[Gluster-devel] [Gluster-users] What's the impact of enabling the profiler?
Joe Julian
joe at julianfamily.org
Tue Jul 22 06:26:23 UTC 2014
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.
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