From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752013Ab3AaG6n (ORCPT ); Thu, 31 Jan 2013 01:58:43 -0500 Received: from LGEMRELSE7Q.lge.com ([156.147.1.151]:60965 "EHLO LGEMRELSE7Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751479Ab3AaG6l (ORCPT ); Thu, 31 Jan 2013 01:58:41 -0500 X-AuditID: 9c930197-b7ca4ae000006ba8-d6-510a161fb520 From: Namhyung Kim To: Michael Wang Cc: Sebastian Andrzej Siewior , linux-kernel@vger.kernel.org, "Rafael J. Wysocki" , Ingo Molnar , Peter Zijlstra , tglx@linutronix.de Subject: Re: [RFC 2/2] sched/fair: prefer a CPU in the "lowest" idle state References: <1359580757-4121-1-git-send-email-bigeasy@linutronix.de> <1359580757-4121-3-git-send-email-bigeasy@linutronix.de> <5109D313.1020409@linux.vnet.ibm.com> <8738xiue31.fsf@sejong.aot.lge.com> <510A1198.2070803@linux.vnet.ibm.com> Date: Thu, 31 Jan 2013 15:58:38 +0900 In-Reply-To: <510A1198.2070803@linux.vnet.ibm.com> (Michael Wang's message of "Thu, 31 Jan 2013 14:39:20 +0800") Message-ID: <87txpxu9cx.fsf@sejong.aot.lge.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 31 Jan 2013 14:39:20 +0800, Michael Wang wrote: > On 01/31/2013 01:16 PM, Namhyung Kim wrote: >> Anyway, I have an idea with this in mind. It's like adding a new "idle >> load" to each idle cpu rather than special casing the idle cpus like >> above. IOW an idle cpu will get very small load weight depends on how >> deep it's slept so that it can be compared to other cpus in a same way >> but we can find prefered (lowest load) cpu among the idle cpus. >> >> The simple way I can think of is adding idle_level to a rq load in >> weighted_cpuload(): >> >> static unsigned long weighted_cpuload(const int cpu) >> { >> return cpu_rq(cpu)->load.weight + cpuidle_get_state(cpu); >> } > > Hmm... then we don't need changes in find_idlest_cpu(), just compare the > load as before, but it works only when the appendix state value is > smaller than the lowest load of one task, which is 15 currently, I'm not > sure whether we have the promise... You said about a nice 19 process, right? But I found that SCHED_IDLE task will have weight of 3. :( #define WEIGHT_IDLEPRIO 3 But AFAIK the number of states in cpuidle is usually less than 10 so maybe we can change the weight then, but there's no promise... Thanks, Namhyung