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Date: Mon, 30 Jun 2014 21:00:15 -0600
From: Jens Axboe <axboe@kernel.dk>
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Subject: Re: [PATCH] Log offsets of I/O operations
References: <87pphr7g5d.fsf@gmail.com> <53B1DBB8.4080901@kernel.dk> <87d2dqcak6.fsf@gmail.com> <53B1E257.5070405@kernel.dk>
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To: Abutalib Aghayev <agayev@gmail.com>
Cc: fio@vger.kernel.org
List-ID: <fio@vger.kernel.org>

On 2014-06-30 16:19, Jens Axboe wrote:
> On 2014-06-30 16:09, Abutalib Aghayev wrote:
>>
>> On Mon, Jun 30 2014 at 17:50 PM, Jens Axboe <axboe@kernel.dk> wrote:
>>> On 2014-06-29 11:43, Abutalib Aghayev wrote:
>>>>
>>>> This is a quick and dirty patch to log offsets of I/O operations as
>>>> well.  It is useful if you would like to make offset vs latency plot
>>>> for
>>>> random I/O, which may not be interesting to many people, so feel
>>>> free to
>>>> ignore it.
>>>
>>> I can definitely see this being useful. But adding 8 bytes to every log
>>> entry complicates things, as fio is already memory intensive there when
>>> logging longer runs.
>>>
>>> I'd suggest having two logging types:
>>>
>>> struct io_sample {
>>>             uint64_t time;
>>>             uint64_t val;
>>>             uint32_t ddir;
>>>             uint32_t bs;
>>>             uint64_t offset;
>>
>> I assume you didn't mean offset being here as well.
>
> Ah no, of course not.
>
>>> struct io_sample_offset {
>>>             struct io_sample s;
>>>             uint64_t offset;
>>> };
>>>
>>> and using the right type for what you are logging. This means you'd need
>>> an option to switch on the offset logging, and that you'd need to store
>>> this in the iolog struct (whether to log offset or not) and use the
>>> appropriate size for allocating and extending the log entries when
>>> needed.
>>>
>>> Make sense?
>>
>> Yes, let me rework the patch.
>
> Thanks! Note that you also need to handle the client/server part.
> Half-assed attempt attached, not tested at all. Still needs the client
> part update.

I finished off the client bit and committed it, it was just a few lines 
of change and it was done. Also added documentation, etc. So current 
-git should be complete.

-- 
Jens Axboe