From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: mingo@redhat.com, juri.lelli@redhat.com,
dietmar.eggemann@arm.com, rostedt@goodmis.org,
bsegall@google.com, mgorman@suse.de,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/fair : Improve update_sd_pick_busiest for spare capacity case
Date: Wed, 8 Jan 2020 12:43:10 +0100 [thread overview]
Message-ID: <20200108114310.GD2844@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1576839893-26930-1-git-send-email-vincent.guittot@linaro.org>
On Fri, Dec 20, 2019 at 12:04:53PM +0100, Vincent Guittot wrote:
> Similarly to calculate_imbalance() and find_busiest_group(), using the
> number of idle CPUs when there is only 1 CPU in the group is not efficient
> because we can't make a difference between a CPU running 1 task and a CPU
> running dozens of small tasks competing for the same CPU but not enough
> to overload it. More generally speaking, we should use the number of
> running tasks when there is the same number of idle CPUs in a group instead
> of blindly select the 1st one.
>
> When the groups have spare capacity and the same number of idle CPUs, we
> compare the number of running tasks to select the busiest group.
>
Thanks!
next prev parent reply other threads:[~2020-01-08 11:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-20 11:04 Vincent Guittot
2020-01-08 11:43 ` Peter Zijlstra [this message]
2020-01-17 10:08 ` [tip: sched/core] " tip-bot2 for Vincent Guittot
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