Re: problem with fio --client and latency logs

[Jens Axboe <axboe@kernel.dk>]

On 05/27/2016 08:43 AM, Jens Axboe wrote:
> On 05/26/2016 01:11 PM, Ben England wrote:
>> recently I noticed a problem in master branch when fio --client is
>> used.  latency logs generated with it have large numbers of "0, 0, 0,
>> 0" records at the end of the file.  I have a simple reproducer fio
>> jobfile:
>>
>> --------- reproducer.fiojob ----
>> [global]
>> numjobs=1
>> directory=/var/tmp
>>
>> [shared-files]
>> rw=randread
>> write_lat_log=1thr
>> ioengine=sync
>> bs=4k      # I/O size
>> filesize=1g  # file size
>> runtime=20
>> -------------
>>
>> If you run this job file like this:
>>
>> # fio --server --daemonize=/var/run/fiosvr.pid
>> # fio --client=localhost reproducer.fiojob
>>
>> You get the latency log 1thr_clat.1.log with the 0 records at the
>> end.  If you run the same job file with:
>>
>> # fio reproducer.fiojob
>>
>> You don't get the 0 records.  This explains why Ceph CBT does not have
>> the problem, for example.
>>
>> I bisected fio history using git until I found the first commit that
>> failed:
>>
>> -------
>> commit 0cba0f919ee6af7dd65df436884336cff9c903f9
>> Author: Jens Axboe <axboe@fb.com>
>> Date:   Thu Dec 17 14:54:15 2015 -0700
>>
>>      client/server: transparent handling of storing compressed logs
>>
>>      Signed-off-by: Jens Axboe <axboe@fb.com>
>> ------
>>
>> I could use some help figuring out what went wrong at this point, the
>> diffs were complicated but it seemed possible that this commit was
>> related to my problem.
>
> I have a good idea what this might be, I'll take a look at it.

http://git.kernel.dk/cgit/fio/commit/?id=e35fb4c43ecc5b9d35cb5d980e811d3408fc5a4e

This should fix it, can you try with current -git?

-- 
Jens Axboe