[PATCH] Add thinktime_blocks

Right now 'thinktime' waits after every IO. This may not be what you
need, sometimes you want to wait only after 'x' number of ios. This
options allows you to set the number of ios to complete, before waiting.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 1918201..c9d29f2 100644
--- a/HOWTO
+++ b/HOWTO
@@ -319,7 +319,13 @@
 
 thinktime=int	Stall the job x microseconds after an io has completed before
 		issuing the next. May be used to simulate processing being
-		done by an application.
+		done by an application. See thinktime_blocks.
+
+thinktime_blocks
+		Only valid if thinktime is set - control how many blocks
+		to issue, before waiting 'thinktime' usecs. If not set,
+		defaults to 1 which will make fio wait 'thinktime' usecs
+		after every block.
 
 rate=int	Cap the bandwidth used by this job to this number of KiB/sec.