Re: bug in logging code?

[Jens Axboe <axboe@kernel.dk>]

On 04/02/2014 11:53 AM, Mark Nelson wrote:
> On 04/02/2014 12:38 PM, Jens Axboe wrote:
>> On 04/02/2014 09:23 AM, Mark Nelson wrote:
>>> I've been playing around with usng the various write_*_log options in
>>> fio to record run statistics.  What I'm finding is that some of the logs
>>> have malformed lines in them.  The following snippet is from the bw log:
>>>
>>> 811820, 12263, 0, 4194304
>>> 812619, 35929, 0, 4194304
>>> 818437, 8448, 0, 419430, 4194304
>>> 1256299, 160627, 0, 4194304
>>> 1256831, 154274, 0, 4194304
>>>
>>> Notice that the malformed line appears to be a partial write that gets
>>> truncated.  The fio command being used to run the tests is
>>> autogenerated, so job files aren't used.  here's the one that created
>>> the above log snippet:
>>>
>>> /home/nhm/bin/fio
>>> --rw=read
>>> --ioengine=libaio
>>> --runtime=7200
>>> --ramp_time=0
>>> --numjobs=1
>>> --direct=1
>>> --bs=4194304B
>>> --iodepth=16
>>> --size=9216M
>>> --write_iops_log=/tmp/cbt/ceph/kvmrbdfio/osd_ra-00004096/client_ra-00000128/op_size-04194304/concurrent_procs-008/iodepth-016/read/output
>>>
>>>
>>>
>>> --write_bw_log=/tmp/cbt/ceph/kvmrbdfio/osd_ra-00004096/client_ra-00000128/op_size-04194304/concurrent_procs-008/iodepth-016/read/output
>>>
>>>
>>>
>>> --write_lat_log=/tmp/cbt/ceph/kvmrbdfio/osd_ra-00004096/client_ra-00000128/op_size-04194304/concurrent_procs-008/iodepth-016/read/output
>>>
>>>
>>>
>>> --time_based
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-0
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-1
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-2
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-3
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-4
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-5
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-6
>>> --name=/srv/rbdfio-`hostname -s`-0/cbt-kvmrbdfio-7
>>>
>>> The --numjobs=1 line should be removed, but I believe it gets overridden
>>> anyway with multiple name parameters.  I wonder if having multiple name
>>> parameters (ie multiple fio processes) is causing those processes to all
>>> try to write to the same log files, potentially at the same time?  Any
>>> thoughts would be much appreicated!
>>
>> What version of fio are you running?
>>
>
> f42557f (ie master from yesterday) with a slightly different fix for the
> basename issues that just got resolved.
>
> I can verify now that running fio with a single --name flag appears to
> generate logs without malformated lines.

OK, I'll take a look, We should already be serializing the writing to 
the same log files, but your example definitely looks like we are not.

BTW, the numjobs option applies to each --name section. Just to clear 
that up from your original email. So you really get numjobs * 
name_sections running.

-- 
Jens Axboe