doc: Add zero:// manpage

src/channel/meson.build

@@ -39,6 +39,7 @@ mansources = [
 	'common.rst',
 	'tcp.rst',
 	'udp.rst',
+	'zero.rst',
 	]
 
 foreach f : mansources

src/channel/zero.rst

@@ -0,0 +1,52 @@
+tll-channel-zero
+================
+
+:Manual Section: 7
+:Manual Group: TLL
+:Subtitle: Zeroed message generator channel
+
+Synopsis
+--------
+
+``zero://;size=<size>;msgid=<integer>``
+
+Description
+-----------
+
+Channel implements generator that is always ready to provide message, like ``/dev/zero`` special
+device. On each ``tll_channel_process`` message callback is invoked. Signalling file descriptor (if
+not disabled with ``fd=no``) is always ready.
+
+This channel is mostly useful in benchmarks or transport load tests.  Each time same message is
+passed to callback so runtime overhead is minimal - process call takes only several nanoseconds
+(depening on machine) so reading from this channel can give hundreds of millions of messages per
+second.
+
+Init parameters
+~~~~~~~~~~~~~~~
+
+``size=<size>`` (default ``1kb``) - size of generated message.
+
+``msgid=<int>`` (default ``0``) - id of generated message.
+
+``fill=<int8>`` (default ``0``) - fill character used to memset message body.
+
+``pending=<bool>`` (default ``true``) - disable pending dynamic flag. Useful to test performance of
+processing loop in different scenarios.
+
+Examples
+--------
+
+Generate stream of messages with id 10 of size 256:
+
+::
+
+    zero://;size=256b;msgid=10
+
+See also
+--------
+
+``tll-channel-common(7)``
+
+..
+    vim: sts=4 sw=4 et tw=100