linux-kernel - Re: [PATCH?] Livelock in pick_next_task_fair() / idle

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Message-ID: <1435765657.2863.14.camel@gmail.com>
Date:	Wed, 01 Jul 2015 17:47:37 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Rabin Vincent <rabin.vincent@...s.com>
Cc:	"mingo@...hat.com" <mingo@...hat.com>,
	"peterz@...radead.org" <peterz@...radead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH?] Livelock in pick_next_task_fair() / idle_balance()

On Wed, 2015-07-01 at 16:55 +0200, Rabin Vincent wrote:

> So, we will not hit the "if (env->src_rq->load.weight <=
> env->dst_rq->load.weight + d_load)" condition to break out of the loop until we
> actualy move all tasks.  So the patch will not have any effect on this case.
> Or am I missing something?

Probably not.  I did have it breaking if dst_rq would pass
src_rq->nr_running, which would certainly stop it, but thought I try to
let it watch weights.

Either way, task_h_load(p) returning 0 is not very wonderful.

	-Mike

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