From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750944AbWKBRhF (ORCPT ); Thu, 2 Nov 2006 12:37:05 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750957AbWKBRhF (ORCPT ); Thu, 2 Nov 2006 12:37:05 -0500 Received: from mga05.intel.com ([192.55.52.89]:42595 "EHLO fmsmga101.fm.intel.com") by vger.kernel.org with ESMTP id S1750944AbWKBRhD (ORCPT ); Thu, 2 Nov 2006 12:37:03 -0500 X-ExtLoop1: 1 X-IronPort-AV: i="4.09,381,1157353200"; d="scan'208"; a="156681137:sNHT947449321" Subject: 2.6.19-rc1: Slowdown in lmbench's fork From: Tim Chen Reply-To: tim.c.chen@linux.intel.com To: linux-kernel@vger.kernel.org Cc: ebiederm@xmission.com Content-Type: text/plain Organization: Intel Date: Thu, 02 Nov 2006 08:44:57 -0800 Message-Id: <1162485897.10806.72.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.0.2 (2.0.2-8) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org After introduction of the following patch: [PATCH] genirq: x86_64 irq: make vector_irq per cpu http://kernel.org/git/? p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=550f2299ac8ffaba943cf211380d3a8d3fa75301 we see fork benchmark in lmbench-3.0-a7 slowed by 11.5% on a 2 socket woodcrest machine. Similar change is seen also on other SMP Xeon machines. When running lmbench, we have chosen the lmbench option to pin parent and child on different processor cores Overhead of calling sched_setaffinity to place the process on processor is included in lmbench's fork time measurement. The patch may play a role in increasing this. The two follow up patches to the original "make vector_irq per cpu" did not affect the fork time. [PATCH] x86_64 irq: Properly update vector_irq [PATCH] x86-64: Only look at per_cpu data for online ... Tim