Re: [PATCH] add PLE stats to kvmstat

[Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>]

On 07/08/2012 05:50 PM, Avi Kivity wrote:
> On 07/06/2012 09:12 PM, Andrew Theurer wrote:
>> On Sat, 2012-07-07 at 01:40 +0800, Xiao Guangrong wrote:
>>> On 07/06/2012 09:22 PM, Andrew Theurer wrote:
>>>> On Fri, 2012-07-06 at 15:42 +0800, Xiao Guangrong wrote:
>>>>> On 07/06/2012 05:50 AM, Andrew Theurer wrote:
>>>>>> I, and I expect others, have a keen interest in knowing how often we
>>>>>> exit for PLE, and also how often that includes a yielding to another
>>>>>> vcpu.  The following adds two more counters to kvmstat to track the
>>>>>> exits and the vcpu yields.  This in no way changes PLE behavior, just
>>>>>> helps us track what's going on.
>>>>>>
>>>>>
>>>>> Tracepoint is a better choice than the counters you used. :)
>>>>
>>>> Xiao, is kvmstat considered to be deprecated?  Or are debug stats like
>>>> this just generally favored to be processed via something like perf
>>>> instead of debugfs?
>>>
>>> Andrew, please refer to Documentation/feature-removal-schedule.txt,
>>> it says:
>>>
>>> What:   KVM debugfs statistics
>>> When:   2013
>>> Why:    KVM tracepoints provide mostly equivalent information in a much more
>>>         flexible fashion.
>>>
>>> You can use tracepoints instead of your debugfs-counters in this patch.
>>
>> Great, thanks.  I will work on a tracepoint based approach.
>>>
>>>>  Should we be removing kvmstat?
>>>>
>>>
>>> Some months ago, i implemented 'perf kvm-events' which can analyse kvm
>>> events more smartly, the patchset can be found at:
>>> 	https://lkml.org/lkml/2012/3/6/86
>>
>> I will take a look.
>>>
>>> Avi said it may instead of kvmstat, but i am too busy to update this
>>> patchset. :)
>>>
> 
> Note, kvm_stat is able to use both the old debugfs based statistics and
> the tracepoint based events.  The latter requires root privileges.
> 

Yes, but you are going to remove KVM debugfs statistics, will you
plan to remove kvm_stat after debugfs based statistics removed and
kvm-events merged?

> (bonus: pressing 'x' expands the kvm_exit statistic to include
> information about the various hardware exit reasons).

Yes, i noticed that, good feature, thank you, Avi!