posixaio engine: residual data count

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index ea98810a211d97328232dfb593f84654cfa2f331..06408e40e16a91fadeea2dce399efc444845b6e5 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -253,6 +253,14 @@ bs_unaligned       If this option is given, any byte size value within bsrange
 
 nrfiles=int    Number of files to use for this job. Defaults to 1.
 
+file_service_type=str  Defines how fio decides which file from a job to
+               service next. The following types are defined:
+
+                       random  Just choose a file at random.
+
+                       roundrobin  Round robin over open files. This
+                               is the default.
+
 ioengine=str   Defines how the job issues io to the file. The following
                types are defined:
 
@@ -289,11 +297,20 @@ 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.
@@ -570,8 +587,8 @@ 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,
@@ -605,8 +622,8 @@ 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: