From: Dietmar Eggemann <dietmar.eggemann@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Qais Yousef <qyousef@layalina.io>,
Kajetan Puchalski <kajetan.puchalski@arm.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Vincent Donnefort <vdonnefort@google.com>,
Quentin Perret <qperret@google.com>,
Abhijeet Dharmapurikar <adharmap@quicinc.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] sched: Consider CPU contention in frequency & load-balance busiest CPU selection
Date: Thu, 4 May 2023 19:11:12 +0200 [thread overview]
Message-ID: <f4501e45-3cfc-b605-b065-5693427ab877@arm.com> (raw)
In-Reply-To: <CAKfTPtDh_aQn15to7E9JypVXarFVcEL+jiWJMV6J7-Gijj9SyQ@mail.gmail.com>
On 03/05/2023 18:08, Vincent Guittot wrote:
> On Thu, 6 Apr 2023 at 17:50, Dietmar Eggemann <dietmar.eggemann@arm.com> wrote:
>>
>> Use new cpu_boosted_util_cfs() instead of cpu_util_cfs().
>>
>> The former returns max(util_avg, runnable_avg) capped by max CPU
>> capacity. CPU contention is thereby considered through runnable_avg.
>>
>> The change in load-balance only affects migration type `migrate_util`.
>
> would be good to get some figures to show the benefit
Yes. Will add JankbenchX on Pixel6 for sugov_get_util() and `perf bench
sched messaging` on Ampere Altra with the next version.
>> Suggested-by: Vincent Guittot <vincent.guittot@linaro.org>
>> Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
>> ---
>> kernel/sched/cpufreq_schedutil.c | 3 ++-
>> kernel/sched/fair.c | 2 +-
>> kernel/sched/sched.h | 19 +++++++++++++++++++
>> 3 files changed, 22 insertions(+), 2 deletions(-)
>>
>> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
>> index e3211455b203..728b186cd367 100644
>> --- a/kernel/sched/cpufreq_schedutil.c
>> +++ b/kernel/sched/cpufreq_schedutil.c
>> @@ -158,7 +158,8 @@ static void sugov_get_util(struct sugov_cpu *sg_cpu)
>> struct rq *rq = cpu_rq(sg_cpu->cpu);
>>
>> sg_cpu->bw_dl = cpu_bw_dl(rq);
>> - sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),
>> + sg_cpu->util = effective_cpu_util(sg_cpu->cpu,
>> + cpu_boosted_util_cfs(sg_cpu->cpu),
>
> Shouldn't we have a similar change in feec to estimate correctly which
> OPP/ freq will be selected by schedutil ?
Yes, this should be more correct. Schedutil and EAS should see the world
the same way.
But IMHO only for the
find_energy_efficient_cpu()
compute_energy()
eenv_pd_max_util()
util = cpu_util_next(..., p, ...)
effective_cpu_util(..., util, FREQUENCY_UTIL, ...)
^^^^^^^^^^^^^^
case.
Not sure what I do for the task contribution? We use
task_util(p)/_task_util_est(p) inside cpu_util_next().
Do I have to consider p->se.avg.runnable_avg as well?
I don't think that we have a testcase showing any diff for this change
individually though.
[...]
next prev parent reply other threads:[~2023-05-04 17:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-06 15:50 [PATCH 0/1] sched: Consider CPU contention in frequency & load-balance busiest CPU selection Dietmar Eggemann
2023-04-06 15:50 ` [PATCH 1/1] " Dietmar Eggemann
2023-04-29 14:58 ` Peter Zijlstra
2023-05-03 17:13 ` Dietmar Eggemann
2023-05-04 15:23 ` Qais Yousef
2023-05-11 15:25 ` Dietmar Eggemann
2023-05-15 19:18 ` Qais Yousef
2023-05-03 16:08 ` Vincent Guittot
2023-05-04 17:11 ` Dietmar Eggemann [this message]
2023-05-05 8:22 ` Vincent Guittot
2023-05-05 18:16 ` Dietmar Eggemann
2023-05-05 7:10 ` Chen Yu
2023-05-05 18:02 ` Dietmar Eggemann
2023-05-07 2:19 ` Chen Yu
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