Just want to seek some advice as this is driving me crazy and I have a
deadline fast approaching so I am not sure if I can completely change
course at this point.
So here's the situation - it looks like different run of fio is giving
me different output. The outputs are mutating (reproducible) on me so
it broken my parser and more importantly, my data because I depend on
"Completion latency" ('clat') for my calculation. Ugh. Maybe if I
use '--minimal' during the run, it might be better but I am too commit
to change at this point.
Note below: the 'clat (usec): min=...' line is missing from the first run.
Here's are run examples:
(1st run example)
===
{mydisk}- {myrw}- {myiodepth}- {myblocksize}
/dev/sdb-randrw-32-1024K
===
mytest: (g=0): rw=randrw, bs=1M-1M/1M-1M/1M-1M, ioengine=libaio, iodepth=32
fio-2.1
Starting 1 process
mytest: (groupid=0, jobs=1): err= 0: pid=24678: Thu Sep 12 18:24:13 2013
read : io=1058.0MB, bw=169095KB/s, iops=165, runt= 6407msec
slat (usec): min=83, max=327, avg=122.89, stdev=12.20 <-- (### My
comment ###) - What happened to 'clat' and 'lat' after this line? See
2nd run example where the lines are there.
clat percentiles (usec):
| 1.00th=[ 0], 5.00th=[ 0], 10.00th=[ 0], 20.00th=[ 0],
(2nd run example)
===
{mydisk}- {myrw}- {myiodepth}- {myblocksize}
/dev/sdb-randrw-32-64K
===
mytest: (g=0): rw=randrw, bs=64K-64K/64K-64K/64K-64K, ioengine=libaio,
iodepth=32
fio-2.1
Starting 1 process
mytest: (groupid=0, jobs=1): err= 0: pid=24344: Thu Sep 12 18:19:41 2013
read : io=1308.9MB, bw=76522KB/s, iops=1194, runt= 17515msec
slat (usec): min=10, max=205, avg=13.91, stdev= 2.69
clat (usec): min=867, max=31655, avg=14835.72, stdev=3382.80 <--
(### My comment ###) - This line is missing from above
lat (usec): min=887, max=31671, avg=14849.32, stdev=3382.55 <--
(### My comment ###) - This line is missing from above
clat percentiles (usec):
| 1.00th=[ 8384], 5.00th=[ 9664], 10.00th=[10560], 20.00th=[11712],
Keeping everything constant, the different is different on higher
blocksize - this is reproducible. Any suggestion / advice here?
Here's my fio template - I am looping thru different values for $myrw,
$mydisk, $myblocksize:
[mytest]
rw=${myrw}
filename=${mydisk}
size=2G
iodepth=${myiodepth}
bs=${myblocksize}
ioengine=libaio
ramp_time=10s
direct=1
end_fsync=0
invalidate=1
Brian L.
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