From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754285AbaEEEm6 (ORCPT ); Mon, 5 May 2014 00:42:58 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:47420 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750882AbaEEEm5 (ORCPT ); Mon, 5 May 2014 00:42:57 -0400 Message-ID: <536715C7.9010603@linux.vnet.ibm.com> Date: Mon, 05 May 2014 10:08:31 +0530 From: Preeti U Murthy User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Mike Galbraith CC: Preeti Murthy , Rik van Riel , LKML , Morten Rasmussen , Ingo Molnar , Peter Zijlstra , 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> <1399205073.5180.42.camel@marge.simpson.net> In-Reply-To: <1399205073.5180.42.camel@marge.simpson.net> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14050504-5806-0000-0000-000024CA5E17 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/04/2014 05:34 PM, Mike Galbraith wrote: > On Sun, 2014-05-04 at 17:14 +0530, Preeti Murthy wrote: >> Hi Rik, Mike >> >> On Fri, May 2, 2014 at 12:00 PM, 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... >> >> As far as my understanding goes, the logic in select_task_rq_fair() >> does wake_affine() or calls select_idle_sibling() only at those >> levels of sched domains where the flag SD_WAKE_AFFINE is set. >> This flag is not set at the numa domain and hence they will not be >> balancing across numa nodes. So I don't understand how >> *these functions* are affecting NUMA placements. > > Depends on how far away node yonder is I suppose. > > static inline int sd_local_flags(int level) > { > if (sched_domains_numa_distance[level] > RECLAIM_DISTANCE) > return 0; > > return SD_BALANCE_EXEC | SD_BALANCE_FORK | SD_WAKE_AFFINE; > } > > Hmm thanks Mike, I totally missed this! Regards Preeti U Murthy