Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754711AbaGCDvI (ORCPT ); Wed, 2 Jul 2014 23:51:08 -0400 Received: from mail-we0-f181.google.com ([74.125.82.181]:44302 "EHLO mail-we0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750916AbaGCDvH (ORCPT ); Wed, 2 Jul 2014 23:51:07 -0400 Message-ID: <1404359462.5137.72.camel@marge.simpson.net> Subject: Re: [PATCH] sched: select 'idle' cfs_rq per task-group to prevent tg-internal imbalance From: Mike Galbraith To: Rik van Riel Cc: Michael wang , Peter Zijlstra , Ingo Molnar , Alex Shi , Paul Turner , Mel Gorman , Daniel Lezcano , LKML Date: Thu, 03 Jul 2014 05:51:02 +0200 In-Reply-To: <53B41B7E.8020009@redhat.com> References: <53A11A89.5000602@linux.vnet.ibm.com> <20140623094251.GS19860@laptop.programming.kicks-ass.net> <53A8F1DE.2060908@linux.vnet.ibm.com> <20140701082020.GL6758@twins.programming.kicks-ass.net> <53B273A2.5050500@linux.vnet.ibm.com> <53B41B7E.8020009@redhat.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3 Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2014-07-02 at 10:47 -0400, Rik van Riel wrote: > On 07/01/2014 04:38 AM, Michael wang wrote: > > On 07/01/2014 04:20 PM, Peter Zijlstra wrote: > > [snip] > >>> > >>> Just wondering could we make this another scheduler feature? > >> > >> No; sched_feat() is for debugging, BIG CLUE: its guarded by > >> CONFIG_SCHED_DEBUG, anybody using it in production or anywhere else is > >> broken. > >> > >> If people are using it, I should remove or at least randomize the > >> interface. > > > > Fair enough... but is there any suggestions on how to handle this issue? > > > > Currently when dbench running with stress, it could only gain one CPU, > > and cpu-cgroup cpu.shares is meaningless, is there any good methods to > > address that? > > select_idle_sibling will iterate over all of the CPUs > in an LLC domain if there is no idle cpu in the domain. > > I suspect it would not take much extra code to track > down the idlest CPU in the LLC domain, and make sure to > schedule tasks there, in case no completely idle CPU > was found. > > Are there any major problems with that thinking? That's full wake balance.. if that was cheap, select_idle_sibling() would not exist. -Mike -- 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/