From: Mel Gorman <mgorman@suse.de>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, bristot@redhat.com,
valentin.schneider@arm.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/3 v2] sched/fair: don't set LBF_ALL_PINNED unnecessarily
Date: Mon, 11 Jan 2021 15:42:26 +0000 [thread overview]
Message-ID: <20210111154226.GG3524@suse.de> (raw)
In-Reply-To: <20210107103325.30851-3-vincent.guittot@linaro.org>
On Thu, Jan 07, 2021 at 11:33:24AM +0100, Vincent Guittot wrote:
> Setting LBF_ALL_PINNED during active load balance is only valid when there
> is only 1 running task on the rq otherwise this ends up increasing the
> balance interval whereas other tasks could migrate after the next interval
> once they become cache-cold as an example.
>
> LBF_ALL_PINNED flag is now always set it by default. It is then cleared
> when we find one task that can be pulled when calling detach_tasks() or
> during active migration.
>
> Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
When reviewing this, I found it curious that sched_nr_migrate_break is
a const instead of a #define. It's not clear why as it only appears to
exist in case sysctl_sched_nr_migrate is set higher than 32 to prevent
rq lock starvation.
With your patch, s/atleast/at least/ in the comments if there is another
version.
Otherwise, I didn't spot a real problem so
Acked-by: Mel Gorman <mgorman@suse.de>
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2021-01-11 15:43 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 10:33 [PATCH 0/3 v2] Reduce number of active LB Vincent Guittot
2021-01-07 10:33 ` [PATCH 1/3 v2] sched/fair: skip idle cfs_rq Vincent Guittot
2021-01-11 14:46 ` Mel Gorman
2021-01-14 11:29 ` [tip: sched/core] sched/fair: Skip " tip-bot2 for Vincent Guittot
2021-01-07 10:33 ` [PATCH 2/3 v2] sched/fair: don't set LBF_ALL_PINNED unnecessarily Vincent Guittot
2021-01-07 11:26 ` Valentin Schneider
[not found] ` <BN8PR12MB2978EC9CFBAF529C527D05919AAF0@BN8PR12MB2978.namprd12.prod.outlook.com>
2021-01-07 16:00 ` Vincent Guittot
2021-01-11 15:42 ` Mel Gorman [this message]
2021-01-14 11:29 ` [tip: sched/core] sched/fair: Don't " tip-bot2 for Vincent Guittot
2021-01-07 10:33 ` [PATCH 3/3 v2] sched/fair: reduce cases for active balance Vincent Guittot
2021-01-07 11:26 ` Valentin Schneider
2021-01-07 12:20 ` Vincent Guittot
2021-01-07 17:40 ` Valentin Schneider
2021-01-08 8:11 ` Vincent Guittot
2021-01-08 14:36 ` Valentin Schneider
2021-01-12 9:16 ` Mel Gorman
2021-01-14 11:29 ` [tip: sched/core] sched/fair: Reduce " tip-bot2 for Vincent Guittot
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