From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jes Sorensen Subject: Re: Wiki docs on counting and tracing KVM perf events Date: Thu, 20 May 2010 10:24:49 +0200 Message-ID: <4BF4F1D1.6030203@redhat.com> References: <4BEC1345.7040408@redhat.com> <4BF4EF97.5060705@redhat.com> <4BF4F07F.4020007@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Stefan Hajnoczi , kvm To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:21064 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753803Ab0ETIYz (ORCPT ); Thu, 20 May 2010 04:24:55 -0400 In-Reply-To: <4BF4F07F.4020007@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 05/20/10 10:19, Avi Kivity wrote: > On 05/20/2010 11:15 AM, Jes Sorensen wrote: >>> Two things are missing to make this really useful: >>> >>> - a continuously updating difference mode like kvm_stat >>> - subevents; for example kvm:kvm_exit is an aggregate of all exit types >>> that can be split using filters to show individual exit reason >>> statistics >>> >> Third missing item, which I find really useful: >> - run once spit out raw counters >> >> For some operations, like file system benchmarking, it is useful to >> sample the counters before and after and then divide the raw number of >> events by the number of IOPS performed by the benchmark. If perf spits >> out events/sec it's kinda hard to get this. >> > > That's 'perf stat -a sleep 2' sleep 2 doesn't really cut it, I guess you could do it with perf stat -a sleep 0.1 but to be honest, that is pretty ugly. Something like this would be a lot nicer: perf stat -a -raw Jes