Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752152Ab3EBFsy (ORCPT ); Thu, 2 May 2013 01:48:54 -0400 Received: from e23smtp02.au.ibm.com ([202.81.31.144]:34826 "EHLO e23smtp02.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751834Ab3EBFsx (ORCPT ); Thu, 2 May 2013 01:48:53 -0400 Message-ID: <5181FE1B.6010508@linux.vnet.ibm.com> Date: Thu, 02 May 2013 13:48:11 +0800 From: Michael Wang User-Agent: Mozilla/5.0 (X11; Linux i686; rv:16.0) Gecko/20121011 Thunderbird/16.0.1 MIME-Version: 1.0 To: Peter Zijlstra CC: LKML , Ingo Molnar , Mike Galbraith , Alex Shi , Namhyung Kim , Paul Turner , Andrew Morton , "Nikunj A. Dadhania" , Ram Pai Subject: Re: [PATCH] sched: wake-affine throttle References: <5164DCE7.8080906@linux.vnet.ibm.com> <1366626208.2721.12.camel@laptop> In-Reply-To: <1366626208.2721.12.camel@laptop> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13050205-5490-0000-0000-00000361A60F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1847 Lines: 55 On 04/22/2013 06:23 PM, Peter Zijlstra wrote: > > OK,.. Ingo said that pipe-test was the original motivation for > wake_affine() and since that's currently broken to pieces due to > select_idle_sibling() is there still a benefit to having it at all? > > Can anybody find any significant regression when simply killing > wake_affine()? I got the proof that we could not simply killing the stuff (finally...). It's the hackbench with a high pipe number, still on 12 cpu box, the result of "./hackbench 48 process 10000" is: Running with 48*40 (== 1920) tasks. Time: 33.372 After killed the wake-affine, the result is: Running with 48*40 (== 1920) tasks. Time: 38.205 About 14.48% performance dropped without wake-affine, I guess it was caused by the missing spread behaviour. I've done the test for several times, also compared with the throttle approach, default 1ms interval still works very well, the regression on hackbench start to exceed 2% when interval become 100ms on my box, but please note the pgbench already gain a lot benefit at that time. I think now we could say that wake-affine is useful, and we could not simply kill it. So I still suggest we adopt the throttle approach, then we could make adjustment according to the demand. And please let me know if there are any concerns ;-) Regards, Michael Wang > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/