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From: Aubrey Li <aubrey.intel@gmail.com>
To: Aaron Lu <aaron.lwe@gmail.com>
Cc: "Phil Auld" <pauld@redhat.com>,
	"Vineeth Remanan Pillai" <vpillai@digitalocean.com>,
	"Tim Chen" <tim.c.chen@linux.intel.com>,
	"Julien Desfossez" <jdesfossez@digitalocean.com>,
	"Nishanth Aravamudan" <naravamudan@digitalocean.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Ingo Molnar" <mingo@kernel.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Paul Turner" <pjt@google.com>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Linux List Kernel Mailing" <linux-kernel@vger.kernel.org>,
	"Dario Faggioli" <dfaggioli@suse.com>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Greg Kerr" <kerrnel@google.com>,
	"Valentin Schneider" <valentin.schneider@arm.com>,
	"Mel Gorman" <mgorman@techsingularity.net>,
	"Pawan Gupta" <pawan.kumar.gupta@linux.intel.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>
Subject: Re: [RFC PATCH v4 00/19] Core scheduling v4
Date: Thu, 5 Mar 2020 21:45:15 +0800	[thread overview]
Message-ID: <CAERHkrunq=BqB=NmS2b_BfjePX2+nNpbv1EfTWw5rExbvYHyJw@mail.gmail.com> (raw)
In-Reply-To: <20200228025405.GA634650@ziqianlu-desktop.localdomain>

On Fri, Feb 28, 2020 at 10:54 AM Aaron Lu <aaron.lwe@gmail.com> wrote:
>
> When the core wide weight is somewhat balanced, yes I definitely agree.
> But when core wide weight mismatch a lot, I'm not so sure since if these
> high weight task is spread among cores, with the feature of core
> scheduling, these high weight tasks can get better performance.

It depends.

Say TaskA(cookie 1) and TaskB(cookie1) has high weight,
TaskC(cookie 2) and Task D(cookie 2) has low weight.
And we have two cores 4 CPU.

If we dispatch
- TaskA and TaskB on Core0,
- TaskC and TaskD on Core1,

with coresched enabled, all 4 tasks can run all the time.

But if we dispatch
- TaskA on Core0.CPU0, TaskB on Core1.CPU2,
- TaskC on Core0.CPU1, TaskB on Core1.CPU3,

with coresched enabled, when TaskC is running, TaskA will be forced
off CPU and replaced with a forced idle thread.

Things get worse if TaskA and TaskB share some data and can get
benefit from the core level cache.

> So this appeared to me like a question of: is it desirable to protect/enhance
> high weight task performance in the presence of core scheduling?

This sounds to me a policy VS mechanism question. Do you have any idea
how to spread high weight task among the cores with coresched enabled?

