Re: Increasing FIO performance

Lombardi, Johann

Hi Eeheet,


You can use the fio DAOS engine (


If you want to stick to dfuse, then I would advise to use the posixaio engine instead of pvsync. pvsync is synchronous/blocking and won’t be able to submit more than one I/O at a time (in the “IO depths” section of your fio output, you have “1 = 100%”). Please also note that the FUSE kernel module takes a per-file mutex on every write (and not on read), so all writes to a file are effectively serialized. I haven’t checked whether this has been improved with recent Linux kernels though.





From: <> on behalf of "Hayer, Eeheet" <eeheet.hayer@...>
Reply-To: "" <>
Date: Tuesday 27 July 2021 at 17:57
To: "" <>
Subject: [daos] Increasing FIO performance




I’m an intern on the HPC team, and I’m trying to increase the performance of FIO on my server (wolf-169), admin/client (wolf-57). I attached a screencap of what I’m currently getting and am told I should be getting much higher numbers.


My server has 2 SSDs, and some non-optane pmem.


The command I’m running:

$ /usr/bin/fio --name=random-write --ioengine=pvsync --rw=randwrite --bs=4k --size=128M --nrfiles=4 --directory=/tmp/daos_test1 --numjobs=8 --iodepth=16 --runtime=60 --time_based --direct=1 --buffered=0 --randrepeat=0 --norandommap --refill_buffers





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