X-Git-Url: https://git.saurik.com/apple/xnu.git/blobdiff_plain/5ba3f43ea354af8ad55bea84372a2bc834d8757c..HEAD:/bsd/netinet/tcp_ledbat.c diff --git a/bsd/netinet/tcp_ledbat.c b/bsd/netinet/tcp_ledbat.c index fd066b42a..f345934a7 100644 --- a/bsd/netinet/tcp_ledbat.c +++ b/bsd/netinet/tcp_ledbat.c @@ -1,5 +1,5 @@ /* - * Copyright (c) 2010-2014 Apple Inc. All rights reserved. + * Copyright (c) 2010-2020 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * @@ -37,9 +37,7 @@ #include #include -#if INET6 #include -#endif #include #include #include @@ -64,7 +62,7 @@ void tcp_ledbat_pre_fr(struct tcpcb *tp); void tcp_ledbat_post_fr(struct tcpcb *tp, struct tcphdr *th); void tcp_ledbat_after_idle(struct tcpcb *tp); void tcp_ledbat_after_timeout(struct tcpcb *tp); -int tcp_ledbat_delay_ack(struct tcpcb *tp, struct tcphdr *th); +static int tcp_ledbat_delay_ack(struct tcpcb *tp, struct tcphdr *th); void tcp_ledbat_switch_cc(struct tcpcb *tp, uint16_t old_cc_index); struct tcp_cc_algo tcp_cc_ledbat = { @@ -82,61 +80,63 @@ struct tcp_cc_algo tcp_cc_ledbat = { .switch_to = tcp_ledbat_switch_cc }; -/* Target queuing delay in milliseconds. This includes the processing - * and scheduling delay on both of the end-hosts. A LEDBAT sender tries +/* Target queuing delay in milliseconds. This includes the processing + * and scheduling delay on both of the end-hosts. A LEDBAT sender tries * to keep queuing delay below this limit. When the queuing delay - * goes above this limit, a LEDBAT sender will start reducing the + * goes above this limit, a LEDBAT sender will start reducing the * congestion window. * - * The LEDBAT draft says that target queue delay MUST be 100 ms for + * The LEDBAT draft says that target queue delay MUST be 100 ms for * inter-operability. */ SYSCTL_SKMEM_TCP_INT(OID_AUTO, bg_target_qdelay, CTLFLAG_RW | CTLFLAG_LOCKED, - int, target_qdelay, 100, "Target queuing delay"); + int, target_qdelay, 100, "Target queuing delay"); /* Allowed increase and tether are used to place an upper bound on * congestion window based on the amount of data that is outstanding. - * This will limit the congestion window when the amount of data in + * This will limit the congestion window when the amount of data in * flight is little because the application is writing to the socket - * intermittently and is preventing the connection from becoming idle . + * intermittently and is preventing the connection from becoming idle . * * max_allowed_cwnd = allowed_increase + (tether * flight_size) * cwnd = min(cwnd, max_allowed_cwnd) * * 'Allowed_increase' parameter is set to 8. If the flight size is zero, then * we want the congestion window to be at least 8 packets to reduce the - * delay induced by delayed ack. This helps when the receiver is acking + * delay induced by delayed ack. This helps when the receiver is acking * more than 2 packets at a time (stretching acks for better performance). - * + * * 'Tether' is also set to 2. We do not want this to limit the growth of cwnd * during slow-start. - */ + */ SYSCTL_SKMEM_TCP_INT(OID_AUTO, bg_allowed_increase, CTLFLAG_RW | CTLFLAG_LOCKED, - int, allowed_increase, 8, - "Additive constant used to calculate max allowed congestion window"); + int, allowed_increase, 8, + "Additive constant used to calculate max allowed congestion window"); /* Left shift for cwnd to get tether value of 2 */ SYSCTL_SKMEM_TCP_INT(OID_AUTO, bg_tether_shift, CTLFLAG_RW | CTLFLAG_LOCKED, - int, tether_shift, 1, "Tether shift for max allowed congestion window"); + int, tether_shift, 1, "Tether shift for max allowed congestion window"); -/* Start with an initial window of 2. This will help to get more accurate +/* Start with an initial window of 2. This will help to get more accurate * minimum RTT measurement in the beginning. It will help to probe * the path slowly and will not add to the existing delay if the path is * already congested. Using 2 packets will reduce the delay induced by delayed-ack. */ SYSCTL_SKMEM_TCP_INT(OID_AUTO, bg_ss_fltsz, CTLFLAG_RW | CTLFLAG_LOCKED, - uint32_t, bg_ss_fltsz, 2, "Initial congestion window for background transport"); + uint32_t, bg_ss_fltsz, 2, "Initial congestion window for background transport"); extern int rtt_samples_per_slot; -static void update_cwnd(struct tcpcb *tp, uint32_t incr) { +static void +update_cwnd(struct tcpcb *tp, uint32_t incr) +{ uint32_t max_allowed_cwnd = 0, flight_size = 0; uint32_t base_rtt; base_rtt = get_base_rtt(tp); /* If we do not have a good RTT measurement yet, increment - * congestion window by the default value. + * congestion window by the default value. */ if (base_rtt == 0 || tp->t_rttcur == 0) { tp->snd_cwnd += incr; @@ -150,30 +150,32 @@ static void update_cwnd(struct tcpcb *tp, uint32_t incr) { * * Move background slow-start threshold to current * congestion window so that the next time (after some idle - * period), we can attempt to do slow-start till here if there + * period), we can attempt to do slow-start till here if there * is no increase in rtt */ - if (tp->bg_ssthresh < tp->snd_cwnd) + if (tp->bg_ssthresh < tp->snd_cwnd) { tp->bg_ssthresh = tp->snd_cwnd; - tp->snd_cwnd += incr; - + } + tp->snd_cwnd += incr; } else { - /* In response to an increase in rtt, reduce the congestion - * window by one-eighth. This will help to yield immediately + /* In response to an increase in rtt, reduce the congestion + * window by one-eighth. This will help to yield immediately * to a competing stream. */ uint32_t redwin; - redwin = tp->snd_cwnd >> 3; + redwin = tp->snd_cwnd >> 3; tp->snd_cwnd -= redwin; - if (tp->snd_cwnd < bg_ss_fltsz * tp->t_maxseg) + if (tp->snd_cwnd < bg_ss_fltsz * tp->t_maxseg) { tp->snd_cwnd = bg_ss_fltsz * tp->t_maxseg; + } - /* Lower background slow-start threshold so that the connection + /* Lower background slow-start threshold so that the connection * will go into congestion avoidance phase */ - if (tp->bg_ssthresh > tp->snd_cwnd) + if (tp->bg_ssthresh > tp->snd_cwnd) { tp->bg_ssthresh = tp->snd_cwnd; + } } check_max: /* Calculate the outstanding flight size and restrict the @@ -181,40 +183,46 @@ check_max: */ flight_size = tp->snd_max - tp->snd_una; - max_allowed_cwnd = (allowed_increase * tp->t_maxseg) - + (flight_size << tether_shift); + max_allowed_cwnd = (allowed_increase * tp->t_maxseg) + + (flight_size << tether_shift); tp->snd_cwnd = min(tp->snd_cwnd, max_allowed_cwnd); return; } -int tcp_ledbat_init(struct tcpcb *tp) { +int +tcp_ledbat_init(struct tcpcb *tp) +{ #pragma unused(tp) OSIncrementAtomic((volatile SInt32 *)&tcp_cc_ledbat.num_sockets); return 0; } -int tcp_ledbat_cleanup(struct tcpcb *tp) { +int +tcp_ledbat_cleanup(struct tcpcb *tp) +{ #pragma unused(tp) OSDecrementAtomic((volatile SInt32 *)&tcp_cc_ledbat.num_sockets); return 0; } -/* Initialize the congestion window for a connection - * +/* Initialize the congestion