From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Juri Lelli <juri.lelli@redhat.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Daniel Bristot de Oliveira <bristot@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/3] sched/fair: reduce cases for active balance
Date: Wed, 6 Jan 2021 17:11:03 +0100 [thread overview]
Message-ID: <X/XhFzKo/Gv+bFsx@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAKfTPtCEV5zzXLM3RNf2-6XhVcDsstHdzh9OKX_j6WviRUVeYw@mail.gmail.com>
On Wed, Jan 06, 2021 at 04:41:04PM +0100, Vincent Guittot wrote:
> Let me try again:
>
> Active balance is triggered for a number of voluntary cases like
> misfit or pinned tasks cases but also after that a number of load
> balance attempts failed to migrate a task. There is no need to use
> active load balance when the group is overloaded because an overloaded
> state means that there is at least one waiting task. Nevertheless, the
> waiting task is not selected and detached until the threshold becomes
> higher than its load. This threshold increases with the number of
> failed lb (see the condition if ((load >> env->sd->nr_balance_failed)
> > env->imbalance) in detach_tasks()) and the waiting task will end up
> to be selected after a number of attempts.
Ah, makes sense now. Thanks!
prev parent reply other threads:[~2021-01-06 16:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-06 13:34 [PATCH 0/3] Reduce number of active LB Vincent Guittot
2021-01-06 13:34 ` [PATCH 1/3] sched/fair: skip idle cfs_rq Vincent Guittot
2021-01-06 15:13 ` Valentin Schneider
2021-01-06 13:34 ` [PATCH 2/3] sched/fair: don't set LBF_ALL_PINNED unnecessarily Vincent Guittot
2021-01-06 15:07 ` Peter Zijlstra
2021-01-06 15:20 ` Vincent Guittot
2021-01-06 15:32 ` Peter Zijlstra
2021-01-06 15:45 ` Vincent Guittot
2021-01-06 15:13 ` Valentin Schneider
2021-01-06 16:04 ` Vincent Guittot
2021-01-06 13:34 ` [PATCH 3/3] sched/fair: reduce cases for active balance Vincent Guittot
2021-01-06 15:13 ` Peter Zijlstra
2021-01-06 15:41 ` Vincent Guittot
2021-01-06 16:11 ` Peter Zijlstra [this message]
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