Token-based flow control

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index c6304a7ca2ed7bf27b65df9ce844efa88f221534..da037d2b92cf18a682d13ac7210e8404a9b8e9e0 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -1231,6 +1231,25 @@ uid=int          Instead of running as the invoking user, set the user ID to
 
 gid=int                Set group ID, see uid.
 
 
 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
 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