From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932074AbXDDPsK (ORCPT ); Wed, 4 Apr 2007 11:48:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933566AbXDDPsK (ORCPT ); Wed, 4 Apr 2007 11:48:10 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:47218 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932074AbXDDPsJ (ORCPT ); Wed, 4 Apr 2007 11:48:09 -0400 Date: Wed, 4 Apr 2007 17:46:55 +0200 From: Ingo Molnar To: Jeremy Fitzhardinge Cc: Andi Kleen , Andrew Morton , Linus Torvalds , lkml Subject: Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries Message-ID: <20070404154655.GA31804@elte.hu> References: <20070402055652.610711908@goop.org> <20070402055704.278590661@goop.org> <200704020812.18320.ak@suse.de> <46136F25.7030907@goop.org> <20070404095745.GA16726@elte.hu> <4613C7AB.5020509@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4613C7AB.5020509@goop.org> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Jeremy Fitzhardinge wrote: > 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. sure. i simply took the middle numbers. But there's definitely a 'few percents' trend in the numbers. > > 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. if only it were not such an ugly piece of code? ;) Ingo