From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Vincent Donnefort <vdonnefort@google.com>,
Quentin Perret <qperret@google.com>,
Patrick Bellasi <patrick.bellasi@matbug.net>,
Abhijeet Dharmapurikar <adharmap@quicinc.com>,
Jian-Min <Jian-Min.Liu@mediatek.com>,
Qais Yousef <qais.yousef@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 1/1] sched/pelt: Introduce PELT multiplier
Date: Fri, 2 Sep 2022 09:53:22 +0200 [thread overview]
Message-ID: <6281126b-3b93-86fa-25d6-d637b6c7dd87@arm.com> (raw)
In-Reply-To: <YwyOzgbbUbB+JmSH@hirez.programming.kicks-ass.net>
On 29/08/2022 12:02, Peter Zijlstra wrote:
> On Mon, Aug 29, 2022 at 10:08:13AM +0200, Peter Zijlstra wrote:
>> On Mon, Aug 29, 2022 at 07:54:50AM +0200, Dietmar Eggemann wrote:
>>> From: Vincent Donnefort <vincent.donnefort@arm.com>
[...]
>>> +extern unsigned int sched_pelt_lshift;
>>> +
>>> +/*
>>> + * absolute time |1 |2 |3 |4 |5 |6 |
>>> + * @ mult = 1 --------****************--------****************-
>>> + * @ mult = 2 --------********----------------********---------
>>> + * @ mult = 4 --------****--------------------****-------------
>>> + * clock task mult
>>> + * @ mult = 2 | | |2 |3 | | | | |5 |6 | | |
>>> + * @ mult = 4 | | | | |2|3| | | | | | | | | | |5|6| | | | | | |
>>> + *
>>> + */
>>> +static inline void update_rq_clock_task_mult(struct rq *rq, s64 delta)
>>> +{
>>> + delta <<= READ_ONCE(sched_pelt_lshift);
>>> +
>>> + rq->clock_task_mult += delta;
>>> +
>>> + update_rq_clock_pelt(rq, delta);
>>> +}
>>
>> Hurmph... I'd almost go write you something like
>> static_call()/static_branch() but for immediates.
>>
>> That said; given there's only like 3 options, perhaps a few
>> static_branch() instances work just fine ?
>
> Also, I'm not at all sure about exposing that as an official sysctl.
>
> How about something like so?
[...]
> void update_rq_clock(struct rq *rq)
> --- a/kernel/sched/features.h
> +++ b/kernel/sched/features.h
> @@ -101,3 +101,6 @@ SCHED_FEAT(LATENCY_WARN, false)
>
> SCHED_FEAT(ALT_PERIOD, true)
> SCHED_FEAT(BASE_SLICE, true)
> +
> +SCHED_FEAT(PELT_M2, false)
> +SCHED_FEAT(PELT_M4, false)
The sched features interface would definitely be much less official but
I think it's not useful for Android since they don't mount debugfs anymore.
[...]
next prev parent reply other threads:[~2022-09-02 7:53 UTC|newest]
Thread overview: 61+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-29 5:54 [RFC PATCH 0/1] sched/pelt: Change PELT halflife at runtime Dietmar Eggemann
2022-08-29 5:54 ` [RFC PATCH 1/1] sched/pelt: Introduce PELT multiplier Dietmar Eggemann
2022-08-29 8:08 ` Peter Zijlstra
2022-08-29 10:02 ` Peter Zijlstra
2022-08-29 10:13 ` Vincent Guittot
2022-08-29 14:23 ` Quentin Perret
2022-08-29 14:34 ` Peter Zijlstra
2022-08-29 15:31 ` Quentin Perret
2022-08-29 15:48 ` Quentin Perret
2022-09-02 7:53 ` Dietmar Eggemann
2022-09-02 8:45 ` Peter Zijlstra
2022-09-06 5:49 ` Vincent Guittot
2022-09-08 6:50 ` Dietmar Eggemann
2022-09-02 7:53 ` Dietmar Eggemann [this message]
2022-09-02 8:45 ` Peter Zijlstra
2022-09-20 14:07 ` [RFC PATCH 0/1] sched/pelt: Change PELT halflife at runtime Jian-Min Liu
2022-09-28 17:09 ` Dietmar Eggemann
2022-09-29 9:47 ` Peter Zijlstra
2022-09-29 11:07 ` Dietmar Eggemann
2022-09-29 11:10 ` Kajetan Puchalski
2022-09-29 11:21 ` Peter Zijlstra
2022-09-29 14:41 ` Kajetan Puchalski
2022-10-03 22:57 ` Wei Wang
2022-10-04 9:33 ` Dietmar Eggemann
2022-10-05 16:57 ` Wei Wang
2022-11-07 13:41 ` Peter Zijlstra
2022-11-08 19:48 ` Qais Yousef
2022-11-09 15:49 ` Peter Zijlstra
2022-11-10 13:25 ` Qais Yousef
2023-02-07 10:29 ` Dietmar Eggemann
2023-02-09 16:16 ` Vincent Guittot
2023-02-17 13:54 ` Dietmar Eggemann
2023-02-20 13:54 ` Vincent Guittot
2023-02-21 9:29 ` Vincent Guittot
2023-02-22 20:28 ` Dietmar Eggemann
2023-03-01 10:24 ` Vincent Guittot
2023-02-22 20:13 ` Dietmar Eggemann
2023-03-02 19:36 ` Dietmar Eggemann
2023-02-20 10:13 ` Peter Zijlstra
2023-02-20 13:39 ` Vincent Guittot
2023-02-23 15:37 ` Qais Yousef
2023-03-01 10:39 ` Vincent Guittot
2023-03-01 17:24 ` Qais Yousef
2023-03-02 8:00 ` Vincent Guittot
2023-03-02 19:39 ` Dietmar Eggemann
2023-03-06 19:11 ` Qais Yousef
2023-03-07 13:22 ` Vincent Guittot
2023-03-11 16:55 ` Qais Yousef
2023-03-23 16:29 ` Dietmar Eggemann
2023-04-03 14:45 ` Qais Yousef
2023-04-06 15:58 ` Dietmar Eggemann
2023-04-11 17:51 ` Qais Yousef
2022-11-09 15:18 ` Lukasz Luba
2022-11-10 11:16 ` Dietmar Eggemann
2022-11-10 13:05 ` Peter Zijlstra
2022-11-10 14:59 ` Dietmar Eggemann
2022-11-10 17:51 ` Peter Zijlstra
2022-11-30 18:14 ` Dietmar Eggemann
2022-12-01 13:37 ` Kajetan Puchalski
2022-11-10 12:45 ` Kajetan Puchalski
2022-11-07 9:41 ` Jian-Min Liu (劉建旻)
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