Re: Wiki docs on counting and tracing KVM perf events

[Jes Sorensen <Jes.Sorensen@redhat.com>]

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