static void dctcp_init(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); if ((tp->ecn_flags & TCP_ECN_OK) || (sk->sk_state == TCP_LISTEN || sk->sk_state == TCP_CLOSE)) { struct dctcp *ca = inet_csk_ca(sk); ca->prior_snd_una = tp->snd_una; ca->prior_rcv_nxt = tp->rcv_nxt; ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA); ca->loss_cwnd = 0; ca->ce_state = 0; dctcp_reset(tp, ca); return; } /* No ECN support? Fall back to Reno. Also need to clear * ECT from sk since it is set during 3WHS for DCTCP. */ inet_csk(sk)->icsk_ca_ops = &dctcp_reno; INET_ECN_dontxmit(sk); }
static void dctcp_update_alpha(struct sock *sk, u32 flags) { const struct tcp_sock *tp = tcp_sk(sk); struct dctcp *ca = inet_csk_ca(sk); u32 acked_bytes = tp->snd_una - ca->prior_snd_una; /* If ack did not advance snd_una, count dupack as MSS size. * If ack did update window, do not count it at all. */ if (acked_bytes == 0 && !(flags & CA_ACK_WIN_UPDATE)) acked_bytes = inet_csk(sk)->icsk_ack.rcv_mss; if (acked_bytes) { ca->acked_bytes_total += acked_bytes; ca->prior_snd_una = tp->snd_una; if (flags & CA_ACK_ECE) ca->acked_bytes_ecn += acked_bytes; } /* Expired RTT */ if (!before(tp->snd_una, ca->next_seq)) { u64 bytes_ecn = ca->acked_bytes_ecn; u32 alpha = ca->dctcp_alpha; /* alpha = (1 - g) * alpha + g * F */ alpha -= min_not_zero(alpha, alpha >> dctcp_shift_g); if (bytes_ecn) { /* If dctcp_shift_g == 1, a 32bit value would overflow * after 8 Mbytes. */ bytes_ecn <<= (10 - dctcp_shift_g); do_div(bytes_ecn, max(1U, ca->acked_bytes_total)); alpha = min(alpha + (u32)bytes_ecn, DCTCP_MAX_ALPHA); } /* dctcp_alpha can be read from dctcp_get_info() without * synchro, so we ask compiler to not use dctcp_alpha * as a temporary variable in prior operations. */ WRITE_ONCE(ca->dctcp_alpha, alpha); dctcp_reset(tp, ca); }
static void dctcp_update_alpha(struct sock *sk, u32 flags) { const struct tcp_sock *tp = tcp_sk(sk); struct dctcp *ca = inet_csk_ca(sk); u32 acked_bytes = tp->snd_una - ca->prior_snd_una; /* If ack did not advance snd_una, count dupack as MSS size. * If ack did update window, do not count it at all. */ if (acked_bytes == 0 && !(flags & CA_ACK_WIN_UPDATE)) acked_bytes = inet_csk(sk)->icsk_ack.rcv_mss; if (acked_bytes) { ca->acked_bytes_total += acked_bytes; ca->prior_snd_una = tp->snd_una; if (flags & CA_ACK_ECE) ca->acked_bytes_ecn += acked_bytes; } /* Expired RTT */ if (!before(tp->snd_una, ca->next_seq)) { /* For avoiding denominator == 1. */ if (ca->acked_bytes_total == 0) ca->acked_bytes_total = 1; /* alpha = (1 - g) * alpha + g * F */ ca->dctcp_alpha = ca->dctcp_alpha - (ca->dctcp_alpha >> dctcp_shift_g) + (ca->acked_bytes_ecn << (10U - dctcp_shift_g)) / ca->acked_bytes_total; if (ca->dctcp_alpha > DCTCP_MAX_ALPHA) /* Clamp dctcp_alpha to max. */ ca->dctcp_alpha = DCTCP_MAX_ALPHA; dctcp_reset(tp, ca); } }