genfio: Splitting gen_template in 2 parts

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index c7d0c9e8324b646a637ee9d55e9ebd273a6119a1..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.
@@ -1600,6 +1619,9 @@ util=             The disk utilization. A value of 100% means we kept the disk
 
 It is also possible to get fio to dump the current output while it is
 running, without terminating the job. To do that, send fio the USR1 signal.
+You can also get regularly timed dumps by using the --status-interval
+parameter, or by creating a file in /tmp named fio-dump-status. If fio
+sees this file, it will unlink it and dump the current output status.
 
 
 7.0 Terse output
@@ -1721,7 +1743,7 @@ trim       trim the given file from the given 'offset' for 'length' bytes
 
 
 9.0 CPU idleness profiling
-
+--------------------------
 In some cases, we want to understand CPU overhead in a test. For example,
 we test patches for the specific goodness of whether they reduce CPU usage.
 fio implements a balloon approach to create a thread per CPU that runs at