From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932253AbbE1O2I (ORCPT ); Thu, 28 May 2015 10:28:08 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:52766 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932226AbbE1O16 (ORCPT ); Thu, 28 May 2015 10:27:58 -0400 Message-ID: <556725CA.6070103@fb.com> Date: Thu, 28 May 2015 10:27:22 -0400 From: Josef Bacik User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Peter Zijlstra CC: , , , , Subject: Re: [PATCH RESEND] sched: prefer an idle cpu vs an idle sibling for BALANCE_WAKE References: <1432761736-22093-1-git-send-email-jbacik@fb.com> <20150528102127.GD3644@twins.programming.kicks-ass.net> <20150528110514.GR18673@twins.programming.kicks-ass.net> In-Reply-To: <20150528110514.GR18673@twins.programming.kicks-ass.net> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.52.123] X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.14.151,1.0.33,0.0.0000 definitions=2015-05-28_04:2015-05-28,2015-05-28,1970-01-01 signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/28/2015 07:05 AM, Peter Zijlstra wrote: > > So maybe you want something like the below; that cures the thing Morten > raised, and we continue looking for sd, even after we found affine_sd. > > It also avoids the pointless idle_cpu() check Mike raised by making > select_idle_sibling() return -1 if it doesn't find anything. > > Then it continues doing the full balance IFF sd was set, which is keyed > off of sd->flags. > > And note (as Mike already said), BALANCE_WAKE does _NOT_ look for idle > CPUs, it looks for the least loaded CPU. And its damn expensive. > Sorry I was just assuming based on the commit message when WAKE_IDLE was removed, this isn't my area. > > Rewriting this entire thing is somewhere on the todo list :/ Thanks I'm building and deploying this so I can run our perf test, I'll have results in ~3 hours. Josef