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From: Subhra Mazumdar <subhra.mazumdar@oracle.com>
To: Aubrey Li <aubrey.intel@gmail.com>
Cc: "Tim Chen" <tim.c.chen@linux.intel.com>,
	"Aaron Lu" <aaron.lu@linux.alibaba.com>,
	"Vineeth Remanan Pillai" <vpillai@digitalocean.com>,
	"Nishanth Aravamudan" <naravamudan@digitalocean.com>,
	"Julien Desfossez" <jdesfossez@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>,
	"Frédéric Weisbecker" <fweisbec@gmail.com>,
	"Kees Cook" <keescook@chromium.org>,
	"Greg Kerr" <kerrnel@google.com>, "Phil Auld" <pauld@redhat.com>,
	"Aaron Lu" <aaron.lwe@gmail.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 v2 11/17] sched: Basic tracking of matching tasks
Date: Thu, 9 May 2019 10:50:03 -0700	[thread overview]
Message-ID: <b2b1b1f6-9790-73c7-8566-031ec28606a7@oracle.com> (raw)
In-Reply-To: <CAERHkrtw3jH1eWn52r+L75k84SeYuvw12A5cbmofiNjoJFhEsw@mail.gmail.com>


>> select_task_rq_* seems to be unchanged. So the search logic to find a cpu
>> to enqueue when a task becomes runnable is same as before and doesn't do
>> any kind of cookie matching.
> Okay, that's true in task wakeup path, and also load_balance seems to pull task
> without checking cookie too. But my system is not over loaded when I tested this
> patch, so there is none or only one task in rq and on the rq's rb
> tree, so this patch
> does not make a difference.
I had same hypothesis for my tests.
>
> The question is, should we do cookie checking for task selecting CPU and load
> balance CPU pulling task?
The basic issue is keeping the CPUs busy. In case of overloaded system,
the trivial new idle balancer should be able to find a matching task
in case of forced idle. More problematic is the lower load scenario when
there aren't any matching task to be found but there are runnable tasks of
other groups. Also wake up code path tries to balance threads across cores
(select_idle_core) first which is opposite of what core scheduling wants.
I will re-run my tests with select_idle_core disabled, but the issue is
on x86 Intel systems (my test rig) the CPU ids are interleaved across cores
so even select_idle_cpu will balance across cores first. May be others have
some better ideas?
>
> Thanks,
> -Aubrey

  reply	other threads:[~2019-05-09 17:55 UTC|newest]

