Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965692Ab2EXVpZ (ORCPT ); Thu, 24 May 2012 17:45:25 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:52197 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758046Ab2EXVpW convert rfc822-to-8bit (ORCPT ); Thu, 24 May 2012 17:45:22 -0400 Date: Thu, 24 May 2012 16:45:17 -0500 From: Jonathan Nieder To: Anders =?utf-8?Q?Bostr=C3=B6m?= Cc: linux-kernel@vger.kernel.org, =?utf-8?B?TGVzxYJhdyBLb3BlxIc=?= , Aman Gupta , Doug Smythies , Peter Zijlstra , Thomas Gleixner Subject: Re: [3.2.16 -> 3.2.17 regression] High reported CPU load when idle Message-ID: <20120524214516.GB1158@burratino> References: <20120523.144057.899060240318474097.anders@netinsight.net> <20120523215359.GA19798@burratino> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <20120523215359.GA19798@burratino> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1303 Lines: 35 (cc-ing Peter and Thomas because there is a nice graph) > Anders Boström wrote[1]: >> Starting with 3.2.17-1, the CPU load accounting is broken when the >> computer is idle. The CPU load is reported as >0.50 when >> idle. 3.2.16-1 don't suffer from this problem. >> >> Suspected patch is the upstream patch >> "sched: Fix nohz load accounting -- again!" >> commit 5e2d50da11f0e6ec3ce8fe658d7c83b0b4346c68 to 3.2 and >> originating from c308b56b5398779cd3da0f62ab26b0453494c3d4 . >> >> See also: >> >> https://bugs.launchpad.net/unity/+bug/991370 >> https://lkml.org/lkml/2012/5/22/310 >> https://bugzilla.redhat.com/show_bug.cgi?id=822877 >> https://bbs.archlinux.org/viewtopic.php?id=141289 I just found [1] from [2] which seems to describe the symptoms pretty well. Peter, Thomas, advice? Anders et al: does 556061b00c9f ("sched/nohz: Fix rq->cpu_load[] calculations", 2012-05-11) change anything? Thanks, Jonathan [1] https://launchpadlibrarian.net/105809696/commit_low_load_rev2.png [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/838811 -- 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/