From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992968AbXDDPn6 (ORCPT ); Wed, 4 Apr 2007 11:43:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992974AbXDDPn6 (ORCPT ); Wed, 4 Apr 2007 11:43:58 -0400 Received: from gw.goop.org ([64.81.55.164]:59878 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992968AbXDDPn5 (ORCPT ); Wed, 4 Apr 2007 11:43:57 -0400 Message-ID: <4613C7AB.5020509@goop.org> Date: Wed, 04 Apr 2007 08:43:39 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 1.5.0.10 (X11/20070302) MIME-Version: 1.0 To: Ingo Molnar CC: Andi Kleen , Andrew Morton , Linus Torvalds , lkml Subject: Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries References: <20070402055652.610711908@goop.org> <20070402055704.278590661@goop.org> <200704020812.18320.ak@suse.de> <46136F25.7030907@goop.org> <20070404095745.GA16726@elte.hu> In-Reply-To: <20070404095745.GA16726@elte.hu> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > the main metric we are interested in is the overhead for people who just > want to run the non-patched native kernel that has CONFIG_PARAVIRT > enabled (99%+ of the users at the moment), so the delta is: > > null: +12.0% > null IO: +7.5% > stat: within noise > open/close: within noise > TCP: ~5.0% > signal install: 2.0% > signal handle: 4.7% > fork: 2.7% > exec: 3.6% > shell: 3.6% > Hm, I don't think you can get this much precision out of these numbers. I noticed larger variations from boot-to-boot running the same test. > this is not 'barely measurable' but 'BLOODY LARGE' overhead. Yes. Fortunately there's a noticable difference between native and unpatched paravirt, because it shows all the effort we put into patching is worthwhile. >> paravirt, patching >> ezr Linux 2.6.21- 1000 0.25 0.53 31.8 34.4 10.1 1.04 5.44 730. 1583 4600 >> ezr Linux 2.6.21- 1000 0.26 0.55 32.1 35.2 13.3 1.03 5.48 748. 1589 4606 >> ezr Linux 2.6.21- 1000 0.26 0.54 32.0 34.9 14.1 1.04 5.43 752. 1606 4647 >> > > i guess this pretty much makes the case for patching ... > Right, that's why there's patching. J