window for a connection + * */ void -tcp_ledbat_cwnd_init(struct tcpcb *tp) { +tcp_ledbat_cwnd_init(struct tcpcb *tp) +{ tp->snd_cwnd = tp->t_maxseg * bg_ss_fltsz; tp->bg_ssthresh = tp->snd_ssthresh; } -/* Function to handle an in-sequence ack which is fast-path processing - * of an in sequence ack in tcp_input function (called as header prediction). +/* Function to handle an in-sequence ack which is fast-path processing + * of an in sequence ack in tcp_input function (called as header prediction). * This gets called only during congestion avoidance phase. */ void -tcp_ledbat_congestion_avd(struct tcpcb *tp, struct tcphdr *th) { +tcp_ledbat_congestion_avd(struct tcpcb *tp, struct tcphdr *th) +{ int acked = 0; u_int32_t incr = 0; @@ -232,7 +240,8 @@ tcp_ledbat_congestion_avd(struct tcpcb *tp, struct tcphdr *th) { /* Function to process an ack. */ void -tcp_ledbat_ack_rcvd(struct tcpcb *tp, struct tcphdr *th) { +tcp_ledbat_ack_rcvd(struct tcpcb *tp, struct tcphdr *th) +{ /* * RFC 3465 - Appropriate Byte Counting. * @@ -246,9 +255,9 @@ tcp_ledbat_ack_rcvd(struct tcpcb *tp, struct tcphdr *th) { * greater than or equal to the congestion window. */ - u_int cw = tp->snd_cwnd; - u_int incr = tp->t_maxseg; - int acked = 0; + uint32_t cw = tp->snd_cwnd; + uint32_t incr = tp->t_maxseg; + uint32_t acked = 0; acked = BYTES_ACKED(th, tp); tp->t_bytes_acked += acked; @@ -268,37 +277,46 @@ tcp_ledbat_ack_rcvd(struct tcpcb *tp, struct tcphdr *th) { */ u_int abc_lim; - abc_lim = (tcp_do_rfc3465_lim2 && - tp->snd_nxt == tp->snd_max) ? incr * 2 : incr; + abc_lim = (tp->snd_nxt == tp->snd_max) ? incr * 2 : incr; - incr = lmin(acked, abc_lim); + incr = ulmin(acked, abc_lim); } - if (tp->t_bytes_acked >= cw) + if (tp->t_bytes_acked >= cw) { tp->t_bytes_acked -= cw; - if (incr > 0) + } + if (incr > 0) { update_cwnd(tp, incr); + } } void -tcp_ledbat_pre_fr(struct tcpcb *tp) { +tcp_ledbat_pre_fr(struct tcpcb *tp) +{ uint32_t win; - win = min(tp->snd_wnd, tp->snd_cwnd) / - 2 / tp->t_maxseg; - if ( win < 2 ) + win = min(tp->snd_wnd, tp->snd_cwnd) / + 2 / tp->t_maxseg; + if (win < 2) { win = 2; - tp->snd_ssthresh = win * tp->t_maxseg; - if (tp->bg_ssthresh > tp->snd_ssthresh) + } + tp->snd_ssthresh = win * tp->t_maxseg; + if (tp->bg_ssthresh > tp->snd_ssthresh) { tp->bg_ssthresh = tp->snd_ssthresh; + } tcp_cc_resize_sndbuf(tp); } void -tcp_ledbat_post_fr(struct tcpcb *tp, struct tcphdr *th) { +tcp_ledbat_post_fr(struct tcpcb *tp, struct tcphdr *th) +{ int32_t ss; - ss = tp->snd_max - th->th_ack; + if (th) { + ss = tp->snd_max - th->th_ack; + } else { + ss = tp->snd_max - tp->snd_una; + } /* * Complete ack. Inflate the congestion window to @@ -309,14 +327,15 @@ tcp_ledbat_post_fr(struct tcpcb *tp, struct tcphdr *th) { * would be inclined to send a burst, better to do * it via the slow start mechanism. * - * If the flight size is zero, then make congestion - * window to be worth at least 2 segments to avoid + * If the flight size is zero, then make congestion + * window to be worth at least 2 segments to avoid * delayed acknowledgement (draft-ietf-tcpm-rfc3782-bis-05). */ - if (ss < (int32_t)tp->snd_ssthresh) + if (ss < (int32_t)tp->snd_ssthresh) { tp->snd_cwnd = max(ss, tp->t_maxseg) + tp->t_maxseg; - else + } else { tp->snd_cwnd = tp->snd_ssthresh; + } tp->t_bytes_acked = 0; } @@ -326,13 +345,13 @@ tcp_ledbat_post_fr(struct tcpcb *tp, struct tcphdr *th) { * Clear base history after idle