/*
* Initialize the congestion window at the beginning of a connection or
* after idle time
*/
static void tcp_cubic_cwnd_init_or_reset(struct tcpcb *tp)
{
VERIFY(tp->t_ccstate != NULL);
tcp_cubic_clear_state(tp);
tcp_cc_cwnd_init_or_reset(tp);
tp->t_pipeack = 0;
tcp_clear_pipeack_state(tp);
/* Start counting bytes for RFC 3465 again */
tp->t_bytes_acked = 0;
/*
* slow start threshold could get initialized to a lower value
* when there is a cached value in the route metrics. In this case,
* the connection can enter congestion avoidance without any packet
* loss and Cubic will enter steady-state too early. It is better
* to always probe to find the initial slow-start threshold.
*/
if (tp->t_inpcb->inp_stat->txbytes <= TCP_CC_CWND_INIT_BYTES
&& tp->snd_ssthresh < (TCP_MAXWIN << TCP_MAX_WINSHIFT))
tp->snd_ssthresh = TCP_MAXWIN << TCP_MAX_WINSHIFT;
/* Initialize cubic last max to be same as ssthresh */
tp->t_ccstate->cub_last_max = tp->snd_ssthresh;
}
static int tcp_cubic_init(struct tcpcb *tp)
{
OSIncrementAtomic((volatile SInt32 *)&tcp_cc_cubic.num_sockets);
VERIFY(tp->t_ccstate != NULL);
tcp_cubic_clear_state(tp);
return (0);
}
static void
tcp_cubic_after_timeout(struct tcpcb *tp)
{
VERIFY(tp->t_ccstate != NULL);
if (!IN_FASTRECOVERY(tp)) {
tcp_cubic_clear_state(tp);
tcp_cubic_pre_fr(tp);
}
/*
* Close the congestion window down to one segment as a retransmit
* timeout might indicate severe congestion.
*/
tp->snd_cwnd = tp->t_maxseg;
}
