[PATCH] Include io depth distribution statistics

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 1b34c283af0f385e00407a9167c6ec02820ad4a1..95d059e766e6399f29d8097331a076db4df29161 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -179,7 +179,10 @@ siint      SI integer. A whole number value, which may contain a postfix
 bool   Boolean. Usually parsed as an integer, however only defined for
        true and false (1 and 0).
 irange Integer range with postfix. Allows value range to be given, such
-       as 1024-4096. Also see siint.
+       as 1024-4096. A colon may also be used as the seperator, eg
+       1k:4k. If the option allows two sets of ranges, they can be
+       specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
+       siint.
 
 With the above in mind, here follows the complete list of fio job
 parameters.
@@ -211,6 +214,9 @@ rw=str              Type of io pattern. Accepted values are:
                For certain types of io the result may still be skewed a bit,
                since the speed may be different.
 
+randrepeat=bool        For random IO workloads, seed the generator in a predictable
+               way so that results are repeatable across repetitions.
+
 size=siint     The total size of file io for this job. This may describe
                the size of the single file the job uses, or it may be
                divided between the number of files in the job. If the
@@ -274,7 +280,10 @@ iodepth=int        This defines how many io units to keep in flight against
                concurrency.
 
 direct=bool    If value is true, use non-buffered io. This is usually
-               O_DIRECT. Defaults to true.
+               O_DIRECT.
+
+buffered=bool  If value is true, use buffered io. This is the opposite
+               of the 'direct' option. Defaults to true.
 
 offset=siint   Start io at the given offset in the file. The data before
                the given offset will not be touched. This effectively
@@ -344,7 +353,7 @@ startdelay=int      Start this job the specified number of seconds after fio
                jobs, and you want to delay starting some jobs to a certain
                time.
 
-timeout=int    Tell fio to terminate processing after the specified number
+runtime=int    Tell fio to terminate processing after the specified number
                of seconds. It can be quite hard to determine for how long
                a specified job will run, so this parameter is handy to
                cap the total runtime to a given time.
@@ -494,7 +503,7 @@ cpuchunks=int       If the job is a CPU cycle eater, split the load into
 fio spits out a lot of output. While running, fio will display the
 status of the jobs created. An example of that would be:
 
-Threads running: 1: [_r] [24.79% done] [ 13509/  8334 kb/s] [eta 00h:01m:31s]
+Threads: 1: [_r] [24.8% done] [ 13509/  8334 kb/s] [eta 00h:01m:31s]
 
 The characters inside the square brackets denote the current status of
 each thread. The possible values (in typical life cycle order) are:
@@ -526,10 +535,11 @@ direction, the output looks like:
 
 Client1 (g=0): err= 0:
   write: io=    32MiB, bw=   666KiB/s, runt= 50320msec
-    slat (msec): min=    0, max=  136, avg= 0.03, dev= 1.92
-    clat (msec): min=    0, max=  631, avg=48.50, dev=86.82
-    bw (KiB/s) : min=    0, max= 1196, per=51.00%, avg=664.02, dev=681.68
+    slat (msec): min=    0, max=  136, avg= 0.03, stdev= 1.92
+    clat (msec): min=    0, max=  631, avg=48.50, stdev=86.82
+    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%
 
 The client number is printed, along with the group id and error of that
 thread. Below is the io statistics, here for writes. In the order listed,
@@ -554,6 +564,11 @@ runt=              The runtime of that thread
                same disk, since they are then competing for disk access.
 cpu=           CPU usage. User and system time, along with the number
                of context switches this thread went through.
+IO depths=     The distribution of io depths over the job life time. The
+               numbers are divided into powers of 2, so for example 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.
 
 After each client has been listed, the group statistics are printed. They
 will look like this: