[PATCH] rusage stat

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 2616156d1234017a1d08da368c3bb461c29fcf0a..a5caea3db7a6201d74311b50a5d5d56bbbb77311 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -218,22 +218,22 @@ size=siint        The total size of file io for this job. This may describe
                size if larger than the current file size. If this parameter
                is not given and the file exists, the file size will be used.
 
-bs=siint       The block size used for the io units. Defaults to 4k.
-
-read_bs=siint
-write_bs=siint If the workload is a mixed read-write workload, you can use
-               these options to set separate block sizes.
+bs=siint       The block size used for the io units. Defaults to 4k. Values
+               can be given for both read and writes. If a single siint is
+               given, it will apply to both. If a second siint is specified
+               after a comma, it will apply to writes only. In other words,
+               the format is either bs=read_and_write or bs=read,write.
+               bs=4k,8k will thus use 4k blocks for reads, and 8k blocks
+               for writes. If you only wish to set the write size, you
+               can do so by passing an empty read size - bs=,8k will set
+               8k for writes and leave the read default value.
 
 bsrange=irange Instead of giving a single block size, specify a range
                and fio will mix the issued io block sizes. The issued
                io unit will always be a multiple of the minimum value
-               given (also see bs_unaligned).
-
-read_bsrange=irange
-write_bsrange=irange
-               If the workload is a mixed read-write workload, you can use
-               one of these options to set separate block size ranges for
-               reads and writes.
+               given (also see bs_unaligned). Applies to both reads and
+               writes, however a second range can be given after a comma.
+               See bs=.
 
 bs_unaligned   If this option is given, any byte size value within bsrange
                may be used as a block range. This typically wont work with
@@ -264,6 +264,10 @@ ioengine=str       Defines how the job issues io to the file. The following
                                we use read(2) and write(2) for asynchronous
                                io.
 
+                       null    Doesn't transfer any data, just pretends
+                               to. This is mainly used to exercise fio
+                               itself and for debugging/testing purposes.
+
 iodepth=int    This defines how many io units to keep in flight against
                the file. The default is 1 for each file defined in this
                job, can be overridden with a larger value for higher