Add rw_sequencer option

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index b284c428dd80bad0ecdaf42c3bbfe378e5ddad13..0ef7ca42120d175c3115207861f50b964a07958e 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -313,13 +313,30 @@ rw=str            Type of io pattern. Accepted values are:
                For the mixed io types, the default is to split them 50/50.
                For certain types of io the result may still be skewed a bit,
                since the speed may be different. It is possible to specify
-               a number of IO's to do before getting a new offset - this
-               is only useful for random IO, where fio would normally
-               generate a new random offset for every IO. If you append
-               eg 8 to randread, you would get a new random offset for
+               a number of IO's to do before getting a new offset, this is
+               one by appending a ':<nr>' to the end of the string given.
+               For a random read, it would look like 'rw=randread:8' for
+               passing in an offset modifier with a value of 8. See the
+               'rw_sequencer' option.
+
+rw_sequencer=str If an offset modifier is given by appending a number to
+               the rw=<str> line, then this option controls how that
+               number modifies the IO offset being generated. Accepted
+               values are:
+
+                       sequential      Generate sequential offset
+                       identical       Generate the same offset
+
+               'sequential' is only useful for random IO, where fio would
+               normally generate a new random offset for every IO. If you
+               append eg 8 to randread, you would get a new random offset for
                every 8 IO's. The result would be a seek for only every 8
                IO's, instead of for every IO. Use rw=randread:8 to specify
-               that.
+               that. As sequential IO is already sequential, setting
+               'sequential' for that would not result in any differences.
+               'identical' behaves in a similar fashion, except it sends
+               the same offset 8 number of times before generating a new
+               offset.
 
 kb_base=int    The base unit for a kilobyte. The defacto base is 2^10, 1024.
                Storage manufacturers like to use 10^3 or 1000 as a base
@@ -1214,23 +1231,28 @@ For scripted usage where you typically want to generate tables or graphs
 of the results, fio can output the results in a semicolon separated format.
 The format is one long line of values, such as:
 
-client1;0;0;1906777;1090804;1790;0;0;0.000000;0.000000;0;0;0.000000;0.000000;929380;1152890;25.510151%;1078276.333333;128948.113404;0;0;0;0;0;0.000000;0.000000;0;0;0.000000;0.000000;0;0;0.000000%;0.000000;0.000000;100.000000%;0.000000%;324;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%;0.0%;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%
+2; client1;0;0;1906777;1090804;1790;0;0;0.000000;0.000000;0;0;0.000000;0.000000;929380;1152890;25.510151%;1078276.333333;128948.113404;0;0;0;0;0;0.000000;0.000000;0;0;0.000000;0.000000;0;0;0.000000%;0.000000;0.000000;100.000000%;0.000000%;324;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%;0.0%;100.0%;0.0%;0.0%;0.0%;0.0%;0.0%
 ;0.0%;0.0%;0.0%;0.0%;0.0%
 
-To enable terse output, use the --minimal command line option.
+To enable terse output, use the --minimal command line option. The first
+value is the version of the terse output format. If the output has to
+be changed for some reason, this number will be incremented by 1 to
+signify that change.
 
 Split up, the format is as follows:
 
-       jobname, groupid, error
+       version, jobname, groupid, error
        READ status:
                KB IO, bandwidth (KB/sec), runtime (msec)
                Submission latency: min, max, mean, deviation
                Completion latency: min, max, mean, deviation
+               Total latency: min, max, mean, deviation
                Bw: min, max, aggregate percentage of total, mean, deviation
        WRITE status:
                KB IO, bandwidth (KB/sec), runtime (msec)
                Submission latency: min, max, mean, deviation
                Completion latency: min, max, mean, deviation
+               Total latency: min, max, mean, deviation
                Bw: min, max, aggregate percentage of total, mean, deviation
        CPU usage: user, system, context switches, major faults, minor faults
        IO depths: <=1, 2, 4, 8, 16, 32, >=64