time. */ void -tcp_ledbat_after_idle(struct tcpcb *tp) { - +tcp_ledbat_after_idle(struct tcpcb *tp) +{ /* Reset the congestion window */ tp->snd_cwnd = tp->t_maxseg * bg_ss_fltsz; } -/* Function to change the congestion window when the retransmit +/* Function to change the congestion window when the retransmit * timer fires. The behavior is the same as that for best-effort * TCP, reduce congestion window to one segment and start probing * the link using "slow start". The slow start threshold is set @@ -340,15 +359,18 @@ tcp_ledbat_after_idle(struct tcpcb *tp) { * threshold also. */ void -tcp_ledbat_after_timeout(struct tcpcb *tp) { - if (tp->t_state >= TCPS_ESTABLISHED) { +tcp_ledbat_after_timeout(struct tcpcb *tp) +{ + if (tp->t_state >= TCPS_ESTABLISHED) { u_int win = min(tp->snd_wnd, tp->snd_cwnd) / 2 / tp->t_maxseg; - if (win < 2) + if (win < 2) { win = 2; + } tp->snd_ssthresh = win * tp->t_maxseg; - if (tp->bg_ssthresh > tp->snd_ssthresh) + if (tp->bg_ssthresh > tp->snd_ssthresh) { tp->bg_ssthresh = tp->snd_ssthresh; + } tp->snd_cwnd = tp->t_maxseg; tcp_cc_resize_sndbuf(tp); @@ -359,44 +381,54 @@ tcp_ledbat_after_timeout(struct tcpcb *tp) { * Indicate whether this ack should be delayed. * We can delay the ack if: * - our last ack wasn't a 0-sized window. - * - the peer hasn't sent us a TH_PUSH data packet: if he did, take this - * as a clue that we need to ACK without any delay. This helps higher - * level protocols who won't send us more data even if the window is - * open because their last "segment" hasn't been ACKed + * - the peer hasn't sent us a TH_PUSH data packet: if he did, take this + * as a clue that we need to ACK without any delay. This helps higher + * level protocols who won't send us more data even if the window is + * open because their last "segment" hasn't been ACKed * Otherwise the receiver will ack every other full-sized segment or when the - * delayed ack timer fires. This will help to generate better rtt estimates for + * delayed ack timer fires. This will help to generate better rtt estimates for * the other end if it is a ledbat sender. - * + * */ -int -tcp_ledbat_delay_ack(struct tcpcb *tp, struct tcphdr *th) { - if ((tp->t_flags & TF_RXWIN0SENT) == 0 && - (th->th_flags & TH_PUSH) == 0 && (tp->t_unacksegs == 1)) - return(1); - return(0); +static int +tcp_ledbat_delay_ack(struct tcpcb *tp, struct tcphdr *th) +{ + if (tcp_ack_strategy == TCP_ACK_STRATEGY_MODERN) { + return tcp_cc_delay_ack(tp, th); + } else { + if ((tp->t_flags & TF_RXWIN0SENT) == 0 && + (th->th_flags & TH_PUSH) == 0 && (tp->t_unacksegs == 1)) { + return 1; + } + return 0; + } } /* Change a connection to use ledbat. First, lower bg_ssthresh value - * if it needs to be. + * if it needs to be. */ void -tcp_ledbat_switch_cc(struct tcpcb *tp, uint16_t old_cc_index) { +tcp_ledbat_switch_cc(struct tcpcb *tp, uint16_t old_cc_index) +{ #pragma unused(old_cc_index) uint32_t cwnd; - if (tp->bg_ssthresh == 0 || tp->bg_ssthresh > tp->snd_ssthresh) + if (tp->bg_ssthresh == 0 || tp->bg_ssthresh > tp->snd_ssthresh) { tp->bg_ssthresh = tp->snd_ssthresh; + } cwnd = min(tp->snd_wnd, tp->snd_cwnd); - if (tp->snd_cwnd > tp->bg_ssthresh) + if (tp->snd_cwnd > tp->bg_ssthresh) { cwnd = cwnd / tp->t_maxseg; - else + } else { cwnd = cwnd / 2 / tp->t_maxseg; + } - if (cwnd < bg_ss_fltsz) + if (cwnd < bg_ss_fltsz) { cwnd = bg_ss_fltsz; + } tp->snd_cwnd = cwnd * tp->t_maxseg; tp->t_bytes_acked = 0;