From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030589Ab2GLPU7 (ORCPT ); Thu, 12 Jul 2012 11:20:59 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:43571 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932558Ab2GLPU5 (ORCPT ); Thu, 12 Jul 2012 11:20:57 -0400 Message-ID: <4FFEEB55.5070009@gmail.com> Date: Thu, 12 Jul 2012 09:20:53 -0600 From: David Ahern User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:13.0) Gecko/20120614 Thunderbird/13.0.1 MIME-Version: 1.0 To: Gleb Natapov CC: Peter Zijlstra , Avi Kivity , LKML Subject: Re: perf with precise attribute kills all KVM based VMs References: <4FFAED16.7050204@redhat.com> <4FFAEF13.7010108@gmail.com> <1341845396.3462.81.camel@twins> <4FFAEFF1.9000706@redhat.com> <1341845999.3462.86.camel@twins> <4FFCBD00.1030109@gmail.com> <20120711071006.GF23898@redhat.com> <1342000187.3462.134.camel@twins> <20120711095337.GJ23898@redhat.com> <4FFE4E8D.90606@gmail.com> <20120712042923.GG7298@redhat.com> In-Reply-To: <20120712042923.GG7298@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/11/12 10:29 PM, Gleb Natapov wrote: > On Wed, Jul 11, 2012 at 10:11:57PM -0600, David Ahern wrote: >> On 7/11/12 3:53 AM, Gleb Natapov wrote: >>> On Wed, Jul 11, 2012 at 11:49:47AM +0200, Peter Zijlstra wrote: >>>> On Wed, 2012-07-11 at 10:10 +0300, Gleb Natapov wrote: >>>> >>>>> Looks like Avi is right about the overshoot. Can you test something like this? >>>>> >>>>> diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c >>>>> index 166546e..5fb371a 100644 >>>>> --- a/arch/x86/kernel/cpu/perf_event_intel.c >>>>> +++ b/arch/x86/kernel/cpu/perf_event_intel.c >>>>> @@ -1374,8 +1374,11 @@ static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr) >>>>> arr[0].msr = MSR_CORE_PERF_GLOBAL_CTRL; >>>>> arr[0].host = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_guest_mask; >>>>> arr[0].guest = x86_pmu.intel_ctrl & ~cpuc->intel_ctrl_host_mask; >>>>> + arr[1].msr = MSR_IA32_PEBS_ENABLE; >>>>> + arr[1].host = cpuc->pebs_enabled; >>>>> + arr[1].guest = 0; >>>>> + *nr = 2; >>>>> >>>>> - *nr = 1; >>>>> return arr; >>>>> } >>>> >> >> So far the 64-bit Fedora 10 VM with both a Fedora 10 stock kernel >> and a 2.6.38 kernel have not faired well - and that's the only VM I >> have tried at the moment. Using -e cycles:pp I have been able to >> lock up the VM 3 times out of 3 series of tests with perf-kvm that >> includes network traffic (e.g., netperf), disk I/O (dd based to >> create a file with dsync flag) and pure userspace cpu bound (openssl >> speed). May or may not be related. >> > OK that's may be BTSes. What about -e cycles:p? BTW are you using your > patch to set exclude_guest parameter? If not use -e cycles:Hp. I started with cycles:pp; should not really matter - they all need to work without blowing up VMs (cycles:p, cycles:pH, cycles:pG, cycles:pp, cycles:ppH, cycles:ppG). For grins I ran a quick test while reading emails this morning. This time a fedora 17 VM with 3.4.0-1.fc17.x86_64 kernel. It too locks up pretty quickly - just a couple of iterations of perf: perf kvm --guestmount=/tmp/guest-mount record -fo /tmp/perf.data -a -v -e cycles:pH -- sleep 60 Note the :pH this time. I did not have netserver installed in the VM so used a ping flood for network traffic. > >> Also, I noted that 'perf kvm --guest record -e cycles:pp' does not >> generate a whole lot of samples -- like < 100 in a 20-second sample >> -- despite the fact that the guest is rather busy. >> > Host events do not suppose to generate events while guest is running. My server has 16 cpus and the VM has only 2 vcpus; with the -a I would expect some host sampling. Note: in the above case :pp resets the exclude-host modifier set by the perf-kvm part, so hosts samples are not excluded. See parse_events_modifier(). So, is the idea of your patch to not enable the PEBS in guest mode? David