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 10:44:28 -0400 Message-ID: <521CBB4C.4080004@gameservers.com> References: <521BA934.3050507@gameservers.com> <521C52A8.40801@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Paolo Bonzini Return-path: Received: from mail.choopa.net ([216.155.136.52]:36376 "EHLO mail.choopa.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752881Ab3H0Oo3 (ORCPT ); Tue, 27 Aug 2013 10:44:29 -0400 In-Reply-To: <521C52A8.40801@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 8/27/2013 3:18 AM, Paolo Bonzini wrote: > Il 26/08/2013 21:15, Brian Rak ha scritto: >> Samples: 62M of event 'cycles', Event count (approx.): 642019289177 >> 64.69% [kernel] [k] _raw_spin_lock >> 2.59% qemu-system-x86_64 [.] 0x00000000001e688d >> 1.90% [kernel] [k] native_write_msr_safe >> 0.84% [kvm] [k] vcpu_enter_guest >> 0.80% [kernel] [k] __schedule >> 0.77% [kvm_intel] [k] vmx_vcpu_run >> 0.68% [kernel] [k] effective_load >> 0.65% [kernel] [k] update_cfs_shares >> 0.62% [kernel] [k] _raw_spin_lock_irq >> 0.61% [kernel] [k] native_read_msr_safe >> 0.56% [kernel] [k] enqueue_entity > Can you capture the call graphs, too (perf record -g)? Sure. I'm not entire certain how to use perf effectively. I've used `perf record`, then manually expanded the call stacks in `perf report`. If this isn't what you wanted, please let me know. https://gist.github.com/devicenull/7961f23e6756b647a86a/raw/a04718db2c26b31e50fb7f521d47d911610383d8/gistfile1.txt >> 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 (b) service NMIs. In fact, every NMI is reading the > timer too and causing an exit to QEMU. > > So it is also possible that you have to debug this inside the guest, to > see if these exits are expected or not. Do you have any suggestions for how I would do this? Given that the guest is Windows, I'm not certain how I could even begin to debug this. Also, for that patch set I found, do I also need a patch for qemu to actually enable the new enlightenment? I haven't been able to find anything for qemu that matches that patch. I did find http://www.mail-archive.com/kvm@vger.kernel.org/msg82495.html , but that's from significantly before the patchset, so I can't tell if that's still related.