Log and dump short ios

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index a5be9dbd3e8d408bbe27491e4b15d76b30e5aa43..aeb87ddb37cc59cdd057a56bd99ea9f901efbd68 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -211,7 +211,9 @@ filename=str        Fio normally makes up a filename based on the job name,
                ioengine is file based, you can specify a number of files
                by seperating the names with a ':' colon. So if you wanted
                a job to open /dev/sda and /dev/sdb as the two working files,
-               you would use filename=/dev/sda:/dev/sdb
+               you would use filename=/dev/sda:/dev/sdb. '-' is a reserved
+               name, meaning stdin or stdout. Which of the two depends
+               on the read/write direction set.
 
 opendir=str    Tell fio to recursively add any file it can find in this
                directory and down the file system tree.
@@ -563,6 +565,14 @@ verify=str If writing to a file, fio can verify the file contents
                system to make sure that the written data is also
                correctly read back.
 
+verifysort=bool        If set, fio will sort written verify blocks when it deems
+               it faster to read them back in a sorted manner. This is
+               often the case when overwriting an existing file, since
+               the blocks are already laid out in the file system. You
+               can ignore this option unless doing huge amounts of really
+               fast IO where the red-black tree sorting CPU time becomes
+               significant.
+               
 stonewall      Wait for preceeding jobs in the job file to exit, before
                starting this one. Can be used to insert serialization
                points in the job file. A stone wall also implies starting
@@ -674,6 +684,7 @@ Client1 (g=0): err= 0:
     bw (KiB/s) : min=    0, max= 1196, per=51.00%, avg=664.02, stdev=681.68
   cpu        : usr=1.49%, sys=0.25%, ctx=7969
   IO depths    : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0%
+     issued r/w: total=0/32768, short=0/0
      lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%,
      lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0%
 
@@ -705,6 +716,8 @@ IO depths=  The distribution of io depths over the job life time. The
                16= entries includes depths up to that value but higher
                than the previous entry. In other words, it covers the
                range from 16 to 31.
+IO issued=     The number of read/write requests issued, and how many
+               of them were short.
 IO latencies=  The distribution of IO completion latencies. This is the
                time from when IO leaves fio and when it gets completed.
                The numbers follow the same pattern as the IO depths,