====== fio ======
---- dataentry benchmark ----
name           : fio
layers_ttags     : POSIX
features_ttags : data, programmable
parallel_ttags : pthreads
type_ttags     : synthetic
license_ttag   : GPLv2
webpage_url    : http://git.kernel.dk/?p=fio.git
----

Fio is a multithread capable io-performance testing tool.

===== Usage =====

There are a number of comandline options to modify the behavior of the test.

Here are a few important ones:
  * ''--rw=MODE'' lets you specify your workload
    *  ''write'' sequential writes
    *  ''read'' sequential reads
    *  ''rw'' sequential reads and writes (default 50/50)
  * ''--name=FILE'' name of the job
  * ''--size=BYTES'' size of the I/O for the job
  * ''--bs=BYTES'' block size
  * ''--direct=BOOL'' Buffered(true) or non buffered(false) I/O
  * ''--numjobs=NUMBER'' number of threads
  * ''--group_reporting'' display the result of a group instead of every thread

===== Example Output =====
For example runnning fio --rw=rw --name=testfile --size=128M --bs=128K --direct=1 --numjobs=4 --group_reporting results in the following output
<code>
1+0 records in                                                              
1+0 records out                                          
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 9.50512 s, 113 MB/s
</code>

Running dd if=/dev/zero of=test bs=512 count=2048 oflag=dsync will give you an rough idea about the latency and result in a output like this:
<code>
testfile: (g=0): rw=rw, bs=(R) 128KiB-128KiB, (W) 128KiB-128KiB, (T) 128KiB-128KiB, ioengine=psync, iodepth=1
...
fio-2.19
Starting 4 processes
Jobs: 2 (f=2): [_(2),M(2)][100.0%][r=35.7MiB/s,w=36.9MiB/s][r=285,w=295 IOPS][eta 00m:00s]
testfile: (groupid=0, jobs=4): err= 0: pid=3213: Thu May 11 14:36:41 2017
   read: IOPS=227, BW=28.5MiB/s (29.9MB/s)(261MiB/9167msec)
    clat (usec): min=554, max=532949, avg=11901.95, stdev=36977.09
     lat (usec): min=555, max=532950, avg=11902.44, stdev=36977.09
    clat percentiles (usec):
     |  1.00th=[  572],  5.00th=[  636], 10.00th=[  780], 20.00th=[ 1128],
     | 30.00th=[ 1224], 40.00th=[ 1336], 50.00th=[ 1448], 60.00th=[ 1656],
     | 70.00th=[ 2672], 80.00th=[ 7712], 90.00th=[25984], 95.00th=[62208],
     | 99.00th=[199680], 99.50th=[261120], 99.90th=[444416], 99.95th=[477184],
     | 99.99th=[536576]
  write: IOPS=219, BW=27.5MiB/s (28.8MB/s)(251MiB/9167msec)
    clat (usec): min=572, max=941129, avg=5394.03, stdev=30216.75
     lat (usec): min=581, max=941134, avg=5404.25, stdev=30216.74
    clat percentiles (usec):
     |  1.00th=[  676],  5.00th=[  788], 10.00th=[  876], 20.00th=[ 1272],
     | 30.00th=[ 1400], 40.00th=[ 1496], 50.00th=[ 1560], 60.00th=[ 1784],
     | 70.00th=[ 2128], 80.00th=[ 3280], 90.00th=[ 8640], 95.00th=[15040],
     | 99.00th=[64768], 99.50th=[108032], 99.90th=[171008], 99.95th=[831488],
     | 99.99th=[937984]
    lat (usec) : 750=6.25%, 1000=5.57%
    lat (msec) : 2=53.86%, 4=12.33%, 10=9.50%, 20=4.86%, 50=3.74%
    lat (msec) : 100=2.12%, 250=1.39%, 500=0.32%, 750=0.02%, 1000=0.05%
  cpu          : usr=0.09%, sys=0.48%, ctx=4118, majf=0, minf=47
  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 rwt: total=2087,2009,0, short=0,0,0, dropped=0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=1

Run status group 0 (all jobs):
   READ: bw=28.5MiB/s (29.9MB/s), 28.5MiB/s-28.5MiB/s (29.9MB/s-29.9MB/s), io=261MiB (274MB), run=9167-9167msec
  WRITE: bw=27.5MiB/s (28.8MB/s), 27.5MiB/s-27.5MiB/s (28.8MB/s-28.8MB/s), io=251MiB (263MB), run=9167-9167msec

Disk stats (read/write):
  sda: ios=2075/2001, merge=0/6, ticks=24774/11073, in_queue=35846, util=99.05%
</code>