11554 Want TCP_CONGESTION socket option
Reviewed by: Yuri Pankov <yuri.pankov@nexenta.com>

@@ -148,10 +148,18 @@
      cwnd to a specified number of TCP segments.  This applies to the cases
      when the connection first starts and restarts after an idle period.  The
      process must have the PRIV_SYS_NET_CONFIG privilege if it wants to
      specify a number greater than that calculated by RFC 3390.
 
+     The operating system also provides alternative algorithms that may be
+     more appropriate for your application, including the CUBIC congestion
+     control algorithm described in RFC 8312.  These can be configured system-
+     wide using ipadm(1M), or on a per-connection basis with the TCP-level
+     socket option TCP_CONGESTION, whose argument is the name of the algorithm
+     to use (for example "cubic").  If the requested algorithm does not exist,
+     then setsockopt() will fail, and errno will be set to ENOENT.
+
    TCP Keep-Alive
      Since TCP determines whether a remote peer is no longer reachable by
      timing out waiting for acknowledgements, a host that never sends any new
      data may never notice a peer that has gone away.  While consumers can
      avoid this problem by sending their own periodic heartbeat messages