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diff --git a/HOWTO b/HOWTO
index f61b4c1d..237b3ad2 100644
--- a/HOWTO
+++ b/HOWTO
@@ -108,8 +108,8 @@ to use any ascii name you want, except 'global' which has special meaning.
 A global section sets defaults for the jobs described in that file. A job
 may override a global section parameter, and a job file may even have
 several global sections if so desired. A job is only affected by a global
-section residing above it. If the first character in a line is a ';', the
-entire line is discarded as a comment.
+section residing above it. If the first character in a line is a ';' or a
+'#', the entire line is discarded as a comment.
 
 So lets look at a really simple job file that define to threads, each
 randomly reading from a 128MiB file.
@@ -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.
 
+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.
 
@@ -343,7 +350,14 @@ prioclass=int	Set the io priority class. See man ionice(1).
 
 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. See thinktime_blocks.
+		done by an application. See thinktime_blocks and
+		thinktime_spin.
+
+thinktime_spin=int
+		Only valid if thinktime is set - pretend to spend CPU time
+		doing something with the data received, before falling back
+		to sleeping for the rest of the period specified by
+		thinktime.
 
 thinktime_blocks
 		Only valid if thinktime is set - control how many blocks
@@ -556,8 +570,8 @@ Client1 (g=0): err= 0:
     bw (KiB/s) : min=    0, max= 1196, per=51.00%, avg=664.02, stdev=681.68
   cpu        : usr=1.49%, sys=0.25%, ctx=7969
   IO depths    : 1=0.1%, 2=0.3%, 4=0.5%, 8=99.0%, 16=0.0%, 32=0.0%, >32=0.0%
-     lat (msec): 2=1.6%, 4=0.0%, 8=3.2%, 16=12.8%, 32=38.4%, 64=24.8%, 128=15.2%
-     lat (msec): 256=4.0%, 512=0.0%, 1024=0.0%, >=2048=0.0%
+     lat (msec): 2=1.6%, 4=0.0%, 10=3.2%, 20=12.8%, 50=38.4%, 100=24.8%,
+     lat (msec): 250=15.2%, 500=0.0%, 750=0.0%, 1000=0.0%, >=2048=0.0%
 
 The client number is printed, along with the group id and error of that
 thread. Below is the io statistics, here for writes. In the order listed,
@@ -591,8 +605,8 @@ IO latencies=	The distribution of IO completion latencies. This is the
 		time from when IO leaves fio and when it gets completed.
 		The numbers follow the same pattern as the IO depths,
 		meaning that 2=1.6% means that 1.6% of the IO completed
-		within 2 msecs, 16=12.8% means that 12.8% of the IO
-		took more than 8 msecs, but less than (or equal to) 16 msecs.
+		within 2 msecs, 20=12.8% means that 12.8% of the IO
+		took more than 10 msecs, but less than (or equal to) 20 msecs.
 
 After each client has been listed, the group statistics are printed. They
 will look like this: