From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Rik van Riel <riel@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Michael Neuling <mikey@neuling.org>,
Ingo Molnar <mingo@kernel.org>,
jhladky@redhat.com, ktkhai@parallels.com,
tim.c.chen@linux.intel.com,
Nicolas Pitre <nicolas.pitre@linaro.org>
Subject: Re: [PATCH 1/2] sched: fix and clean up calculate_imbalance
Date: Tue, 29 Jul 2014 16:59:10 +0200 [thread overview]
Message-ID: <20140729145910.GH3935@laptop> (raw)
In-Reply-To: <CAKfTPtDuFLOf3Kzt4PSdox3HpBoz9aWXb-QzkibAL-Z4xBm=tw@mail.gmail.com>
On Tue, Jul 29, 2014 at 11:04:50AM +0200, Vincent Guittot wrote:
> > In situations where all the domains are overloaded, or where only the
> > busiest domain is overloaded, that code is also superfluous, since
> > the normal env->imbalance calculation will figure out how much to move.
> > Remove the load_above_capacity calculation.
>
> IMHO, we should not remove that part which is used by prefer_sibling
>
> Originally, we had 2 type of busiest group: overloaded or imbalanced.
> You add a new one which has only a avg_load higher than other so you
> should handle this new case and keep the other ones unchanged
Right, so we want that code for overloaded -> overloaded migrations such
as not to cause idle cpus in an attempt to balance things. Idle cpus are
worse than imbalance.
But in case of overloaded/imb -> !overloaded migrations we can allow it,
and in fact want to allow it in order to balance idle cpus.
next prev parent reply other threads:[~2014-07-29 14:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-28 18:16 [PATCH 0/2] load balancing fixes riel
2014-07-28 18:16 ` [PATCH 1/2] sched: fix and clean up calculate_imbalance riel
2014-07-29 9:04 ` Vincent Guittot
2014-07-29 14:53 ` Rik van Riel
2014-07-29 15:31 ` Vincent Guittot
2014-07-29 15:39 ` Rik van Riel
2014-07-29 14:59 ` Peter Zijlstra [this message]
2014-07-29 15:15 ` Rik van Riel
2014-07-29 15:49 ` Peter Zijlstra
2014-07-29 17:04 ` Rik van Riel
2014-07-29 15:27 ` Peter Zijlstra
2014-07-30 9:32 ` Vincent Guittot
2014-07-30 10:13 ` Peter Zijlstra
2014-08-12 14:52 ` [tip:sched/core] sched/fair: Allow calculate_imbalance() to move idle cpus tip-bot for Peter Zijlstra
2014-07-29 14:49 ` [PATCH 1/2] sched: fix and clean up calculate_imbalance Peter Zijlstra
2014-07-29 14:53 ` Peter Zijlstra
2014-07-29 15:26 ` Peter Zijlstra
2014-08-12 14:52 ` [tip:sched/core] sched/fair: Make calculate_imbalance() independent tip-bot for Peter Zijlstra
2014-07-28 18:16 ` [PATCH 2/2] sched: make update_sd_pick_busiest return true on a busier sd riel
2014-07-29 15:27 ` Peter Zijlstra
2014-08-12 14:52 ` [tip:sched/core] sched/fair: Make update_sd_pick_busiest() return 'true' " tip-bot for Rik van Riel
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