genfio: Splitting gen_template in 2 parts

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 64453489175aec0346e8e8f7df9422849582fc12..4fd025126925eb6fd75910608530b8f8c20ba27f 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -568,6 +568,8 @@ ioengine=str        Defines how the job issues io to the file. The following
 
                        vsync   Basic readv(2) or writev(2) IO.
 
+                       psyncv  Basic preadv(2) or pwritev(2) IO.
+
                        libaio  Linux native asynchronous io. Note that Linux
                                may only support queued behaviour with
                                non-buffered IO (set direct=1 or buffered=0).
@@ -766,6 +768,17 @@ random_distribution=str:float      By default, fio will use a completely uniform
                random_distribution=zipf:1.2 as the option. If a non-uniform
                model is used, fio will disable use of the random map.
 
+percentage_random=int  For a random workload, set how big a percentage should
+               be random. This defaults to 100%, in which case the workload
+               is fully random. It can be set from anywhere from 0 to 100.
+               Setting it to 0 would make the workload fully sequential. Any
+               setting in between will result in a random mix of sequential
+               and random IO, at the given percentages.
+       
+percentage_sequential=int      See percentage_random. It is guaranteed that
+               they add up to 100. The later setting has priority, each
+               will adjust the other.
+
 norandommap    Normally fio will cover every block of the file when doing
                random IO. If this option is given, fio will just get a
                new random offset without looking at past io history. This
@@ -817,11 +830,15 @@ thinktime_spin=int
                to sleeping for the rest of the period specified by
                thinktime.
 
-thinktime_blocks
+thinktime_blocks=int
                Only valid if thinktime is set - control how many blocks
                to issue, before waiting 'thinktime' usecs. If not set,
                defaults to 1 which will make fio wait 'thinktime' usecs
-               after every block.
+               after every block. This effectively makes any queue depth
+               setting redundant, since no more than 1 IO will be queued
+               before we have to complete it and do our thinktime. In
+               other words, this setting effectively caps the queue depth
+               if the latter is larger.
 
 rate=int       Cap the bandwidth used by this job. The number is in bytes/sec,
                the normal suffix rules apply. You can use rate=500k to limit
@@ -1219,7 +1236,7 @@ write_lat_log=str Same as write_bw_log, except that this option stores io
 
                write_lat_log=foo
 
-               The actual log names will be foo_slat.log, foo_slat.log,
+               The actual log names will be foo_slat.log, foo_clat.log,
                and foo_lat.log. This helps fio_generate_plot fine the logs
                automatically.
 
@@ -1244,10 +1261,12 @@ lockmem=int     Pin down the specified amount of memory with mlock(2). Can
                The amount specified is per worker.
 
 exec_prerun=str        Before running this job, issue the command specified
-               through system(3).
+               through system(3). Output is redirected in a file called
+               jobname.prerun.txt.
 
 exec_postrun=str After the job completes, issue the command specified
-                though system(3).
+                though system(3). Output is redirected in a file called
+                jobname.postrun.txt.
 
 ioscheduler=str        Attempt to switch the device hosting the file to the specified
                io scheduler before running.