->policy)) {
>>>       ...
>>>       retval = 0;
>>>       goto unlock;
>>>     }
>>>   change:
>>>
>>> I.e. the:
>>>
>>>       if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP)
>>>         goto change;
>>>
>>> can't trigger anymore.
>>
>> Bah, as you said it doesn't seem to be a big deal, but clearly that was
>> unintentional. Let me try and fix this.
> 
> While looking at this I found existing bugs in the area. Fixes are here:
> 
> https://lore.kernel.org/lkml/20210727101103.2729607-1-qperret@google.com/
> 
> And with the above series applied this patch should behave correctly
> now.

It does. Like depicted in

https://lkml.kernel.org/r/e6d103f1-f8ee-cad9-c7c0-c9ea5d0f099a@arm.com

Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

  reply	other threads:[~2021-07-29 17:34 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-19 16:16 [PATCH v4 0/2] A couple of uclamp fixes Quentin Perret
2021-07-19 16:16 ` [PATCH v4 1/2] sched: Fix UCLAMP_FLAG_IDLE setting Quentin Perret
2021-07-21 10:07   ` Dietmar Eggemann
2021-07-21 13:09     ` Quentin Perret
2021-07-22  8:47       ` Dietmar Eggemann
2021-07-27 14:32   ` Qais Yousef
2021-07-19 16:16 ` [PATCH v4 2/2] sched: Skip priority checks with SCHED_FLAG_KEEP_PARAMS Quentin Perret
2021-07-22  8:47   ` Dietmar Eggemann
2021-07-26 13:56     ` Quentin Perret
2021-07-27 10:16       ` Quentin Perret
2021-07-29 17:34         ` Dietmar Eggemann [this message]
2021-07-29 17:31       ` Dietmar Eggemann

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