Thread overview: 109+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-23 16:18 [RFC PATCH v2 00/17] Core scheduling v2 Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 01/17] stop_machine: Fix stop_cpus_in_progress ordering Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 02/17] sched: Fix kerneldoc comment for ia64_set_curr_task Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 03/17] sched: Wrap rq::lock access Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 04/17] sched/{rt,deadline}: Fix set_next_task vs pick_next_task Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 05/17] sched: Add task_struct pointer to sched_class::set_curr_task Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 06/17] sched/fair: Export newidle_balance() Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 07/17] sched: Allow put_prev_task() to drop rq->lock Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 08/17] sched: Rework pick_next_task() slow-path Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 09/17] sched: Introduce sched_class::pick_task() Vineeth Remanan Pillai
2019-04-26 14:02   ` Peter Zijlstra
2019-04-26 16:10     ` Vineeth Remanan Pillai
2019-04-29  5:38   ` Aaron Lu
2019-04-23 16:18 ` [RFC PATCH v2 10/17] sched: Core-wide rq->lock Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 11/17] sched: Basic tracking of matching tasks Vineeth Remanan Pillai
2019-04-24  0:08   ` Tim Chen
2019-04-24 20:43     ` Vineeth Remanan Pillai
2019-04-24 22:12       ` Tim Chen
2019-04-25 14:35       ` Phil Auld
2019-05-22 19:52         ` Vineeth Remanan Pillai
2019-04-24  0:17   ` Tim Chen
2019-04-24 20:43     ` Vineeth Remanan Pillai
2019-04-29  3:36   ` Aaron Lu
2019-05-10 13:06     ` Peter Zijlstra
2019-04-29  6:15   ` Aaron Lu
2019-05-01 23:27     ` Tim Chen
2019-05-03  0:06       ` Tim Chen
2019-05-08 15:49         ` Aubrey Li
2019-05-08 18:19           ` Subhra Mazumdar
2019-05-08 18:37             ` Subhra Mazumdar
2019-05-09  0:01               ` Aubrey Li
2019-05-09  0:25                 ` Subhra Mazumdar
2019-05-09  1:38                   ` Aubrey Li
2019-05-09  2:14                     ` Subhra Mazumdar
2019-05-09 15:10                       ` Aubrey Li
2019-05-09 17:50                         ` Subhra Mazumdar [this message]
2019-05-10  0:09                           ` Tim Chen
2019-04-23 16:18 ` [RFC PATCH v2 12/17] sched: A quick and dirty cgroup tagging interface Vineeth Remanan Pillai
2019-04-25 14:26   ` Phil Auld
2019-04-26 14:13     ` Peter Zijlstra
2019-04-26 14:19       ` Phil Auld
2019-05-10 15:12   ` Julien Desfossez
2019-04-23 16:18 ` [RFC PATCH v2 13/17] sched: Add core wide task selection and scheduling Vineeth Remanan Pillai
2019-04-29  7:13   ` Aaron Lu
2019-05-18 15:37   ` Aubrey Li
2019-05-20 13:04     ` Phil Auld
2019-05-20 14:04       ` Vineeth Pillai
2019-05-21  8:19         ` Aubrey Li
2019-05-21 13:24           ` Vineeth Pillai
2019-04-23 16:18 ` [RFC PATCH v2 14/17] sched/fair: Add a few assertions Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 15/17] sched: Trivial forced-newidle balancer Vineeth Remanan Pillai
2019-04-23 23:46   ` Aubrey Li
2019-04-24 14:03     ` Vineeth Remanan Pillai
2019-04-24 14:05     ` Vineeth Remanan Pillai
2019-04-23 16:18 ` [RFC PATCH v2 16/17] sched: Wake up sibling if it has something to run Vineeth Remanan Pillai
2019-04-26 15:03   ` Peter Zijlstra
2019-04-29 12:36     ` Julien Desfossez
2019-04-23 16:18 ` [RFC PATCH v2 17/17] sched: Debug bits Vineeth Remanan Pillai
2019-05-17 17:18   ` Aubrey Li
2019-04-23 18:02 ` [RFC PATCH v2 00/17] Core scheduling v2 Phil Auld
2019-04-23 18:45   ` Vineeth Remanan Pillai
2019-04-29  3:53     ` Aaron Lu
2019-05-06 19:39       ` Julien Desfossez
2019-05-08  2:30         ` Aaron Lu
2019-05-08 17:49           ` Julien Desfossez
2019-05-09  2:11             ` Aaron Lu
2019-05-15 21:36               ` Vineeth Remanan Pillai
2019-04-23 23:25 ` Aubrey Li
2019-04-24 11:19   ` Vineeth Remanan Pillai
2019-05-15 21:39     ` Vineeth Remanan Pillai
2019-04-24 13:13 ` Aubrey Li
2019-04-24 14:00   ` Julien Desfossez
2019-04-25  3:15     ` Aubrey Li
2019-04-25  9:55       ` Ingo Molnar
2019-04-25 14:46         ` Mel Gorman
2019-04-25 18:53           ` Ingo Molnar
2019-04-25 18:59             ` Thomas Gleixner
2019-04-25 19:34               ` Ingo Molnar
2019-04-25 21:31             ` Mel Gorman
2019-04-26  8:42               ` Ingo Molnar
2019-04-26 10:43                 ` Mel Gorman
2019-04-26 18:37                   ` Subhra Mazumdar
2019-04-26 19:49                     ` Mel Gorman
2019-04-26  9:45               ` Ingo Molnar
2019-04-26 10:19                 ` Mel Gorman
2019-04-27  9:06                   ` Ingo Molnar
2019-04-26  9:51               ` Ingo Molnar
2019-04-26 14:15             ` Phil Auld
2019-04-26  2:18         ` Aubrey Li
2019-04-26  9:51           ` Ingo Molnar
2019-04-27  3:51         ` Aubrey Li
2019-04-27  9:17           ` Ingo Molnar
2019-04-27 14:04             ` Aubrey Li
2019-04-27 14:21               ` Ingo Molnar
2019-04-27 15:54                 ` Aubrey Li
2019-04-28  9:33                   ` Ingo Molnar
2019-04-28 10:29                     ` Aubrey Li
2019-04-28 12:17                       ` Ingo Molnar
2019-04-29  2:17                         ` Li, Aubrey
2019-04-29  6:14                           ` Ingo Molnar
2019-04-29 13:25                             ` Li, Aubrey
2019-04-29 15:39                               ` Phil Auld
2019-04-30  1:24                                 ` Aubrey Li
2019-04-29 16:00                               ` Ingo Molnar
2019-04-30  1:34                                 ` Aubrey Li
2019-04-30  4:42                                   ` Ingo Molnar
2019-05-18  0:58                                     ` Li, Aubrey
2019-05-18  1:08                                       ` Li, Aubrey
2019-04-25 14:36 ` Julien Desfossez

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