From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2992866AbXDDLr4 (ORCPT ); Wed, 4 Apr 2007 07:47:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S2992876AbXDDLr4 (ORCPT ); Wed, 4 Apr 2007 07:47:56 -0400 Received: from ns.suse.de ([195.135.220.2]:43940 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2992866AbXDDLrz (ORCPT ); Wed, 4 Apr 2007 07:47:55 -0400 From: Andi Kleen Organization: SUSE Linux Products GmbH, Nuernberg, GF: Markus Rex, HRB 16746 (AG Nuernberg) To: Jeremy Fitzhardinge Subject: Re: [patch 04/17] Add pagetable accessors to pack and unpack pagetable entries Date: Wed, 4 Apr 2007 13:47:42 +0200 User-Agent: KMail/1.9.6 Cc: Andrew Morton , virtualization@lists.osdl.org, lkml , Ingo Molnar References: <20070402055652.610711908@goop.org> <200704020812.18320.ak@suse.de> <46136F25.7030907@goop.org> In-Reply-To: <46136F25.7030907@goop.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200704041347.42822.ak@suse.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 04 April 2007 11:25:57 Jeremy Fitzhardinge wrote: > Andi Kleen wrote: > > What do the benchmarks say with CONFIG_PARAVIRT on native hardware > > compared to !CONFIG_PARAVIRT. e.g. does lmbench suffer? > > Barely. There's a slight hit for not using patching, and patching is > almost identical to native performance. The most noticeable difference > is in the null syscall microbenchmark, but once you get to complex > things the difference is in the noise. Why is there a difference for null syscall? I had assumed we patched all the fast path cases relevant there. Do you have an idea where it comes from? -Andi