bsd/netinet/tcp_input.c

228 	&rtt_samples_per_slot, 0, "Number of RTT samples stored for rtt history");
391 static void update_base_rtt(struct tcpcb *tp, uint32_t rtt);
1064 		 * 1. the bandwidth measured in last rtt, is more
1068 		 * one forth of the bandwidth measured in last rtt, this
1146  * 1. if the rtt seen on the connection is climbing up, we do not
4465 update_base_rtt(struct tcpcb *tp, uint32_t rtt)
4488 		tp->rtt_hist[0] = rtt;
4491 		tp->rtt_hist[0] = min(tp->rtt_hist[0], rtt);
4527 tcp_xmit_timer(register struct tcpcb *tp, int rtt,
4544 			tp->t_srtt = max(tp->t_srtt_prev, rtt);
4546 			tp->t_rttvar = max(tp->t_rttvar_prev, (rtt >> 1));
4561 	if (rtt > 0) {
4562 		tp->t_rttcur = rtt;
4563 		update_base_rtt(tp, rtt);
4571 		 * an alpha of .875 (srtt = rtt/8 + srtt*7/8 in fixed
4574 		 * Freebsd adjusts rtt to origin 0 by subtracting 1
4575 		 * from the provided rtt value. This was required because
4580 		delta = (rtt << TCP_DELTA_SHIFT)
4587 		 * We accumulate a smoothed rtt variance (actually, a
4589 		 * timer to smoothed rtt + 4 times the smoothed variance.
4606 		 * No rtt measurement yet - use the unsmoothed rtt.
4607 		 * Set the variance to half the rtt (so our first
4608 		 * retransmit happens at 3*rtt).
4610 		tp->t_srtt = rtt << TCP_RTT_SHIFT;
4611 		tp->t_rttvar = rtt << (TCP_RTTVAR_SHIFT - 1);
4622 	 * the retransmit should happen at rtt + 4 * rttvar.
4633 		max(tp->t_rttmin, rtt + 2), TCPTV_REXMTMAX,
4718 	register int rtt, mss;
4806 	 * While we're here, check if there's an initial rtt
4810 	if (tp->t_srtt == 0 && (rtt = rt->rt_rmx.rmx_rtt) != 0) {
5316 	 * retransmit timer or rtt calculation.