linux-kernel - Re: [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events

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Message-ID: <4F14FDE8.6000805@gmail.com>
Date:	Mon, 16 Jan 2012 21:49:44 -0700
From:	David Ahern <dsahern@...il.com>
To:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
CC:	Avi Kivity <avi@...hat.com>, Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [RFC][PATCH] KVM: perf: a smart tool to analyse kvm events

On 01/16/2012 07:41 PM, Xiao Guangrong wrote:
>> Have you thought about dumping a time history -- something similar to
>> what perf-script can do with dumping events but adding in kvm-specific
>> analysis like what you are doing in these examples?
>>
> 
> 
> I will look into it and put it to my todo list if it is possible.
> Thanks, David!
> 

I've played around with ways to do it as time (and motivation) allowed.
Attached is one example using perf with the trace-cmd plugin plus a
patch on perf-script to dump time between events:

perf record -e kvm:* -fo /tmp/perf.data -p 2540 -- sleep 1
perf script -i /tmp/perf.data

The output of perf-script is in the attached file. The 5th column is the
dt between successive events which is mainly a convenience.

A perf-kvm-events type command would allow more customization in the
output -- like correlating specific events and computing total time
between exit and entry accounting for HLT reasons -- as well as various
statistical dumps (average, stddev, max/min, histograms).

David

View attachment "kvm-trace-example.txt" of type "text/plain" (2525 bytes)