Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754859AbZFEObv (ORCPT ); Fri, 5 Jun 2009 10:31:51 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752172AbZFEObo (ORCPT ); Fri, 5 Jun 2009 10:31:44 -0400 Received: from ozlabs.org ([203.10.76.45]:55258 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751736AbZFEObn (ORCPT ); Fri, 5 Jun 2009 10:31:43 -0400 From: Rusty Russell To: Gerd Hoffmann Subject: Re: [benchmark] 1% performance overhead of paravirt_ops on native kernels Date: Sat, 6 Jun 2009 00:01:36 +0930 User-Agent: KMail/1.11.2 (Linux/2.6.28-11-generic; KDE/4.2.2; i686; ; ) Cc: Dave McCracken , Linus Torvalds , Ingo Molnar , Nick Piggin , Jeremy Fitzhardinge , "H. Peter Anvin" , Thomas Gleixner , Linux Kernel Mailing List , Andrew Morton , Peter Zijlstra , Avi Kivity , Arjan van de Ven References: <4A0B62F7.5030802@goop.org> <200906041652.55298.dcm@mccr.org> <4A28C9CD.2010208@redhat.com> In-Reply-To: <4A28C9CD.2010208@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200906060001.38069.rusty@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1322 Lines: 29 On Fri, 5 Jun 2009 05:01:25 pm Gerd Hoffmann wrote: > Hi, > > > I think you're missing the point of Rusty's benchmark. I see his > > exercise as "compare a kernel configured as a distro would vs a > > custom-built kernel configured for the exact target environment". In > > that light, questions about the CONFIG options Rusty used should be based > > on whether most distros would use them in their stock kernels as opposed > > to how necessary they are. > > Well. The test ran on a machine with so much memory that you need > HIGHMEM to use it all. I think it also was SMP. So a custom kernel for > *that* machine would certainly include SMP and HIGHMEM ... I have a UP machine with 512M of RAM, but I wasn't going to take it out just to prove the point. Hence I used my test machine with mem=880 maxcpus=1 to simulate it, but that's a distraction here. > While it might be > interesting by itself to see what the overhead of these config options > is, it is IMHO quite pointless *in the context of this discussion*. No, you completely missed the point. Rusty. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/