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From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Donnefort <vincent.donnefort@arm.com>
Cc: mingo@redhat.com, vincent.guittot@linaro.org,
	linux-kernel@vger.kernel.org, dietmar.eggemann@arm.com,
	valentin.schneider@arm.com
Subject: Re: [PATCH v3] sched/fair: Fix per-CPU kthread and wakee stacking for asym CPU capacity
Date: Sat, 4 Dec 2021 10:40:40 +0100	[thread overview]
Message-ID: <20211204094040.GN16608@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20211129173115.4006346-1-vincent.donnefort@arm.com>

On Mon, Nov 29, 2021 at 05:31:15PM +0000, Vincent Donnefort wrote:
> select_idle_sibling() has a special case for tasks woken up by a per-CPU
> kthread where the selected CPU is the previous one. For asymmetric CPU
> capacity systems, the assumption was that the wakee couldn't have a
> bigger utilization during task placement than it used to have during the
> last activation. That was not considering uclamp.min which can completely
> change between two task activations and as a consequence mandates the
> fitness criterion asym_fits_capacity(), even for the exit path described
> above.
> 
> Fixes: b4c9c9f15649 ("sched/fair: Prefer prev cpu in asymmetric wakeup path")
> Signed-off-by: Vincent Donnefort <vincent.donnefort@arm.com>
> Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>

Thanks!

  reply	other threads:[~2021-12-04  9:40 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-29 17:31 [PATCH v3] sched/fair: Fix per-CPU kthread and wakee stacking for asym CPU capacity Vincent Donnefort
2021-12-04  9:40 ` Peter Zijlstra [this message]
2021-12-06 15:22 ` [tip: sched/core] " tip-bot2 for Vincent Donnefort

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