From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763378AbZAQQBv (ORCPT ); Sat, 17 Jan 2009 11:01:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756288AbZAQQBl (ORCPT ); Sat, 17 Jan 2009 11:01:41 -0500 Received: from mx3.mail.elte.hu ([157.181.1.138]:55170 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754265AbZAQQBk (ORCPT ); Sat, 17 Jan 2009 11:01:40 -0500 Date: Sat, 17 Jan 2009 17:01:15 +0100 From: Ingo Molnar To: Mike Galbraith , Avi Kivity , Kevin Shanahan Cc: Andrew Morton , a.p.zijlstra@chello.nl, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [git pull] scheduler fixes Message-ID: <20090117160115.GA31601@elte.hu> References: <1231964647.14825.59.camel@laptop> <20090116204049.f4d6ef1c.akpm@linux-foundation.org> <1232173776.7073.21.camel@marge.simson.net> <1232186054.6813.48.camel@marge.simson.net> <1232186877.14073.59.camel@laptop> <1232188484.6813.85.camel@marge.simson.net> <1232193617.14073.67.camel@laptop> <1232194752.6273.5.camel@marge.simson.net> <20090117044316.bda7d0bd.akpm@linux-foundation.org> <1232198574.16303.8.camel@marge.simson.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1232198574.16303.8.camel@marge.simson.net> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Mike Galbraith wrote: > On Sat, 2009-01-17 at 04:43 -0800, Andrew Morton wrote: > > http://bugzilla.kernel.org/show_bug.cgi?id=12465 just popped up - another > > scheduler regression. It has been bisected. > > Seems pretty clear. I'd suggest reverting it. We can revert it (and will revert it if no solution is found), but i'd also like to understand why it happens, because that kind of regression from this change is unexpected - we might be hiding some bug that could pop up under less debuggable circumstances, so we need to understand it while we have a chance. Below is the commit in question. Avi, any ideas what makes KVM special here? Perhaps its use of "preempt notifiers" is causing a problem somehow? Ingo --------------> >>From 14800984706bf6936bbec5187f736e928be5c218 Mon Sep 17 00:00:00 2001 From: Mike Galbraith Date: Fri, 7 Nov 2008 15:26:50 +0100 Subject: [PATCH] sched: fine-tune SD_MC_INIT Tune SD_MC_INIT the same way as SD_CPU_INIT: unset SD_BALANCE_NEWIDLE, and set SD_WAKE_BALANCE. This improves vmark by 5%: vmark 132102 125968 125497 messages/sec avg 127855.66 .984 vmark 139404 131719 131272 messages/sec avg 134131.66 1.033 Signed-off-by: Mike Galbraith Acked-by: Peter Zijlstra Signed-off-by: Ingo Molnar # *DOCUMENTATION* --- include/linux/topology.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/include/linux/topology.h b/include/linux/topology.h index 34a7ee0..a8d8405 100644 --- a/include/linux/topology.h +++ b/include/linux/topology.h @@ -120,10 +120,10 @@ void arch_update_cpu_topology(void); .wake_idx = 1, \ .forkexec_idx = 1, \ .flags = SD_LOAD_BALANCE \ - | SD_BALANCE_NEWIDLE \ | SD_BALANCE_FORK \ | SD_BALANCE_EXEC \ | SD_WAKE_AFFINE \ + | SD_WAKE_BALANCE \ | SD_SHARE_PKG_RESOURCES\ | BALANCE_FOR_MC_POWER, \ .last_balance = jiffies, \