[Darshan-users] Issues with Fio benchmark tool being profiled with Darshan

Snyder, Shane ssnyder at mcs.anl.gov
Wed Jul 15 13:35:27 CDT 2020

Hi Neeraj,

It looks like FIO might be using the 'openat()' call to open the files it is doing I/O to, which we only recently added support for. Assuming you aren't already, would it be possible for you to try the master branch of Darshan to see whether you can generate accurate profiles using that?

From: Darshan-users <darshan-users-bounces at lists.mcs.anl.gov> on behalf of Neeraj Rajesh <nrajesh at hawk.iit.edu>
Sent: Tuesday, July 14, 2020 3:15 PM
To: darshan-users at lists.mcs.anl.gov <darshan-users at lists.mcs.anl.gov>
Subject: [Darshan-users] Issues with Fio benchmark tool being profiled with Darshan


I am trying to profile an Fio command, where I do roughly a gigabyte of reads or writes or mixed at a fixed block size.
fio --filename=./test --size=1024MB --direct=1 --rw=randrw --bs=4k --ioengine=sync --iodepth=256 --numjobs=1 --name=test-job --minimal --stats=0
I have tested it with the following 'ioengines':
- sync
- psync
- posixaio
- pvsync

I do get a darshan file, but all of the POSIX counters are 0, except for POSIX_F_META_TIME, POSIX_STATS, POSIX_FILE_ALIGNMENT and POSIX_MMAPS. I have ensured the operation is not simultaneously doing both POSIX and STDIO.

As per my configuration it should not be getting 0s especially for the counters POSIX_SIZE_WRITE_1K_10K, POSIX_WRITES, POSIX_READS, POSIX_BYTES_WRITTEN, POSIX_BYTES_READ etc.

Kindly advise what to do next.

Thank you for your time, Stay safe
Yours Sincerely
Neeraj Rajesh
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