bsd/netinet/tcp_input.c

222 	&rtt_samples_per_slot, 0, "Number of RTT samples stored for rtt history");
362 static void update_base_rtt(struct tcpcb *tp, uint32_t rtt);
910 		 * 1. the bandwidth measured in last rtt, is more
914 		 * one forth of the bandwidth measured in last rtt, this
992  * 1. if the rtt seen on the connection is climbing up, we do not
2288 				 * Recalculate the transmit timer / rtt.
3417 		 * Since we now have an rtt measurement, cancel the
4167 update_base_rtt(struct tcpcb *tp, uint32_t rtt)
4174 		tp->rtt_hist[0] = rtt;
4177 		tp->rtt_hist[0] = min(tp->rtt_hist[0], rtt);
4186 tcp_xmit_timer(tp, rtt)
4188 	int rtt;
4195 	if (rtt > 0) {
4196 		tp->t_rttcur = rtt;
4197 		update_base_rtt(tp, rtt);
4205 		 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
4208 		 * Freebsd adjusts rtt to origin 0 by subtracting 1 from the provided
4209 		 * rtt value. This was required because of the way t_rtttime was
4213 		delta = (rtt << TCP_DELTA_SHIFT)
4220 		 * We accumulate a smoothed rtt variance (actually, a
4222 		 * timer to smoothed rtt + 4 times the smoothed variance.
4239 		 * No rtt measurement yet - use the unsmoothed rtt.
4240 		 * Set the variance to half the rtt (so our first
4241 		 * retransmit happens at 3*rtt).
4243 		tp->t_srtt = rtt << TCP_RTT_SHIFT;
4244 		tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
4252 	 * the retransmit should happen at rtt + 4 * rttvar.
4263 		max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX,
4348 	register int rtt, mss;
4449 	 * While we're here, check if there's an initial rtt
4453 	if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt) != 0) {
4900 	 * retransmit timer or rtt calculation.