From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752995Ab0IPDpR (ORCPT ); Wed, 15 Sep 2010 23:45:17 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:60654 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1752386Ab0IPDpP (ORCPT ); Wed, 15 Sep 2010 23:45:15 -0400 X-Authenticated: #14349625 X-Provags-ID: V01U2FsdGVkX19jtUE2R89jXarxjR1kIaNXYZHzElaoG4F+YI4DF7 lWbBeka9bvWoCw Subject: Re: 2.6.32.y stable kernel regression with taskset From: Mike Galbraith To: Yinghai Lu Cc: Greg KH , Ingo Molnar , Peter Zijlstra , "linux-kernel@vger.kernel.org" , John Wright In-Reply-To: <4C9114A6.6040500@oracle.com> References: <4C9114A6.6040500@oracle.com> Content-Type: text/plain Date: Thu, 16 Sep 2010 05:45:12 +0200 Message-Id: <1284608712.7403.10.camel@marge.simson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.24.1.1 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2010-09-15 at 11:47 -0700, Yinghai Lu wrote: > found problem with cpuscaling test. > > Under 2.6.32.21 Userspace gov > min freq load test time is nearly the same as max freq load test time around ~16 seconds > > under 2.6.18-194 > min freq load test time is ~40 seconds > max freq load test time is ~ 17 seconds > > the test is > 1. set governor for one cpu to userspace > 2. set freq to min for that cpu > 3. using taskset to put load test only on that cpu, and get the time for load test. > > so that mean taskset did not put load test on cpu that we want. and other cpu still have ondemand governor and load test get done much faster > > git bisect report: > > c6fc81afa2d7ef2f775e48672693d8a0a8a7325d is the first bad commit > commit c6fc81afa2d7ef2f775e48672693d8a0a8a7325d > Author: John Wright > Date: Tue Apr 13 16:55:37 2010 -0600 > > sched: Fix a race between ttwu() and migrate_task() Known issue. There's a sched series for 32-stable in the pipeline. -Mike