From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933603Ab0CLRS3 (ORCPT ); Fri, 12 Mar 2010 12:18:29 -0500 Received: from lider.pardus.org.tr ([193.140.100.216]:51294 "EHLO lider.pardus.org.tr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933518Ab0CLRSX (ORCPT ); Fri, 12 Mar 2010 12:18:23 -0500 Message-ID: <4B9A775D.5070303@pardus.org.tr> Date: Fri, 12 Mar 2010 19:18:21 +0200 From: =?UTF-8?B?T3phbiDDh2HEn2xheWFu?= User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: "linux-kernel@vger.kernel.org" , Avi Kivity Subject: Re: Poor KVM guest performance on an HP rack server References: <4B243B2B.806@pardus.org.tr> <4B24856A.4020507@goop.org> <4B24BE17.805@pardus.org.tr> <4B2532A0.2070001@goop.org> In-Reply-To: <4B2532A0.2070001@goop.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge wrote: > On 12/13/09 02:12, Ozan Çağlayan wrote: >> Hmm, that's because we're using/developing a Linux distribution which >> doesn't have 64-bit support yet. But since the guest will be a >> compile-farm for our needs, it's worth trying to run an 64-bit distro on >> the host to see the difference, thanks for the tip but how much should >> this affect the performance? > > 32-bit PAE is marginal above 4G of memory and the limit is at about 8G. > Above that, so much lowmem (<~1GB) is occupied by page and other kernel > structures that there's barely any memory to do any real work. If this > is what's happening, you'd expect to see poor host performance, and slow > guest performance would be secondary to that. Updates on the issue after 3 months: ------------------------------------ The host is now running an x86_64 2.6.32.9 kernel with kvm-2.6.32.7 built as an external module. The guest is 32-bit 2.6.32.9. I've booted the guest with -smp 4 -m 4096 and I'm seeing the same slowness that I've mentioned in this thread during CUPS configuration. I'll try to send kvm_stat output in this week and try the same configure on another guest OS to see if it differs or not. I'm also thinking to build an optimized 2.6.33 for that rack server to see if things get better or not. Thanks, Ozan Caglayan