Fixed rate submission failed with offload mode and io_uring as ioengine.

[axboe]

From REPORTING-BUGS:

Reporting a bug

If you notice anything that seems like a fio bug, please do send email to the list (fio@vger.kernel.org, see README) about it. If you are not running the newest release of fio, upgrading first is recommended.

When reporting a bug, you'll need to include:

1) A description of what you think the bug is 2) Environment (Linux distro version, kernel version). This is mostly needed if it's a build bug. 3) The output from fio --version. 4) How to reproduce. Please include a full list of the parameters passed to fio and the job file used (if any).

A bug report can't have too much information. Any time information that is left out and has to be asked for will add to the turn-around time of getting to the bottom of the issue, and an eventual fix.

[taoluo]

A description of what you think the bug is fixed rate submission job fails with offload mode and io_uring as ioengine.

Environment (Linux distro version, kernel version). This is mostly needed if it's a build bug. Linux mars 5.3.0-23-generic #25-Ubuntu SMP Tue Nov 12 09:22:33 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

The output from fio --version. fio-3.16-49-gcc16

How to reproduce. Please include a full list of the parameters run fio with following job file "fixed_rate_submission":

[poisson-rate-submit]
size=128m
rw=randread
ioengine=io_uring
iodepth=32
direct=1

# by setting the submit mode to offload, we can guarantee a fixed rate of
# submission regardless of what the device completion rate is.
io_submit_mode=offload
rate_iops=500

# Real world random request flow follows Poisson process. To give better
# insight on latency distribution, we simulate request flow under Poisson
# process.
rate_process=poisson
percentile_list=50:99:99.9

passed to fio and the job file used (if any). fio fixed_rate_submission.fio

[taoluo]

The output shows

Starting 1 process
fio: pid=11807, got signal=11

So, I guess there is segmentation fault.

[axboe]

Thanks for the detailed info, I'll take a look.

[sitsofe]

(Pinging @axboe on this one)