Be safe and re-prep requeue io_u's

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 198d70b5247229402e76c1d22d6b304b37cfffb5..8e6e29bbc7dd98e6eb9857596c02de03ebdd0635 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -49,7 +49,7 @@ bottom, it contains the following basic parameters:
 
        IO engine       How do we issue io? We could be memory mapping the
                        file, we could be using regular read/write, we
 
        IO engine       How do we issue io? We could be memory mapping the
                        file, we could be using regular read/write, we

-                       could be using splice, async io, or even
+                       could be using splice, async io, syslet, or even

                        SG (SCSI generic sg).
 
        IO depth        If the io engine is async, how large a queuing
                        SG (SCSI generic sg).
 
        IO depth        If the io engine is async, how large a queuing


@@ -193,13 +193,19 @@ name=str  ASCII name of the job. This may be used to override the
                special purpose of also signaling the start of a new
                job.
 
                special purpose of also signaling the start of a new
                job.
 

+description=str        Text description of the job. Doesn't do anything except
+               dump this text description when this job is run. It's
+               not parsed.
+

 directory=str  Prefix filenames with this directory. Used to places files
                in a different location than "./".
 
 filename=str   Fio normally makes up a filename based on the job name,
                thread number, and file number. If you want to share
                files between threads in a job or several jobs, specify
 directory=str  Prefix filenames with this directory. Used to places files
                in a different location than "./".
 
 filename=str   Fio normally makes up a filename based on the job name,
                thread number, and file number. If you want to share
                files between threads in a job or several jobs, specify

-               a filename for each of them to override the default.
+               a filename for each of them to override the default. If
+               the ioengine used is 'net', the filename is the host and
+               port to connect to in the format of =host:port.

 
 rw=str         Type of io pattern. Accepted values are:
 
 
 rw=str         Type of io pattern. Accepted values are:
 


@@ -264,6 +270,9 @@ ioengine=str        Defines how the job issues io to the file. The following
                                vmsplice(2) to transfer data from user
                                space to the kernel.
 
                                vmsplice(2) to transfer data from user
                                space to the kernel.
 

+                       syslet-rw Use the syslet system calls to make
+                               regular read/write async.
+

                        sg      SCSI generic sg v3 io. May either be
                                synchronous using the SG_IO ioctl, or if
                                the target is an sg character device
                        sg      SCSI generic sg v3 io. May either be
                                synchronous using the SG_IO ioctl, or if
                                the target is an sg character device


@@ -274,6 +283,12 @@ ioengine=str       Defines how the job issues io to the file. The following
                                to. This is mainly used to exercise fio
                                itself and for debugging/testing purposes.
 
                                to. This is mainly used to exercise fio
                                itself and for debugging/testing purposes.
 

+                       net     Transfer over the network to given host:port.
+                               'filename' must be set appropriately to
+                               filename=host:port regardless of send
+                               or receive, if the latter only the port
+                               argument is used.
+

 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
 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


@@ -328,7 +343,14 @@ 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
 
 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
 
 thinktime_blocks
                Only valid if thinktime is set - control how many blocks


@@ -541,6 +563,8 @@ 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%
     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%

 
 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,
 
 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,


@@ -570,6 +594,12 @@ IO depths= The distribution of io depths over the job life time. The
                16= entries includes depths up to that value but higher
                than the previous entry. In other words, it covers the
                range from 16 to 31.
                16= entries includes depths up to that value but higher
                than the previous entry. In other words, it covers the
                range from 16 to 31.

+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.

 
 After each client has been listed, the group statistics are printed. They
 will look like this:
 
 After each client has been listed, the group statistics are printed. They
 will look like this: