fio version change gives different throughput results

[Thomas Weber <thomas.weber@xxxxxxxxxx>]

Hi all,

I noticed a change in the reported throughput when switching from fio version 3.17 to 3.36.

I narrowed it down to fio-3.26 which seem to introduce the throughput change. 

The exemplary fio workload attached gives me different results since then.

Was that change intended?

Thanks Thomas

fio-3.25:
Run status group 0 (all jobs):
   READ: bw=3658MiB/s (3835MB/s), 3658MiB/s-3658MiB/s (3835MB/s-3835MB/s), io=429GiB (460GB), run=120001-120001msec
  WRITE: bw=2438MiB/s (2557MB/s), 2438MiB/s-2438MiB/s (2557MB/s-2557MB/s), io=286GiB (307GB), run=120001-120001msec

fio-3.26:
Run status group 0 (all jobs):
   READ: bw=474MiB/s (497MB/s), 474MiB/s-474MiB/s (497MB/s-497MB/s), io=55.5GiB (59.6GB), run=120001-120001msec
  WRITE: bw=317MiB/s (332MB/s), 317MiB/s-317MiB/s (332MB/s-332MB/s), io=37.1GiB (39.9GB), run=120001-120001msec


FIO_FREEPARM1=description=na FIO_FREEPARM2=description=na FIO_FREEPARM3=description=na FIO_FREEPARM4=runtime=120 FIO_FREEPARM5=time_based FIO_TARGETSPEC=directory=./fsstress_data FIO_NUMJOB=1 FIO_BS=64k FIO_SIZE=1g FIO_DIRECT=0 FIO_IOENGINE=sync FIO_IODEPTH=1 fio ./fs-stress2.fiojob --output-format=normal,terse --terse-version=3 --warnings-fatal --eta=never

fs-stress2.fiojob file:
[global]
ioengine=${FIO_IOENGINE}
iodepth=${FIO_IODEPTH}
size=${FIO_SIZE}
direct=${FIO_DIRECT}
numjobs=${FIO_NUMJOB}
${FIO_TARGETSPEC}

# free parameters that can be overwritten including the var= specifier
${FIO_FREEPARM1}
${FIO_FREEPARM2}
${FIO_FREEPARM3}
${FIO_FREEPARM4}
${FIO_FREEPARM5}

# environment setup
norandommap
allrandrepeat=1
startdelay=50ms-2s
ramp_time=5s

[smallstuff-seq-slow]
rw=rw
nrfiles=1000
openfiles=25
filesize=1k-1m
bssplit=4k/20:128k/80
rwmixread=60