Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755025AbaBRM2r (ORCPT ); Tue, 18 Feb 2014 07:28:47 -0500 Received: from mail-oa0-f53.google.com ([209.85.219.53]:63499 "EHLO mail-oa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754280AbaBRM2q convert rfc822-to-8bit (ORCPT ); Tue, 18 Feb 2014 07:28:46 -0500 MIME-Version: 1.0 In-Reply-To: <20140218120522.GG19029@e103034-lin> References: <1392602117-20773-1-git-send-email-alex.shi@linaro.org> <20140218120522.GG19029@e103034-lin> From: Vincent Guittot Date: Tue, 18 Feb 2014 13:28:25 +0100 Message-ID: Subject: Re: [PATCH v2 0/11] remove cpu_load in rq To: Alex Shi Cc: Morten Rasmussen , "mingo@redhat.com" , "peterz@infradead.org" , "daniel.lezcano@linaro.org" , "fweisbec@gmail.com" , "linux@arm.linux.org.uk" , "tony.luck@intel.com" , "fenghua.yu@intel.com" , "james.hogan@imgtec.com" , "jason.low2@hp.com" , "viresh.kumar@linaro.org" , "hanjun.guo@linaro.org" , "linux-kernel@vger.kernel.org" , "tglx@linutronix.de" , "akpm@linux-foundation.org" , "arjan@linux.intel.com" , "pjt@google.com" , "fengguang.wu@intel.com" , "linaro-kernel@lists.linaro.org" , "wangyun@linux.vnet.ibm.com" Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18 February 2014 13:05, Morten Rasmussen wrote: > On Mon, Feb 17, 2014 at 01:55:06AM +0000, Alex Shi wrote: >> The cpu_load decays on time according past cpu load of rq. The sched_avg also decays tasks' load on time. Now we has 2 kind decay for cpu_load. That is a kind of redundancy. And increase the system load by decay calculation. This patch try to remove the cpu_load decay. >> >> There are 5 load_idx used for cpu_load in sched_domain. busy_idx and idle_idx are not zero usually, but newidle_idx, wake_idx and forkexec_idx are all zero on every arch. A shortcut to remove cpu_Load decay in the first patch. just one line patch for this change. >> >> V2, >> 1, This version do some tuning on load bias of target load, to maximum match current code logical. >> 2, Got further to remove the cpu_load in rq. >> 3, Revert the patch 'Limit sd->*_idx range on sysctl' since no needs >> >> Any testing/comments are appreciated. > > Removing cpu_load completely certainly makes things simpler, my worry is > just how much was lost by doing it. I agree that cpu_load needs a > cleanup, but I can't convince myself that just removing it completely > and not having any longer term view of cpu load anymore is without any > negative side-effects. Hi Alex, Have you followed this thread about load_idx and the interest of using them to use different average period ? https://lkml.org/lkml/2014/1/6/499 Vincent > > {source, target}_load() are now instantaneous views of the cpu load, > which means that they may change very frequently. That could potentially > lead to more task migrations at all levels in the domain hierarchy as we > no longer have the more conservative cpu_load[] indexes that were used > at NUMA level. > > Maybe some of the NUMA experts have an opinion about this? > > In the discussions around V1 I think blocked load came up again as a > potential replacement for the current cpu_load array. There are some > issues that need to be solved around blocked_load first though. > > Morten -- 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/