Add possibility to make sequential IO "holed"

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 88bd5e6c14f0f1ff356fbab964fd0a12a0a63c61..a1b2e8c0bf7a6f51bceb8016618acb32e7dae01e 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -244,6 +244,7 @@ irange      Integer range with suffix. Allows value range to be given, such
        1k:4k. If the option allows two sets of ranges, they can be
        specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
        int.
+float_list     A list of floating numbers, separated by a ':' character.
 
 With the above in mind, here follows the complete list of fio job
 parameters.
@@ -318,8 +319,12 @@ rw=str             Type of io pattern. Accepted values are:
                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.
+               passing in an offset modifier with a value of 8. If the
+               postfix is used with a sequential IO pattern, then the value
+               specified will be added to the generated offset for each IO.
+               For instance, using rw=write:4k will skip 4k for every
+               write. It turns sequential IO into sequential IO with holes.
+               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
@@ -569,9 +574,9 @@ ioengine=str        Defines how the job issues io to the file. The following
                                for more info on GUASI.
 
                        rdma    The RDMA I/O engine  supports  both  RDMA
-                               memory semantic(RDMA_WRITE/RDMA_READ) and
-                               channel semantic(Send/Recv) in InfiniBand, RoCE
-                               and iWarp environment.
+                               memory semantics (RDMA_WRITE/RDMA_READ) and
+                               channel semantics (Send/Recv) for the
+                               InfiniBand, RoCE and iWARP protocols.
 
                        external Prefix to specify loading an external
                                IO engine object file. Append the engine
@@ -678,10 +683,10 @@ norandommap       Normally fio will cover every block of the file when doing
                blocksizes (via bsrange=) are used, since fio only tracks
                complete rewrites of blocks.
 
-softrandommap  See norandommap. If fio runs with the random block map enabled
-               and it fails to allocate the map, if this option is set it
-               will continue without a random block map. As coverage will
-               not be as complete as with random maps, this option is
+softrandommap=bool See norandommap. If fio runs with the random block map
+               enabled and it fails to allocate the map, if this option is
+               set it will continue without a random block map. As coverage
+               will not be as complete as with random maps, this option is
                disabled by default.
 
 nice=int       Run the job with the given nice value. See man nice(2).
@@ -1120,6 +1125,18 @@ disable_slat=bool Disable measurements of submission latency numbers. See
 disable_bw=bool        Disable measurements of throughput/bandwidth numbers. See
                disable_lat.
 
+clat_percentiles=bool Enable the reporting of percentiles of
+                completion latencies.
+
+percentile_list=float_list Overwrite the default list of percentiles
+               for completion latencies. Each number is a floating
+               number in the range (0,100], and the maximum length of
+               the list is 20. Use ':' to separate the numbers, and
+               list the numbers in ascending order. For example,
+               --percentile_list=99.5:99.9 will cause fio to report
+               the values of completion latency below which 99.5% and
+               99.9% of the observed latencies fell, respectively.
+
 gtod_reduce=bool Enable all of the gettimeofday() reducing options
                (disable_clat, disable_slat, disable_bw) plus reduce
                precision of the timeout somewhat to really shrink