Re: [PATCH] add PLE stats to kvmstat

[Avi Kivity <avi@redhat.com>]

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.

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

-- 
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