Hi,
I run into this problem probably because I did not understand the
command correctly.
But my test.fio configured as follow:
[global]
bs=4k
ba=512b
direct=1
number_ios=400
rw=write:2k
ioengine=sg
iodepth=2
iodepth_batch=2
write_bw_log=test
write_lat_log=test
write_iops_log=test
[/dev/sdb]
and the result looks like this:
/dev/sdb: (groupid=0, jobs=1): err= 0: pid=7783: Mon Nov 17 15:26:30 2014
write: io=1600.0KB, bw=6584.4KB/s, iops=1646, runt= 243msec
clat (usec): min=153, max=14926, avg=602.43, stdev=1165.02
lat (usec): min=153, max=14926, avg=602.91, stdev=1165.03
clat percentiles (usec):
| 1.00th=[ 163], 5.00th=[ 193], 10.00th=[ 253], 20.00th=[ 290],
| 30.00th=[ 322], 40.00th=[ 354], 50.00th=[ 394], 60.00th=[ 446],
| 70.00th=[ 482], 80.00th=[ 532], 90.00th=[ 708], 95.00th=[ 1048],
| 99.00th=[ 6624], 99.50th=[ 7776], 99.90th=[14912], 99.95th=[14912],
| 99.99th=[14912]
lat (usec) : 250=9.25%, 500=66.00%, 750=15.00%, 1000=3.50%
lat (msec) : 2=3.50%, 4=0.75%, 10=1.75%, 20=0.25%
cpu : usr=1.65%, sys=1.65%, ctx=402, majf=0, minf=36
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 : total=r=0/w=400/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=2
Run status group 0 (all jobs):
WRITE: io=1600KB, aggrb=6584KB/s, minb=6584KB/s, maxb=6584KB/s,
mint=243msec, maxt=243msec
Disk stats (read/write):
sdb: ios=84/0, merge=0/0, ticks=92/0, in_queue=92, util=36.95%
RUN FINISHED; exit value 0; real time: 600ms; user: 40ms; system: 60ms
I darker my disk utilization here. My question is why there is no
write went tot the disk and where does those 84 reads come from?
Because in test.fio, I only issue writes to the disk /dev/sdb
