Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754609Ab3HMISJ (ORCPT ); Tue, 13 Aug 2013 04:18:09 -0400 Received: from mail-lb0-f170.google.com ([209.85.217.170]:43076 "EHLO mail-lb0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753301Ab3HMISG (ORCPT ); Tue, 13 Aug 2013 04:18:06 -0400 MIME-Version: 1.0 In-Reply-To: References: <20130812144309.GK27162@twins.programming.kicks-ass.net> <20130813073842.GP27162@twins.programming.kicks-ass.net> Date: Tue, 13 Aug 2013 16:18:04 +0800 Message-ID: Subject: Re: false nr_running check in load balance? From: Lei Wen To: Paul Turner Cc: Peter Zijlstra , LKML , Ingo Molnar , Lei Wen Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1382 Lines: 41 Hi Paul, On Tue, Aug 13, 2013 at 4:08 PM, Paul Turner wrote: > On Tue, Aug 13, 2013 at 12:38 AM, Peter Zijlstra wrote: >> On Tue, Aug 13, 2013 at 12:45:12PM +0800, Lei Wen wrote: >>> > Not quite right; I think you need busiest->cfs.h_nr_running. >>> > cfs.nr_running is the number of entries running in this 'group'. If >>> > you've got nested groups like: >>> > >>> > 'root' >>> > \ >>> > 'A' >>> > / \ >>> > t1 t2 >>> > >>> > root.nr_running := 1 'A', even though you've got multiple running tasks. >>> > >>> >>> You're absolutely right for this. :) >>> I miss it for not considering the group case... >>> >>> Then do you think it is necessary to do below change in load_balance() code? >>> - if (busiest->nr_running > 1) { >>> + if (busiest->cfs.h_nr_running > 1) { >>> >> >> Yes I think that would be fine. > > If we pivot to use h_nr_running we should probably also update > call-sites such as cpu_load_avg_per_task() for consistency. I didn't find cpu_load_avg_per_task in the latest linux git... Is it a new patch pending while not being submitted? Thanks, Lei -- 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/