From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964825AbWGELtp (ORCPT ); Wed, 5 Jul 2006 07:49:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S964826AbWGELtp (ORCPT ); Wed, 5 Jul 2006 07:49:45 -0400 Received: from liaag2af.mx.compuserve.com ([149.174.40.157]:60609 "EHLO liaag2af.mx.compuserve.com") by vger.kernel.org with ESMTP id S964825AbWGELto (ORCPT ); Wed, 5 Jul 2006 07:49:44 -0400 Date: Wed, 5 Jul 2006 07:44:52 -0400 From: Chuck Ebbert <76306.1226@compuserve.com> Subject: Re: [PATCH 2/2] i386 TIF flags for debug regs and io bitmap in ctxsw To: Andi Kleen Cc: linux-kernel , Andrew Morton , Stephane Eranian Message-ID: <200607050745_MC3-1-C42B-9936@compuserve.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org In-Reply-To: <200607042347.00598.ak@suse.de> On Tue, 4 Jul 2006 23:47:00 +0200, Andi Kleen wrote: > > I get a 5-10% speedup in task switch times with this patch. > > That sounds too much. How did you measure it? > > Note that lmbench tends to be unstable for this. I used lmbench's lat_ctx(8). According to its manpage, you can make multiple runs and use the minimum, not the average. And the gain may have been high because I tested on an old PII notebook with small cache and slow memory. -- Chuck "You can't read a newspaper if you can't read." --George W. Bush