From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751805AbaEBK4u (ORCPT ); Fri, 2 May 2014 06:56:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52834 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751353AbaEBK4t (ORCPT ); Fri, 2 May 2014 06:56:49 -0400 Message-ID: <536379D0.8070306@redhat.com> Date: Fri, 02 May 2014 06:56:16 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Mike Galbraith CC: linux-kernel@vger.kernel.org, morten.rasmussen@arm.com, mingo@kernel.org, peterz@infradead.org, george.mccollister@gmail.com, ktkhai@parallels.com Subject: Re: [PATCH RFC/TEST] sched: make sync affine wakeups work References: <20140502004237.79dd3de6@annuminas.surriel.com> <1399011219.5233.55.camel@marge.simpson.net> <53633B81.1080403@redhat.com> <1399016273.5233.94.camel@marge.simpson.net> In-Reply-To: <1399016273.5233.94.camel@marge.simpson.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/02/2014 03:37 AM, Mike Galbraith wrote: > On Fri, 2014-05-02 at 02:30 -0400, Rik van Riel wrote: >> On 05/02/2014 02:13 AM, Mike Galbraith wrote: >>> On Fri, 2014-05-02 at 00:42 -0400, Rik van Riel wrote: >>> >>>> Whether or not this is the right thing to do remains to be seen, >>>> but it does allow us to verify whether or not the wake_affine >>>> strategy of always doing affine wakeups and only disabling them >>>> in a specific circumstance is sound, or needs rethinking... >>> >>> Yes, it needs rethinking. >>> >>> I know why you want to try this, yes, select_idle_sibling() is very much >>> a two faced little bitch. >> >> My biggest problem with select_idle_sibling and wake_affine in >> general is that it will override NUMA placement, even when >> processes only wake each other up infrequently... > > Hm, seems the thing to do would be to tell select_task_rq_fair() to keep > it's mitts off of tasks that the numasched stuff has placed rather than > decapitating select_idle_sibling() or some other drastic measure. Thing is, if tasks are waking each other up frequently enough, we probably DO want to place them near each other with select_idle_sibling. We just cannot afford to have it as the default behaviour for casual wakeup activity, because it will mess up other things. -- All rights reversed