From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Performace data when running Windows VMs Date: Wed, 26 Aug 2009 19:26:45 +0300 Message-ID: <4A956245.90102@redhat.com> References: <1251298670.9683.65.camel@twinturbo.austin.ibm.com> <4A95586D.5010403@redhat.com> <1251303297.9683.82.camel@twinturbo.austin.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Yan Vugenfirer To: habanero@linux.vnet.ibm.com Return-path: Received: from mx1.redhat.com ([209.132.183.28]:10398 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750935AbZHZQ04 (ORCPT ); Wed, 26 Aug 2009 12:26:56 -0400 In-Reply-To: <1251303297.9683.82.camel@twinturbo.austin.ibm.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/26/2009 07:14 PM, Andrew Theurer wrote: > On Wed, 2009-08-26 at 18:44 +0300, Avi Kivity wrote: > >> On 08/26/2009 05:57 PM, Andrew Theurer wrote: >> >>> I recently gathered some performance data when running Windows Server >>> 2008 VMs, and I wanted to share it here. There are 12 Windows >>> Server2008 64-bit VMs (1 vcpu, 2 GB) running which handle the concurrent >>> execution of 6 J2EE type benchmarks. Each benchmark needs a App VM and >>> a Database VM. The benchmark clients inject a fixed rate of requests >>> which yields X% CPU utilization on the host. A different hypervisor was >>> compared; KVM used about 60% more CPU cycles to complete the same amount >>> of work. Both had their hypervisor specific paravirt IO drivers in the >>> VMs. >>> >>> Server is a 2 socket Core/i7, SMT off, with 72 GB memory >>> >>> >> Did you use large pages? >> > Yes. > The stats show 'largepage = 12'. Something's wrong. There's a commit (7736d680) that's supposed to fix largepage support for kvm-87, maybe it's incomplete. >>> I/O on the host was not what I would call very high: outbound network >>> averaged at 163 Mbit/s inbound was 8 Mbit/s, while disk read ops was >>> 243/sec and write ops was 561/sec >>> >>> >> What was the disk bandwidth used? Presumably, direct access to the >> volume with cache=off? >> > 2.4 MB/sec write, 0.6MB/sec read, cache=none > The VMs' boot disks are IDE, but apps use their second disk which is > virtio. > Chickenfeed. Do the network stats include interguest traffic? I presume *all* of the traffic was interguest. >> linux-aio should help reduce cpu usage. >> > I assume this is in a newer version of Qemu? > No, posted and awaiting merge. >> Could it be that Windows uses the debug registers? Maybe we're >> incorrectly deciding to switch them. >> > I was wondering about that. I was thinking of just backing out the > support for debugregs and see what happens. > > Did the up/down_read seem kind of high? Are we doing a lock of locking? > It is. We do. Marcelo made some threats to remove this lock. -- error compiling committee.c: too many arguments to function