Merge pull request #96 from nealcardwell/master

Add  neper --congestion-control option to set TCP congestion control algorithm

Author: hi-rajat-kumar

common.c

@@ -233,6 +233,12 @@ void set_tcp_tx_delay(int fd, int delay, struct callbacks *cb)
                 PLOG_ERROR(cb, "setsockopt(TCP_TX_DELAY)");
 }
 
+void set_congestion_control(int fd, const char *cc, struct callbacks *cb)
+{
+        if (setsockopt(fd, SOL_TCP, TCP_CONGESTION, cc, strlen(cc)))
+                PLOG_ERROR(cb, "setsockopt(TCP_CONGESTION)");
+}
+
 void set_tcp_no_delay(int fd, struct callbacks *cb)
 {
         int value = true;

common.h

@@ -157,6 +157,7 @@ void set_freebind(int fd, struct callbacks *cb);
 void set_debug(int fd, int onoff, struct callbacks *cb);
 void set_mark(int fd, int mark, struct callbacks *cb);
 void set_tcp_tx_delay(int fd, int delay, struct callbacks *cb);
+void set_congestion_control(int fd, const char *cc, struct callbacks *cb);
 void set_tcp_no_delay(int fd, struct callbacks *cb);
 void fill_random(char *buf, int size);
 int do_close(int fd);

define_all_flags.c

@@ -72,6 +72,7 @@ struct flags_parser *add_flags_tcp(struct flags_parser *fp)
 #endif
         DEFINE_FLAG(fp, int,          tcp_tx_delay,   0,      't', "Force usec delay in TCP flows");
         DEFINE_FLAG(fp, bool,         no_delay,       false,   0,  "Set TCP_NODELAY sockopt on data sockets to disable Nagle's algorithm");
+        DEFINE_FLAG(fp, const char *, congestion_control, NULL,  0,  "TCP congestion control algorithm to control connection sending rate");
 
         /* Return the updated fp */
         return (fp);

lib.h

@@ -96,6 +96,7 @@ struct options {
         bool time_wait;
         double interval;
         long long max_pacing_rate;
+        const char *congestion_control;
         const char *local_hosts;
         const char *host;
         const char *control_port;

socket.c

@@ -80,6 +80,8 @@ static void socket_init_established(struct thread *t, int s)
                 uint64_t m = opts->max_pacing_rate;
                 setsockopt(s, SOL_SOCKET, SO_MAX_PACING_RATE, &m, sizeof(m));
         }
+        if (opts->congestion_control)
+                set_congestion_control(s, opts->congestion_control, cb);
         if (opts->tcp_tx_delay)
                 set_tcp_tx_delay(s, opts->tcp_tx_delay, cb);
         set_nonblocking(s, cb);