X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=745e9c72906a378fe1c5fb3818b3ab139834d633;hp=ac15fc800f150d61d82d5f278dc3078cc8b0b296;hb=780bf1a192f494dcbacb9c1fcc75f6c440a7051e;hpb=65db0851e8cd98c61e029e64db7038f92ad9ae02

diff --git a/HOWTO b/HOWTO
index ac15fc80..745e9c72 100644
--- a/HOWTO
+++ b/HOWTO
@@ -289,11 +289,27 @@ ioengine=str	Defines how the job issues io to the file. The following
 				or receive, if the latter only the port
 				argument is used.
 
+			external Prefix to specify loading an external
+				IO engine object file. Append the engine
+				filename, eg ioengine=external:/tmp/foo.o
+				to load ioengine foo.o in /tmp.
+
 iodepth=int	This defines how many io units to keep in flight against
 		the file. The default is 1 for each file defined in this
 		job, can be overridden with a larger value for higher
 		concurrency.
 
+iodepth_batch=int This defines how many pieces of IO to submit at once.
+		It defaults to the same as iodepth, but can be set lower
+		if one so desires.
+
+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.
 
@@ -563,8 +579,8 @@ 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,
@@ -598,8 +614,8 @@ 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: