Recent feature detection changes have gotten the -C (TCP congestion

algorithm selection) option to work on FreeBSD for free, starting with
FreeBSD 9.  Update various documentation places to note this.  One
specifies the congestion algorithm in the same was on Linux, although
the names of the algorithms are (at least in the general case) different.
"sysctl net.inet.tcp.cc" on FreeBSD provides a list of available
algorithms, which are implemented as loadable kernel modules.

Rename the --linux-congestion long option to --congestion (retaining
the old option as a deprecated synonym).

src/iperf3.1

@@ -149,8 +149,11 @@ period.
 .BR -T ", " --title " \fIstr\fR"
 Prefix every output line with this string.
 .TP
-.BR -C ", " --linux-congestion " \fIalgo\fR"
-Set the congestion control algorithm (linux only).
+.BR -C ", " --congestion " \fIalgo\fR"
+Set the congestion control algorithm (Linux and FreeBSD only).  An
+older
+.B --linux-congestion
+synonym for this flag is accepted but is deprecated.
 
 .SH AUTHORS
 Iperf was originally written by Mark Gates and Alex Warshavsky.

src/iperf_api.c

@@ -574,6 +574,7 @@ iperf_parse_arguments(struct iperf_test *test, int argc, char **argv)
 #endif /* HAVE_CPU_AFFINITY */
         {"title", required_argument, NULL, 'T'},
 #if defined(HAVE_TCP_CONGESTION)
+        {"congestion", required_argument, NULL, 'C'},
         {"linux-congestion", required_argument, NULL, 'C'},
 #endif /* HAVE_TCP_CONGESTION */
 #if defined(HAVE_SCTP)

src/locale.c

@@ -106,7 +106,7 @@ const char usage_longstr[] = "Usage: iperf [-s|-c host] [options]\n"
                            "  -w, --window    #[KMG]    TCP window size (socket buffer size)\n"
                            "  -B, --bind      <host>    bind to a specific interface\n"
 #if defined(HAVE_TCP_CONGESTION)
-                           "  -C, --linux-congestion <algo>  set TCP congestion control algorithm (Linux only)\n"
+                           "  -C, --congestion <algo>   set TCP congestion control algorithm (Linux and FreeBSD only)\n"
 #endif /* HAVE_TCP_CONGESTION */
                            "  -M, --set-mss   #         set TCP maximum segment size (MTU - 40 bytes)\n"
                            "  -N, --nodelay             set TCP no delay, disabling Nagle's Algorithm\n"