Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751988Ab3FXPiJ (ORCPT ); Mon, 24 Jun 2013 11:38:09 -0400 Received: from mga01.intel.com ([192.55.52.88]:42757 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750939Ab3FXPiI (ORCPT ); Mon, 24 Jun 2013 11:38:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.87,929,1363158000"; d="scan'208";a="354918750" Message-ID: <51C867CF.70908@intel.com> Date: Mon, 24 Jun 2013 23:37:51 +0800 From: Alex Shi User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120912 Thunderbird/15.0.1 MIME-Version: 1.0 To: Paul Turner CC: Ingo Molnar , Peter Zijlstra , Thomas Gleixner , Andrew Morton , Arjan van de Ven , Borislav Petkov , Namhyung Kim , Mike Galbraith , Morten Rasmussen , Vincent Guittot , gregkh@linuxfoundation.org, Preeti U Murthy , Viresh Kumar , LKML , len.brown@intel.com, rafael.j.wysocki@intel.com, jkosina@suse.cz, Clark Williams , tony.luck@intel.com, keescook@chromium.org, Mel Gorman , Rik van Riel Subject: Re: [Resend patch v8 0/13] use runnable load in schedule balance References: <1371694737-29336-1-git-send-email-alex.shi@intel.com> <51C7B9B8.6090309@intel.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2648 Lines: 59 On 06/24/2013 06:40 PM, Paul Turner wrote: >> > Ingo & Peter, >> > >> > This patchset was discussed spread and deeply. >> > >> > Now just 6th/8th patch has some arguments on them, Paul think it is >> > better to consider blocked_load_avg in balance, since it is helpful on >> > some scenarios, but I think on most of scenarios, the blocked_load_avg >> > just cause load imbalance among cpus. and plus testing show with >> > blocked_load_avg the performance is just worse on some benchmarks. So, I >> > still prefer to keep it out of balance. > I think you have perhaps misunderstood what I was trying to explain. > > I have no problems with not including blocked load in load-balance, in > fact, I encouraged not accumulating it in an average of averages in > CPU load. > Many thanks for re-clarification! > The problem is that your current approach has removed it both from > load-balance _and_ from shares distribution; isolation matters as much > as performance in the cgroup case (otherwise you would just not use > cgroups). I would expect the latter to have quite negative effects on > fairness, this is my primary concern. > So the argument is just on patch 'sched/tg: remove blocked_load_avg in balance'. :) I understand your correctness concern. but blocked_load_avg still will be decayed to zero in few hundreds ms. So such correctness needs just in few hundreds ms. (and cause performance drop) The blocked_load_avg is decayed on same degree as runnable load, it is a bit overweight since task slept. since it may will be waken up on other cpu. So to relieve this overweight, could we use the half or a quarter weight of blocked_load_avg? like following: diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ddbc19f..395f57c 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1358,7 +1358,7 @@ static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, struct task_group *tg = cfs_rq->tg; s64 tg_contrib; - tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg; + tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg / 2; tg_contrib -= cfs_rq->tg_load_contrib; if (force_update || abs64(tg_contrib) > cfs_rq->tg_load_contrib / 8) { >> > >> > http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg455196.html >> > >> > Is it the time to do the decision or give more comments? Thanks! -- Thanks Alex -- 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/