From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933407AbYGQVng (ORCPT ); Thu, 17 Jul 2008 17:43:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756709AbYGQVn2 (ORCPT ); Thu, 17 Jul 2008 17:43:28 -0400 Received: from smtp-out04.alice-dsl.net ([88.44.63.6]:13514 "EHLO smtp-out04.alice-dsl.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754793AbYGQVn1 (ORCPT ); Thu, 17 Jul 2008 17:43:27 -0400 To: Jeremy Fitzhardinge Cc: "Alex Nixon (Intern)" , Peter Zijlstra , Ingo Molnar , Linux Kernel Mailing List , Ian Campbell Subject: Re: Large increase in context switch rate From: Andi Kleen References: <487E43D9.7080703@goop.org> <1216286250.5232.67.camel@twins> <487F5F15.4050208@goop.org> <0E902970173AF84089673FA54B7FE78A32906B@lonpexch01.citrite.net> <487F6913.2000602@goop.org> <0E902970173AF84089673FA54B7FE78A32906C@lonpexch01.citrite.net> <487F6F1F.2030808@goop.org> Date: Thu, 17 Jul 2008 23:43:24 +0200 In-Reply-To: <487F6F1F.2030808@goop.org> (Jeremy Fitzhardinge's message of "Thu, 17 Jul 2008 09:11:11 -0700") Message-ID: <87mykgrxtv.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 17 Jul 2008 21:43:23.0304 (UTC) FILETIME=[230E7280:01C8E856] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge writes: > > OK, but that still doesn't account for the relatively large increase > from 2.6.18 -> 2.6.26. You're using HZ=100 in both cases, I presume. > > The other variable is NOHZ and highres timers. You could try turning > those off in 2.6.26. Also, CONFIG_PREEMPT could well make a > difference. 2.6.18-xen doesn't support CONFIG_PREEMPT at all, but > pvops(-xen) does. If it's that easily reproducible you could just bisect it? -Andi