[Gluster-users] What's the impact of enabling the profiler?

Pranith Kumar Karampuri pkarampu at redhat.com
Tue Jul 22 06:30:39 UTC 2014

On 07/22/2014 11:56 AM, Joe Julian wrote:
> On 07/21/2014 11:20 PM, Pranith Kumar Karampuri wrote:
>> On 07/22/2014 11:39 AM, Joe Julian wrote:
>>> On 07/17/2014 07:30 PM, Pranith Kumar Karampuri wrote:
>>>> On 07/18/2014 03:05 AM, Joe Julian wrote:
>>>>> What impact, if any, does starting profiling (gluster volume 
>>>>> profile $vol start) have on performance?
>>>> Joe,
>>>>     According to the code the only extra things it does is calling 
>>>> gettimeofday() call at the beginning and end of the FOP to 
>>>> calculate latency, increment some variables. So I guess not much?
>>> So far so good. Is the only way to clear the stats to restart the 
>>> brick?
>> I think when the feature is initially proposed we wanted two things
>> 1) cumulative stats
>> 2) Interval stats
>> Interval stats get cleared whenever 'gluster volume profile <volname> 
>> info' is executed (Although it starts counting the next set of fops 
>> that happen after this command execution). But there is no way to 
>> clear the cumulative stats. It would be nice if you could give some 
>> feedback about what you liked/what you think should change to make 
>> better use of it. So I am guessing there wasn't big performance hit?
>> Pranith
> No noticeable performance hit, no.
> I'm writing a whitepaper for the best practices for OpenStack on 
> GlusterFS so I needed some idea how qemu actually uses the filesystem. 
> What the operations are so I can look at not only the best ways to 
> tune for that use, but how to build the systems around that.
> At this point, I'm just collecting data. TBH, I hadn't noticed the 
> interval data. That should be perfect for this. I'll poll it in XML 
> and run the numbers in a few days.
      Do let us know your feedback. It needs some real-world usage 
suggestions from users like you :-).


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