Re: [Bug report] Runtime, IOPS, bandwidth recorded incorrectly if small size with time_based

[Jens Axboe <axboe@kernel.dk>]

On 05/04/2015 04:02 PM, Jens Axboe wrote:
> On 05/04/2015 03:25 PM, Brian Fulton wrote:
>> Hi Jens,
>>
>> I've been actively looking at this bug.  It was introduced with change
>> e5437a073e658e8154b9e87bab5c7b3b06ed4255
>> (https://github.com/axboe/fio/commit/e5437a073e658e8154b9e87bab5c7b3b06ed4255).
>>
>>
>> In this change, the time granularity was changed from microseconds to
>> milliseconds.  This change assumes that all loops take at least 1ms to
>> complete.  This is not always true and tests where the loop gets
>> processed, regularly, in sub-millisecond time result in many zeroes
>> being summed which, ultimately, causes a completely inaccurate
>> runtime.
>>
>> I have a fix for this, but I want to verify that it doesn't break
>> anything as it is changing the way the runtime is being calculated.
>>
>> We are using fio version 2.2.6, though this issue should still be
>> present in the latest version (2.2.7).
>>
>>
>> Below is a patch fix based of the latest version of fio 2.2.7:
>
> Thanks, that makes more sense. Akash, can you confirm that this fixes it
> for you?

Committed:

http://git.kernel.dk/?p=fio.git;a=commit;h=95603b7470fac1917cb11bc686e60b4339f8a2fc

Brian, I changed a few things:

- DDIR_RWDIR_CNT exists for array sizing
- You need a ',' after that zero to clear the array
- Style

-- 
Jens Axboe