From: Peter Zijlstra <peterz@infradead.org>
To: Uladzislau Rezki <urezki@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Uladzislau 2 Rezki <uladzislau2.rezki@sonymobile.com>
Subject: Re: [RFC,v2 1/3] sched: set loop_max after rq lock is taken
Date: Thu, 9 Feb 2017 13:14:58 +0100 [thread overview]
Message-ID: <20170209121458.GC6500@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1486543409-11493-1-git-send-email-urezki@gmail.com>
On Wed, Feb 08, 2017 at 09:43:27AM +0100, Uladzislau Rezki wrote:
> From: Uladzislau 2 Rezki <uladzislau2.rezki@sonymobile.com>
>
> While doing a load balance there is a race in setting
> loop_max variable since nr_running can be changed causing
> incorect iteration loops.
>
> As a result we may skip some candidates or check the same
> tasks again.
When doing the actual migration we'll drop this lock again and
nr_running can change again.
This cannot be done perfectly, all of load-balancing is riddled with
races like this, nobody cares.
prev parent reply other threads:[~2017-02-09 13:35 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-08 8:43 [RFC,v2 1/3] sched: set loop_max after rq lock is taken Uladzislau Rezki
2017-02-08 8:43 ` [RFC,v2 2/3] sched: set number of iterations to h_nr_running Uladzislau Rezki
2017-02-09 12:20 ` Peter Zijlstra
2017-02-09 18:59 ` Uladzislau Rezki
2017-02-08 8:43 ` [RFC,v2 3/3] sched: ignore task_h_load for CPU_NEWLY_IDLE Uladzislau Rezki
2017-02-08 9:19 ` Mike Galbraith
2017-02-09 10:12 ` Uladzislau Rezki
2017-02-09 12:22 ` Peter Zijlstra
2017-02-09 18:54 ` Uladzislau Rezki
2017-02-13 13:51 ` Peter Zijlstra
2017-02-13 17:17 ` Uladzislau Rezki
2017-02-14 18:28 ` Uladzislau Rezki
2017-02-15 18:58 ` Dietmar Eggemann
2017-02-16 11:20 ` Uladzislau Rezki
2017-03-08 15:35 ` Uladzislau Rezki
2017-02-09 12:14 ` Peter Zijlstra [this message]
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