Private parameters for ioengines
Here is the polished version of the engine private options patch. As
discussed, the global section only ever tracks the private options for
the globally defined ioengine. For command line parameters, the
ioengine must be selected before any private options are used. (IE
--ioengine=libaio --userspace_reap will work, but --userspace_reap
--ioengine=libaio will not.)
The userspace_reap option from libaio has been moved over to this new
option method, usage should be identical to before.
The net ioengine has been modified to use parameters, with hostname,
port, protocol and listen defined as ioengine private parameters. The
old style of hostname=host,port,protocol no longer works, so usage
will need to be updated. (It will spit out an error that should be
clear enough that it changed if this is tried.) Also, with the new
way for specifying parameters, the net IO engine now allows data to
flow in either direction on TCP connections, regardless of which end
initiates the connection.
There's also a new command line argument --enghelp which can be used
to get help on ioengine private parameters, similar to --cmdhelp.
With no argument, it lists all built-in ioengine. The argument is an
ioengine name (Or path to .so) and optionally a comma followed by a
command name, which behaves identically to --cmdhelp.
For ioengine authorship, if options are supplied, both the options
structure and the size of the storage needed must be supplied, and the
storage must be large enough to hold a pointer to struct thread_data;
that is because the options callback doesn't explicitly have a pointer
to the thread data (Normally it relies on the fact that the options
struct is the start of the thread data), so the offset 0 of the struct
must point to the thread data, and is filled in automatically. (This
also neatly provides a guarantee that offset 0 is reserved in the
options data, so it can be safely used as a test of undefined.)
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/HOWTO b/HOWTO
index 41edcf1..2403a5c 100644
--- a/HOWTO
+++ b/HOWTO
@@ -524,16 +524,7 @@
libaio Linux native asynchronous io. Note that Linux
may only support queued behaviour with
non-buffered IO (set direct=1 or buffered=0).
- This engine also has a sub-option,
- userspace_reap. To set it, use
- ioengine=libaio:userspace_reap. Normally, with
- the libaio engine in use, fio will use the
- io_getevents system call to reap newly returned
- events. With this flag turned on, the AIO ring
- will be read directly from user-space to reap
- events. The reaping mode is only enabled when
- polling for a minimum of 0 events (eg when
- iodepth_batch_complete=0).
+ This engine defines engine specific options.
posixaio glibc posix asynchronous io.
@@ -562,16 +553,16 @@
itself and for debugging/testing purposes.
net Transfer over the network to given host:port.
- 'filename' must be set appropriately to
- filename=host/port/protocol regardless of send
- or receive, if the latter only the port
- argument is used. 'host' may be an IP address
- or hostname, port is the port number to be used,
- and protocol may be 'udp' or 'tcp'. If no
- protocol is given, TCP is used.
+ Depending on the protocol used, the hostname,
+ port, listen and filename options are used to
+ specify what sort of connection to make, while
+ the protocol option determines which protocol
+ will be used.
+ This engine defines engine specific options.
netsplice Like net, but uses splice/vmsplice to
map data and send/receive.
+ This engine defines engine specific options.
cpuio Doesn't transfer any data, but burns CPU
cycles according to the cpuload= and
@@ -1210,6 +1201,45 @@
gid=int Set group ID, see uid.
+In addition, there are some parameters which are only valid when a specific
+ioengine is in use. These are used identically to normal parameters, with the
+caveat that when used on the command line, they must come after the ioengine
+that defines them is selected.
+
+[libaio] userspace_reap Normally, with the libaio engine in use, fio will use
+ the io_getevents system call to reap newly returned events.
+ With this flag turned on, the AIO ring will be read directly
+ from user-space to reap events. The reaping mode is only
+ enabled when polling for a minimum of 0 events (eg when
+ iodepth_batch_complete=0).
+
+[netsplice] hostname=str
+[net] hostname=str The host name or IP address to use for TCP or UDP based IO.
+ If the job is a TCP listener or UDP reader, the hostname is not
+ used and must be omitted.
+
+[netsplice] port=int
+[net] port=int The TCP or UDP port to bind to or connect to.
+
+[netsplice] protocol=str
+[netsplice] proto=str
+[net] protocol=str
+[net] proto=str The network protocol to use. Accepted values are:
+
+ tcp Transmission control protocol
+ udp Unreliable datagram protocol
+ unix UNIX domain socket
+
+ When the protocol is TCP or UDP, the port must also be given,
+ as well as the hostname if the job is a TCP listener or UDP
+ reader. For unix sockets, the normal filename option should be
+ used and the port is invalid.
+
+[net] listen For TCP network connections, tell fio to listen for incoming
+ connections rather than initiating an outgoing connection. The
+ hostname must be omitted if this option is used.
+
+
6.0 Interpreting the output
---------------------------