From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751228AbWGDVo2 (ORCPT ); Tue, 4 Jul 2006 17:44:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751250AbWGDVo2 (ORCPT ); Tue, 4 Jul 2006 17:44:28 -0400 Received: from mx1.suse.de ([195.135.220.2]:49077 "EHLO mx1.suse.de") by vger.kernel.org with ESMTP id S1751228AbWGDVo2 (ORCPT ); Tue, 4 Jul 2006 17:44:28 -0400 From: Andi Kleen To: Chuck Ebbert <76306.1226@compuserve.com> Subject: Re: [PATCH 2/2] i386 TIF flags for debug regs and io bitmap in ctxsw Date: Tue, 4 Jul 2006 23:47:00 +0200 User-Agent: KMail/1.9.1 Cc: Stephane Eranian , Andrew Morton , linux-kernel References: <200607041719_MC3-1-C420-EC5A@compuserve.com> In-Reply-To: <200607041719_MC3-1-C420-EC5A@compuserve.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200607042347.00598.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 04 July 2006 23:19, Chuck Ebbert wrote: > In-Reply-To: <20060704072939.GC5902@frankl.hpl.hp.com> > > On Tue, 4 Jul 2006 00:29:39 -0700, Stephane Eranian wrote: > > Following my discussion with Andi. Here is a patch that introduces > > two new TIF flags to simplify the context switch code in __switch_to(). > > The idea is to minimize the number of cache lines accessed in the common > > case, i.e., when neither the debug registers nor the I/O bitmap are used. > > 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. -Andi