# mount | grep /mnt/ext4
/dev/sdc1 on /mnt/ext4 type ext4 (rw,noatime,nodiratime,discard,data=writeback,barrier=0
# fio --filename=/mnt/ext4/test --direct=1 --rw=randrw --bs=16k --size=50G --numjobs=16 --runtime=120 --group_reporting --name=test --rwmixread=90 --thread --ioengin =psync
test: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=psync, iodepth=1
...
test: (g=0): rw=randrw, bs=16K-16K/16K-16K, ioengine=psync, iodepth=1
fio 1.58
Starting 16 threads
Jobs: 16 (f=16): [mmmmmmmmmmmmmmmm] [100.0% done] [184.6M/22396K /s] [11.6K/1367  iops] [eta 00m:00s]
test: (groupid=0, jobs=16): err= 0: pid=3729
  read : io=21747MB, bw=185572KB/s, iops=11598 , runt=120002msec
    clat (usec): min=52 , max=155186 , avg=1366.02, stdev=1030.61
     lat (usec): min=52 , max=155186 , avg=1366.16, stdev=1030.61
    bw (KB/s) : min= 8160, max=13184, per=6.26%, avg=11609.18, stdev=427.55
  write: io=2413.7MB, bw=20596KB/s, iops=1287 , runt=120002msec
    clat (usec): min=44 , max=123228 , avg=101.58, stdev=597.38
     lat (usec): min=44 , max=123228 , avg=101.73, stdev=597.38
    bw (KB/s) : min=  528, max= 2043, per=6.26%, avg=1288.69, stdev=206.71
  cpu          : usr=4.71%, sys=19.46%, ctx=27661405, majf=0, minf=7928
  IO depths    : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued r/w/d: total=1391810/154470/0, short=0/0/0
     lat (usec): 50=0.01%, 100=8.35%, 250=1.60%, 500=0.10%, 750=0.07%
     lat (usec): 1000=4.46%
     lat (msec): 2=81.23%, 4=0.60%, 10=3.56%, 20=0.01%, 50=0.01%
     lat (msec): 100=0.01%, 250=0.01%

Run status group 0 (all jobs):
   READ: io=21747MB, aggrb=185571KB/s, minb=190025KB/s, maxb=190025KB/s, mint=120002msec, maxt=120002msec
  WRITE: io=2413.7MB, aggrb=20595KB/s, minb=21089KB/s, maxb=21089KB/s, mint=120002msec, maxt=120002msec

Disk stats (read/write):
  sdc: ios=1391501/154483, merge=0/23, ticks=1870560/11224, in_queue=1880960, util=99.97%