From mboxrd@z Thu Jan 1 00:00:00 1970 From: Brian Rak Subject: Re: Windows Server 2008R2 KVM guest performance issues Date: Tue, 27 Aug 2013 10:09:11 -0400 Message-ID: <521CB307.2000102@gameservers.com> References: <521BA934.3050507@gameservers.com> <521C52A8.40801@redhat.com> <20130827073833.GD22899@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Paolo Bonzini , kvm@vger.kernel.org To: Gleb Natapov Return-path: Received: from mail.choopa.net ([216.155.136.52]:35807 "EHLO mail.choopa.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753298Ab3H0OJM (ORCPT ); Tue, 27 Aug 2013 10:09:12 -0400 In-Reply-To: <20130827073833.GD22899@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 8/27/2013 3:38 AM, Gleb Natapov wrote: > On Tue, Aug 27, 2013 at 09:18:00AM +0200, Paolo Bonzini wrote: >>> I've captured 20,000 lines of kvm trace output. This can be found >>> https://gist.github.com/devicenull/fa8f49d4366060029ee4/raw/fb89720d34b43920be22e3e9a1d88962bf305da8/trace >> The guest is doing quite a lot of exits per second, mostly to (a) access >> the ACPI timer > I see a lot of PM timer access not ACPI timer. The solution for that is > the patchset Brian linked. > >> (b) service NMIs. In fact, every NMI is reading the >> timer too and causing an exit to QEMU. >> > Do you mean "kvm_exit: reason EXCEPTION_NMI rip 0xfffff800016dcf84 info > 0 80000307"? Those are not NMIs, single NMI will kill Windows, they are #NM > exceptions. Brian, is your workload uses floating point calculation? Yes, our workload uses floating point heavily. I'd also strongly suspect it's doing various things with timers quite frequently. (This is all third party software, so I don't have the source to examine to determine exactly what it's doing).