Thanks for your response and also your consideration.
Good Luck
On Fri, Apr 24, 2015 at 1:16 PM, Jens Axboe <axboe@xxxxxxxxx> wrote:
> On 04/24/2015 11:10 AM, Mansour Shafaei Moghaddam wrote:
>>
>> But I still think that the time is not relative to anything except the
>> beginning of the job i.e., 0:00:00. I again tried running the
>> following trace:
>>
>> io version 2 iolog
>> /dev/sde add
>> /dev/sde open
>> /dev/sde read 1499999997952 16384
>> /dev/sde read 4499992682496 16384
>> /dev/sde read 4499992682496 16384
>> /dev/sde wait 3000 16384
>> /dev/sde read 4499992682496 16384
>> /dev/sde read 4499992682496 16384
>> /dev/sde read 4499992682496 16384
>> /dev/sde wait 5000 16384
>> /dev/sde read 1499999997952 16384
>> /dev/sde read 4499993485312 16384
>> /dev/sde read 4499993485312 16384
>> /dev/sde read 4499993485312 16384
>> /dev/sde read 4499993485312 16384
>> /dev/sde read 4499993485312 16384
>> /dev/sde close
>>
>> with the job file shown below:
>>
>>
>> [global]
>> log_offset=1
>> direct=1
>> ioengine=sync
>> [read-phase]
>> write_lat_log=test
>> read_iolog=testtrace
>>
>> Here is what I see in the clat file:
>>
>>
>> 22, 22165, 0, 16384, 1499999997952
>> 48, 25752, 0, 16384, 4499992682496
>> 58, 10044, 0, 16384, 4499992682496
>> 2907, 8123, 0, 16384, 4499992682496
>> 2917, 10077, 0, 16384, 4499992682496
>> 2927, 10002, 0, 16384, 4499992682496
>> 4918, 18610, 0, 16384, 1499999997952
>> 4942, 24021, 0, 16384, 4499993485312
>> 4952, 10018, 0, 16384, 4499993485312
>> 4962, 10017, 0, 16384, 4499993485312
>> 4972, 10030, 0, 16384, 4499993485312
>> 4982, 10029, 0, 16384, 4499993485312
>>
>> As you can see submission times are like
>> (22,....,2907,.....,4918,...). So the given value as offset is being
>> interpreted as absolute delay. In other words it is the time stamp for
>> the IO right after that. If it is less than the current time of the
>> job it will be ignored. Otherwise, it will be applied.
>
>
> Yeah, I was too quick, looking at the code, on reading the log, we store
> offset in delay directly:
>
> if (rw == DDIR_WAIT) {
> ipo->delay = offset;
> } else {
>
> and on retrieval, we factor in the 'td' time offset as an absolute delay.
>
> --
> Jens Axboe
>
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