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From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Mel Gorman <mgorman@techsingularity.net>,
	Mike Galbraith <efault@gmx.de>, Ingo Molnar <mingo@kernel.org>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Aubrey Li <aubrey.li@linux.intel.com>,
	Barry Song <song.bao.hua@hisilicon.com>,
	Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] sched/fair: Scale wakeup granularity relative to nr_running
Date: Tue, 5 Oct 2021 12:28:27 +0200	[thread overview]
Message-ID: <YVwoy30GY61Z4nid@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAKfTPtDc39fCLbQqA2BhC6dsb+MyYYMdk9HUvrU0fRqULuQB-g@mail.gmail.com>

On Wed, Sep 22, 2021 at 08:22:43PM +0200, Vincent Guittot wrote:

> @@ -7161,6 +7162,13 @@ static void check_preempt_wakeup(struct rq *rq,
> struct task_struct *p, int wake_
>                 return;
> 
>         update_curr(cfs_rq_of(se));
> +       delta_exec = se->sum_exec_runtime - se->prev_sum_exec_runtime;
> +       /*
> +        * Ensure that current got a chance to move forward
> +        */
> +       if (delta_exec < sysctl_sched_min_granularity)
> +               return;
> +

I think we tried that at some point; IIRC the problem with this is that
if the interactive task fails to preempt, that preemption is lost. IOW
interactivity suffers.

Basically if you don't want wake-up preemptions, use SCHED_BATCH, then
those tasks will not preempt one another, but the SCHED_NORMAL tasks
will preempt them.

  parent reply	other threads:[~2021-10-05 10:31 UTC|newest]

Thread overview: 59+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-20 14:26 [PATCH 0/2] Scale wakeup granularity relative to nr_running Mel Gorman
2021-09-20 14:26 ` [PATCH 1/2] sched/fair: Remove redundant lookup of rq in check_preempt_wakeup Mel Gorman
2021-09-21  7:21   ` Vincent Guittot
2021-09-21  7:53     ` Mel Gorman
2021-09-21  8:12       ` Vincent Guittot
2021-09-21  8:21       ` Peter Zijlstra
2021-09-21 10:03         ` Mel Gorman
2021-09-20 14:26 ` [PATCH 2/2] sched/fair: Scale wakeup granularity relative to nr_running Mel Gorman
2021-09-21  3:52   ` Mike Galbraith
2021-09-21  5:50     ` Mike Galbraith
2021-09-21  7:04     ` Mike Galbraith
2021-09-21 10:36     ` Mel Gorman
2021-09-21 12:32       ` Mike Galbraith
2021-09-21 14:03         ` Mel Gorman
2021-10-05  9:24         ` Peter Zijlstra
2021-09-22  5:22       ` Mike Galbraith
2021-09-22 13:20         ` Mel Gorman
2021-09-22 14:04           ` Mike Galbraith
2021-09-22 14:15           ` Vincent Guittot
2021-09-22 15:04             ` Mel Gorman
2021-09-22 16:00               ` Vincent Guittot
2021-09-22 17:38                 ` Mel Gorman
2021-09-22 18:22                   ` Vincent Guittot
2021-09-22 18:57                     ` Mel Gorman
2021-09-23  1:47                     ` Mike Galbraith
2021-09-23  8:40                       ` Vincent Guittot
2021-09-23  9:21                         ` Mike Galbraith
2021-09-23 12:41                           ` Vincent Guittot
2021-09-23 13:14                             ` Mike Galbraith
2021-09-27 11:17                             ` Mel Gorman
2021-09-27 14:17                               ` Mike Galbraith
2021-10-04  8:05                                 ` Mel Gorman
2021-10-04 16:37                                   ` Vincent Guittot
2021-10-05  7:41                                     ` Mel Gorman
2021-09-27 14:19                               ` Vincent Guittot
2021-09-27 15:02                                 ` Mel Gorman
2021-09-23 12:24                         ` Phil Auld
2021-10-05 10:36                           ` Peter Zijlstra
2021-10-05 14:12                             ` Phil Auld
2021-10-05 14:32                               ` Peter Zijlstra
2021-10-05 10:28                     ` Peter Zijlstra [this message]
2021-10-05 10:23                   ` Peter Zijlstra
2021-10-05  9:41               ` Peter Zijlstra
2021-09-22 15:05             ` Vincent Guittot
2021-10-05  9:32           ` Peter Zijlstra
2021-10-03  3:07         ` wakeup_affine_weight() is b0rked - was " Mike Galbraith
2021-10-03  7:34           ` Barry Song
2021-10-03 14:52             ` Mike Galbraith
2021-10-03 21:06               ` Barry Song
2021-10-04  1:49                 ` Mike Galbraith
2021-10-04  4:34             ` Mike Galbraith
2021-10-04  9:06               ` Mike Galbraith
2021-10-05  7:47                 ` Mel Gorman
2021-10-05  8:42                   ` Mike Galbraith
2021-10-05  9:31                     ` Mel Gorman
2021-10-06  6:46                       ` Mike Galbraith
2021-10-08  5:06                       ` Mike Galbraith
2021-09-21  8:03   ` Vincent Guittot
2021-09-21 10:45     ` Mel Gorman

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