New offset_increment option

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index c6304a7ca2ed7bf27b65df9ce844efa88f221534..30e40593a28e59bd87b955c58acf4751b6d3def3 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -627,6 +627,7 @@ iodepth_low=int     The low water mark indicating when to start filling
 
 direct=bool    If value is true, use non-buffered io. This is usually
                O_DIRECT. Note that ZFS on Solaris doesn't support direct io.
+               On Windows the synchronous ioengines don't support direct io.
 
 buffered=bool  If value is true, use buffered io. This is the opposite
                of the 'direct' option. Defaults to true.
@@ -635,6 +636,13 @@ offset=int Start io at the given offset in the file. The data before
                the given offset will not be touched. This effectively
                caps the file size at real_size - offset.
 
+offset_increment=int   If this is provided, then the real offset becomes
+               the offset + offset_increment * thread_number, where the
+               thread number is a counter that starts at 0 and is incremented
+               for each job. This option is useful if there are several jobs
+               which are intended to operate on a file in parallel in disjoint
+               segments, with even spacing between the starting points.
+
 fsync=int      If writing to a file, issue a sync of the dirty data
                for every number of blocks given. For example, if you give
                32 as a parameter, fio will sync the file for every 32
@@ -644,7 +652,7 @@ fsync=int   If writing to a file, issue a sync of the dirty data
 
 fdatasync=int  Like fsync= but uses fdatasync() to only sync data and not
                metadata blocks.
-               In FreeBSD there is no fdatasync(), this falls back to
+               In FreeBSD and Windows there is no fdatasync(), this falls back to
                using fsync()
 
 sync_file_range=str:val        Use sync_file_range() for every 'val' number of
@@ -1231,6 +1239,25 @@ uid=int          Instead of running as the invoking user, set the user ID to
 
 gid=int                Set group ID, see uid.
 
+flow_id=int    The ID of the flow. If not specified, it defaults to being a
+               global flow. See flow.
+
+flow=int       Weight in token-based flow control. If this value is used, then
+               there is a 'flow counter' which is used to regulate the
+               proportion of activity between two or more jobs. fio attempts
+               to keep this flow counter near zero. The 'flow' parameter
+               stands for how much should be added or subtracted to the flow
+               counter on each iteration of the main I/O loop. That is, if
+               one job has flow=8 and another job has flow=-1, then there
+               will be a roughly 1:8 ratio in how much one runs vs the other.
+
+flow_watermark=int     The maximum value that the absolute value of the flow
+               counter is allowed to reach before the job must wait for a
+               lower value of the counter.
+
+flow_sleep=int The period of time, in microseconds, to wait after the flow
+               watermark has been exceeded before retrying operations
+
 In addition, there are some parameters which are only valid when a specific
 ioengine is in use. These are used identically to normal parameters, with the
 caveat that when used on the command line, they must come after the ioengine