Add options to have fio latency profile a device

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index eb2ed25403cb8dfe2ae96e8a93d5e99aa98c8b39..044b57221f3d18c431e4840bfcbdb21bbab31b2e 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -695,6 +695,11 @@ 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.
 
+atomic=bool    If value is true, attempt to use atomic direct IO. Atomic
+               writes are guaranteed to be stable once acknowledged by
+               the operating system. Only Linux supports O_ATOMIC right
+               now.
+
 buffered=bool  If value is true, use buffered io. This is the opposite
                of the 'direct' option. Defaults to true.
 
@@ -876,6 +881,20 @@ rate_iops_min=int If fio doesn't meet this rate of IO, it will cause
                the job to exit. The same format as rate is used for read vs
                write separation.
 
+latency_target=int     If set, fio will attempt to find the max performance
+               point that the given workload will run at while maintaining a
+               latency below this target. The values is given in microseconds.
+               See latency_window and latency_percentile
+
+latency_window=int     Used with latency_target to specify the sample window
+               that the job is run at varying queue depths to test the
+               performance. The value is given in microseconds.
+
+latency_percentile=float       The percentage of IOs that must fall within the
+               criteria specified by latency_target and latency_window. If not
+               set, this defaults to 100.0, meaning that all IOs must be equal
+               or below to the value set by latency_target.
+
 max_latency=int        If set, fio will exit the job if it exceeds this maximum
                latency. It will exit with an ETIME error.