From: Valentin Schneider <valentin.schneider@arm.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>,
Vincent Guittot <vincent.guittot@linaro.org>,
Ingo Molnar <mingo@kernel.org>,
pauld@redhat.com, srikar@linux.vnet.ibm.com,
quentin.perret@arm.com, dietmar.eggemann@arm.com,
Morten.Rasmussen@arm.com, hdanton@sina.com, parth@linux.ibm.com,
riel@surriel.com, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] sched, fair: Allow a small degree of load imbalance between SD_NUMA domains
Date: Thu, 19 Dec 2019 14:23:33 +0000 [thread overview]
Message-ID: <019ceada-998c-8e5e-74fa-9606c922e096@arm.com> (raw)
In-Reply-To: <83a9363b-a044-845a-d37c-bf2ca7c8a09e@arm.com>
On 19/12/2019 11:46, Valentin Schneider wrote:
> As for picking values, right now we have
>
> 125 (default) / 117 (LLC domain) / 110 (SMT domain)
>
> We could have
>
> >> 2 (25%), >> 3 (12.5%), >> 4 (6.25%).
>
Hmph, I see that task_numa_migrate() starts with a slightly different value
(112), and does the same halving pattern as wake_affine_weight():
x = 100 + (sd->imbalance_pct - 100) / 2;
The 112 could use >> 3 (12.5%); the halving is just an extra shift with the
suggested changes.
> It's not strictly equivalent but IMO the whole imbalance_pct thing isn't
> very precise anyway; just needs to be good enough on a sufficient number of
> topologies.
>
>
>
>>> + env->imbalance = 0;
>>> +
>>> return;
>>> }
>>>
next prev parent reply other threads:[~2019-12-19 14:23 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-18 15:44 [PATCH] sched, fair: Allow a small degree of load imbalance between SD_NUMA domains Mel Gorman
2019-12-18 18:50 ` Valentin Schneider
2019-12-18 22:50 ` Mel Gorman
2019-12-19 11:56 ` Valentin Schneider
2019-12-19 10:02 ` Peter Zijlstra
2019-12-19 11:46 ` Valentin Schneider
2019-12-19 14:23 ` Valentin Schneider [this message]
2019-12-19 15:23 ` Mel Gorman
2019-12-18 18:54 ` Valentin Schneider
2019-12-19 2:58 ` Rik van Riel
2019-12-19 8:41 ` Mel Gorman
2019-12-19 10:04 ` Peter Zijlstra
2019-12-19 14:45 ` Vincent Guittot
2019-12-19 15:16 ` Valentin Schneider
2019-12-19 15:18 ` Mel Gorman
2019-12-19 15:41 ` Vincent Guittot
2019-12-19 15:58 ` Mel Gorman
2019-12-20 13:00 ` Srikar Dronamraju
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