Add possibility to make sequential IO "holed"

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 5e9b390bcf3902ce8f3d4400e102f49ace9f2329..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.
        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.
 
 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
                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
 
 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
                                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
 
                        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.
 
                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).
                disabled by default.
 
 nice=int       Run the job with the given nice value. See man nice(2).


@@ -992,7 +997,8 @@ verify_backlog_batch=int    Control how many blocks fio will verify
                if verify_backlog_batch is larger than verify_backlog, some
                blocks will be verified more than once.
                
                if verify_backlog_batch is larger than verify_backlog, some
                blocks will be verified more than once.
                

-stonewall      Wait for preceeding jobs in the job file to exit, before
+stonewall
+wait_for_previous Wait for preceeding jobs in the job file to exit, before

                starting this one. Can be used to insert serialization
                points in the job file. A stone wall also implies starting
                a new reporting group.
                starting this one. Can be used to insert serialization
                points in the job file. A stone wall also implies starting
                a new reporting group.


@@ -1119,6 +1125,18 @@ disable_slat=bool Disable measurements of submission latency numbers. See
 disable_bw=bool        Disable measurements of throughput/bandwidth numbers. See
                disable_lat.
 
 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
 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