From: Valentin Schneider <valentin.schneider@arm.com>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH v3 9/9] sched/topology: Define and use shortcut pointers for wakeup sd_flag scan
Date: Thu, 16 Apr 2020 21:54:52 +0100 [thread overview]
Message-ID: <jhjsgh36tib.mognet@arm.com> (raw)
In-Reply-To: <CAKfTPtDFD7KMcSK-2_LP-_APN2m05pWVhzKvJOVnD+Nacn846w@mail.gmail.com>
On 16/04/20 16:58, Vincent Guittot wrote:
>> ---
>> if (wake_flags & WF_TTWU) {
>> if (want_affine) {
>> // We can cache that at topology buildup
>> sd = highest_flag_domain(cpu, SD_WAKE_AFFINE);
>>
>> if (cpumask_test_cpu(prev_cpu, sched_domain_span(sd) &&
>> cpu != prev_cpu)
>> new_cpu = wake_affine();
>>
>> }
>> // Directly go to select_idle_sibling()
>> goto sis;
>> }
>>
>> // !want_affine logic here
>> ---
>>
>> This in turns mean we could get rid of SD_BALANCE_WAKE entirely... I'm a
>> bit more reluctant to that only because the last SD_BALANCE_WAKE setter was
>
> For now, we should probably skip the additional test above: "if
> (wake_flags & WF_TTWU) {" and keep SD_BALANCE_WAKE so we will continue
> to loop in case of !want_affine.
>
> We can imagine that we might want at the end to be a bit more smart
> for SD_BALANCE_WAKE and the slow path... like with the latency nice
> proposal and latency-nice=19 as a example
>
Good point. I'll go for the first option and see where I end up; I'd like
to cache the other domain pointers if possible, I'll do some benchmarking
and see if I can do that without another switch case.
>> removed fairly recently, see
>> a526d466798d ("sched/topology: Remove SD_BALANCE_WAKE on asymmetric capacity systems")
next prev parent reply other threads:[~2020-04-16 20:55 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-15 21:05 [PATCH v3 0/9] sched: Streamline select_task_rq() & select_task_rq_fair() Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 1/9] sched/fair: find_idlest_group(): Remove unused sd_flag parameter Valentin Schneider
2020-04-16 7:40 ` Vincent Guittot
2020-05-01 18:22 ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 2/9] sched/debug: Make sd->flags sysctl read-only Valentin Schneider
2020-05-01 18:22 ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 3/9] sched: Remove checks against SD_LOAD_BALANCE Valentin Schneider
2020-05-01 18:22 ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 4/9] sched/topology: Kill SD_LOAD_BALANCE Valentin Schneider
2020-05-01 18:22 ` [tip: sched/core] " tip-bot2 for Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 5/9] sched: Add WF_TTWU, WF_EXEC wakeup flags Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 6/9] sched: Kill select_task_rq()'s sd_flag parameter Valentin Schneider
2020-04-16 7:42 ` Vincent Guittot
2020-04-16 10:24 ` Valentin Schneider
2020-04-16 10:47 ` Peter Zijlstra
2020-04-16 11:43 ` Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 7/9] sched/fair: Dissociate wakeup decisions from SD flag value Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 8/9] sched/fair: Split select_task_rq_fair want_affine logic Valentin Schneider
2020-04-15 21:05 ` [PATCH v3 9/9] sched/topology: Define and use shortcut pointers for wakeup sd_flag scan Valentin Schneider
2020-04-16 7:46 ` Vincent Guittot
2020-04-16 10:24 ` Valentin Schneider
2020-04-16 13:04 ` Dietmar Eggemann
2020-04-16 13:36 ` Vincent Guittot
2020-04-16 15:27 ` Valentin Schneider
2020-04-16 15:58 ` Vincent Guittot
2020-04-16 20:54 ` Valentin Schneider [this message]
2020-04-16 10:58 ` [PATCH v3 0/9] sched: Streamline select_task_rq() & select_task_rq_fair() Peter Zijlstra
2020-04-16 11:00 ` Peter Zijlstra
2020-04-16 11:02 ` Valentin Schneider
2020-04-16 13:00 ` Vincent Guittot
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