Thanks,
-Aubrey

  reply	other threads:[~2020-03-05 13:45 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-30 18:33 [RFC PATCH v4 00/19] Core scheduling v4 Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 01/19] stop_machine: Fix stop_cpus_in_progress ordering Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 02/19] sched: Fix kerneldoc comment for ia64_set_curr_task Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 03/19] sched: Wrap rq::lock access Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 04/19] sched/{rt,deadline}: Fix set_next_task vs pick_next_task Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 05/19] sched: Add task_struct pointer to sched_class::set_curr_task Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 06/19] sched/fair: Export newidle_balance() Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 07/19] sched: Allow put_prev_task() to drop rq->lock Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 08/19] sched: Rework pick_next_task() slow-path Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 09/19] sched: Introduce sched_class::pick_task() Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 10/19] sched: Core-wide rq->lock Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 11/19] sched: Basic tracking of matching tasks Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 12/19] sched: A quick and dirty cgroup tagging interface Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 13/19] sched: Add core wide task selection and scheduling Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 14/19] sched/fair: Add a few assertions Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 15/19] sched: Trivial forced-newidle balancer Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 16/19] sched: Debug bits Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 17/19] sched/fair: wrapper for cfs_rq->min_vruntime Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 18/19] sched/fair: core wide vruntime comparison Vineeth Remanan Pillai
2019-10-30 18:33 ` [RFC PATCH v4 19/19] sched/fair : Wake up forced idle siblings if needed Vineeth Remanan Pillai
2019-10-31 11:42 ` [RFC PATCH v4 00/19] Core scheduling v4 Li, Aubrey
2019-11-01 11:33   ` Li, Aubrey
2019-11-08  3:20     ` Li, Aubrey
2019-10-31 18:42 ` Phil Auld
2019-11-01 14:03   ` Vineeth Remanan Pillai
2019-11-01 16:35     ` Greg Kerr
2019-11-01 18:07       ` Dario Faggioli
2019-11-12  1:45     ` Dario Faggioli
2019-11-13 17:16       ` Tim Chen
2020-01-02  2:28       ` Aubrey Li
2020-01-10 23:19         ` Tim Chen
2019-11-11 19:10 ` Tim Chen
2020-01-14  1:12   ` Tim Chen
2020-01-14 15:40     ` Vineeth Remanan Pillai
2020-01-15  3:43       ` Li, Aubrey
2020-01-15 19:33         ` Tim Chen
2020-01-16  1:45           ` Aubrey Li
2020-01-17 16:00             ` Vineeth Remanan Pillai
2020-01-22 18:04               ` Gruza, Agata
2020-01-28  2:40       ` Dario Faggioli
     [not found]         ` <CANaguZDDpzrzdTmvjXvCmV2c+wBt6mXWSz4Vn-LJ-onc_Oj=yw@mail.gmail.com>
2020-02-01 15:31           ` Dario Faggioli
2020-02-06  0:28       ` Tim Chen
2020-02-06 22:37         ` Julien Desfossez
2020-02-12 23:07         ` Julien Desfossez
2020-02-13 18:37           ` Tim Chen
2020-02-14  6:10             ` Aubrey Li
     [not found]               ` <CANaguZC40mDHfL1H_9AA7H8cyd028t9PQVRqQ3kB4ha8R7hhqg@mail.gmail.com>
2020-02-15  6:01                 ` Aubrey Li
     [not found]                   ` <CANaguZBj_x_2+9KwbHCQScsmraC_mHdQB6uRqMTYMmvhBYfv2Q@mail.gmail.com>
2020-02-21 23:20                     ` Julien Desfossez
2020-03-17  0:55                       ` Joel Fernandes
2020-03-17 19:07                         ` Tim Chen
2020-03-17 20:18                           ` Tim Chen
2020-03-18  1:10                             ` Joel Fernandes
2020-03-17 21:17                           ` Thomas Gleixner
2020-03-17 21:58                             ` Tim Chen
2020-03-18  1:03                             ` Joel Fernandes
2020-03-18  2:30                               ` Joel Fernandes
2020-03-18  0:52                           ` Joel Fernandes
2020-03-18 11:53                             ` Thomas Gleixner
2020-03-19  1:54                               ` Joel Fernandes
2020-02-25  3:44               ` Aaron Lu
2020-02-25  5:32                 ` Aubrey Li
2020-02-25  7:34                   ` Aaron Lu
2020-02-25 10:40                     ` Aubrey Li
2020-02-25 11:21                       ` Aaron Lu
2020-02-25 13:41                         ` Aubrey Li
     [not found]                 ` <CANaguZD205ccu1V_2W-QuMRrJA9SjJ5ng1do4NCdLy8NDKKrbA@mail.gmail.com>
2020-02-26  3:13                   ` Aaron Lu
2020-02-26  7:21                   ` Aubrey Li
     [not found]                     ` <CANaguZDQZg-Z6aNpeLcjQ-cGm3X8CQOkZ_hnJNUyqDRM=yVDFQ@mail.gmail.com>
2020-02-27  4:45                       ` Aubrey Li
2020-02-28 23:55                       ` Tim Chen
2020-03-03 14:59                         ` Li, Aubrey
2020-03-03 23:54                           ` Li, Aubrey
2020-03-05  4:33                             ` Aaron Lu
2020-03-05  6:10                               ` Li, Aubrey
2020-03-05  8:52                                 ` Aaron Lu
2020-02-27  2:04                   ` Aaron Lu
2020-02-27 14:10                     ` Phil Auld
2020-02-27 14:37                       ` Aubrey Li
2020-02-28  2:54                       ` Aaron Lu
2020-03-05 13:45                         ` Aubrey Li [this message]
2020-03-06  2:41                           ` Aaron Lu
2020-03-06 18:06                             ` Tim Chen
2020-03-06 18:33                               ` Phil Auld
2020-03-06 21:44                                 ` Tim Chen
2020-03-07  3:13                                   ` Aaron Lu

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