From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752237AbXDDQKf (ORCPT ); Wed, 4 Apr 2007 12:10:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753119AbXDDQKf (ORCPT ); Wed, 4 Apr 2007 12:10:35 -0400 Received: from gw.goop.org ([64.81.55.164]:39743 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752395AbXDDQKe (ORCPT ); Wed, 4 Apr 2007 12:10:34 -0400 Message-ID: <4613CDE8.2000806@goop.org> Date: Wed, 04 Apr 2007 09:10:16 -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> <4613C7AB.5020509@goop.org> <20070404154655.GA31804@elte.hu> In-Reply-To: <20070404154655.GA31804@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: > sure. i simply took the middle numbers. But there's definitely a 'few > percents' trend in the numbers. > Yep. I guess the thing that coloured my summary is that I found overhead of unpatched paravirt_ops calls surprisingly small. I was really expecting more like ~10% hit, but only null syscall approached that. >>> 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? ;) > Sigh, yes. I've cleaned it up a bit since the last post, and commented it, but I couldn't do much with its essential ugliness. But I guess it just got promoted from "ugly" to "ugly but necessary". J