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From: Wanpeng Li <kernellwp@gmail.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Todd Kjos <tkjos@google.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	quentin.perret@linaro.org, chris.redpath@arm.com,
	steven.sistare@oracle.com, subhra.mazumdar@oracle.com,
	songliubraving@fb.com
Subject: Re: [PATCH V3 0/2] sched/fair: Fallback to sched-idle CPU in absence of idle CPUs
Date: Mon, 9 Dec 2019 11:50:12 +0800	[thread overview]
Message-ID: <CANRm+Cytg1hDjxM6oxNyTNWztQdCSpaCoUy7KO8zmrv-muABLw@mail.gmail.com> (raw)
In-Reply-To: <cover.1561523542.git.viresh.kumar@linaro.org>

On Wed, 26 Jun 2019 at 13:07, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> Hi,
>
> We try to find an idle CPU to run the next task, but in case we don't
> find an idle CPU it is better to pick a CPU which will run the task the
> soonest, for performance reason.
>
> A CPU which isn't idle but has only SCHED_IDLE activity queued on it
> should be a good target based on this criteria as any normal fair task
> will most likely preempt the currently running SCHED_IDLE task
> immediately. In fact, choosing a SCHED_IDLE CPU over a fully idle one
> shall give better results as it should be able to run the task sooner
> than an idle CPU (which requires to be woken up from an idle state).
>
> This patchset updates both fast and slow paths with this optimization.
>
> Testing is done with the help of rt-app currently and here are the
> details:
>
> - Tested on Octacore Hikey platform (all CPUs change frequency
>   together).
>
> - rt-app json [1] creates few tasks and we monitor the scheduling
>   latency for them by looking at "wu_lat" field (usec).
>
> - The histograms are created using
>   https://github.com/adkein/textogram: textogram -a 0 -z 1000 -n 10
>
> - the stats are accumulated using: https://github.com/nferraz/st

Hi Viresh,

Thanks for the great work! Could you give the whole commad-line for us testing?

    Wanpeng

  parent reply	other threads:[~2019-12-09  3:50 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-26  5:06 [PATCH V3 0/2] sched/fair: Fallback to sched-idle CPU in absence of idle CPUs Viresh Kumar
2019-06-26  5:06 ` [PATCH V3 1/2] sched: Start tracking SCHED_IDLE tasks count in cfs_rq Viresh Kumar
2019-07-25 16:15   ` [tip:sched/core] sched/fair: " tip-bot for Viresh Kumar
2019-06-26  5:06 ` [PATCH V3 2/2] sched/fair: Fallback to sched-idle CPU if idle CPU isn't found Viresh Kumar
2019-06-29  1:16   ` Subhra Mazumdar
2019-07-01  8:03     ` Viresh Kumar
2019-07-01 22:08       ` Subhra Mazumdar
2019-07-02  8:35         ` Peter Zijlstra
2019-07-02 16:32           ` Subhra Mazumdar
2019-07-25 16:16   ` [tip:sched/core] sched/fair: Fall back " tip-bot for Viresh Kumar
2019-07-01 13:43 ` [PATCH V3 0/2] sched/fair: Fallback to sched-idle CPU in absence of idle CPUs Peter Zijlstra
2019-07-03  9:13   ` Viresh Kumar
2019-12-09  3:50 ` Wanpeng Li [this message]
2019-12-10  6:33   ` Viresh Kumar
2019-12-10 11:15     ` Wanpeng Li

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