Add low water mark for queuing depth

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index ac15fc800f150d61d82d5f278dc3078cc8b0b296..ea98810a211d97328232dfb593f84654cfa2f331 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -294,6 +294,13 @@ iodepth=int        This defines how many io units to keep in flight against
                job, can be overridden with a larger value for higher
                concurrency.
 
                job, can be overridden with a larger value for higher
                concurrency.
 

+iodepth_low=int        The low water mark indicating when to start filling
+               the queue again. Defaults to the same as iodepth, meaning
+               that fio will attempt to keep the queue full at all times.
+               If iodepth is set to eg 16 and iodepth_low is set to 4, then
+               after fio has filled the queue of 16 requests, it will let
+               the depth drain down to 4 before starting to fill it again.
+

 direct=bool    If value is true, use non-buffered io. This is usually
                O_DIRECT.
 
 direct=bool    If value is true, use non-buffered io. This is usually
                O_DIRECT.