From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754031AbbIHIp4 (ORCPT ); Tue, 8 Sep 2015 04:45:56 -0400 Received: from blu004-omc1s27.hotmail.com ([65.55.116.38]:59525 "EHLO BLU004-OMC1S27.hotmail.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752232AbbIHIpx (ORCPT ); Tue, 8 Sep 2015 04:45:53 -0400 X-TMN: [2KLejVczUaus7Lhx8QlAqkb0SqbsKf7s] X-Originating-Email: [wanpeng.li@hotmail.com] Message-ID: Subject: Re: [PATCH] sched: fix lose fair sleeper bonus in switch_to_fair() To: Byungchul Park References: <20150908052817.GD6455@byungchulpark-X58A-UD3R> <20150908061426.GE6455@byungchulpark-X58A-UD3R> <20150908063240.GF6455@byungchulpark-X58A-UD3R> <20150908071139.GI6455@byungchulpark-X58A-UD3R> <20150908075728.GJ6455@byungchulpark-X58A-UD3R> <20150908082239.GK6455@byungchulpark-X58A-UD3R> CC: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, yuyang.du@intel.com From: Wanpeng Li Date: Tue, 8 Sep 2015 16:45:46 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 08 Sep 2015 08:45:50.0934 (UTC) FILETIME=[C3D17760:01D0EA12] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/8/15 4:38 PM, Wanpeng Li wrote: > On 9/8/15 4:22 PM, Byungchul Park wrote: >> On Tue, Sep 08, 2015 at 04:04:49PM +0800, Wanpeng Li wrote: >>>>> However, if se->vruntime -= cfs_rq->min_vruntime is positive, the >>>>> behavior is different after your patch. e.g. se->vruntime(the >>>>> relative vruntime in switched_to_fair()) < min_vruntime - >>>>> sysctl_sched_latency/2 >>>>> >>>>> before your patch: >>>>> >>>>> se->vruntime = min_vruntime - sysctl_sched_latency/2 (place_entity()) >>>> my patch is based on ff277d4 commit at tip/sched/core. >>>> >>>> there's no change between before and after. >>>> >>>> check it please. >>>> >>>> and this logic seems to be no problem to me. :( >>> Your logic will lose fair sleeper bonus in the scenario which I >>> pointed out. >> i mean in ff277d4 commit: > > Please include the commit subject when you point out a commit, do you > mean this one? > > commit ff277d4250fe715b6666219b1a3423b863418794 > Author: Andrea Parri > Date: Wed Aug 5 15:56:19 2015 +0200 > > sched/deadline: Fix comment in enqueue_task_dl() > > The "dl_boosted" flag is set by comparing *absolute* deadlines > (c.f., rt_mutex_setprio()). > > > What's the relationship w/ this patch? I think you mean your commit: commit 7855a35ac07a350e2cd26f09568a6d8e372be358 Author: Byungchul Park Date: Mon Aug 10 18:02:55 2015 +0900 sched: Ensure a task has a non-normalized vruntime when returning back to CFS However, that is wrong in the scenario which I mentioned. Regards, Wanpeng Li