From dda0febbd7fdffb3b24dc6cc76929f3d523a6fc6 Mon Sep 17 00:00:00 2001 From: Yuk1n0 <39364985+Yuk1n0@users.noreply.github.com> Date: Tue, 19 Nov 2019 22:37:20 +0800 Subject: [PATCH] Adjust directory structure --- tcp_bbrplus.c | 1168 ------------------------------------------------- 1 file changed, 1168 deletions(-) delete mode 100644 tcp_bbrplus.c diff --git a/tcp_bbrplus.c b/tcp_bbrplus.c deleted file mode 100644 index 2495a33..0000000 --- a/tcp_bbrplus.c +++ /dev/null @@ -1,1168 +0,0 @@ -/* Bottleneck Bandwidth and RTT (BBR) congestion control - * - * BBR congestion control computes the sending rate based on the delivery - * rate (throughput) estimated from ACKs. In a nutshell: - * - * On each ACK, update our model of the network path: - * bottleneck_bandwidth = windowed_max(delivered / elapsed, 10 round trips) - * min_rtt = windowed_min(rtt, 10 seconds) - * pacing_rate = pacing_gain * bottleneck_bandwidth - * cwnd = max(cwnd_gain * bottleneck_bandwidth * min_rtt, 4) - * - * The core algorithm does not react directly to packet losses or delays, - * although BBR may adjust the size of next send per ACK when loss is - * observed, or adjust the sending rate if it estimates there is a - * traffic policer, in order to keep the drop rate reasonable. - * - * Here is a state transition diagram for BBR: - * - * | - * V - * +---> STARTUP ----+ - * | | | - * | V | - * | DRAIN ----+ - * | | | - * | V | - * +---> PROBE_BW ----+ - * | ^ | | - * | | | | - * | +----+ | - * | | - * +---- PROBE_RTT <--+ - * - * A BBR flow starts in STARTUP, and ramps up its sending rate quickly. - * When it estimates the pipe is full, it enters DRAIN to drain the queue. - * In steady state a BBR flow only uses PROBE_BW and PROBE_RTT. - * A long-lived BBR flow spends the vast majority of its time remaining - * (repeatedly) in PROBE_BW, fully probing and utilizing the pipe's bandwidth - * in a fair manner, with a small, bounded queue. *If* a flow has been - * continuously sending for the entire min_rtt window, and hasn't seen an RTT - * sample that matches or decreases its min_rtt estimate for 10 seconds, then - * it briefly enters PROBE_RTT to cut inflight to a minimum value to re-probe - * the path's two-way propagation delay (min_rtt). When exiting PROBE_RTT, if - * we estimated that we reached the full bw of the pipe then we enter PROBE_BW; - * otherwise we enter STARTUP to try to fill the pipe. - * - * BBR is described in detail in: - * "BBR: Congestion-Based Congestion Control", - * Neal Cardwell, Yuchung Cheng, C. Stephen Gunn, Soheil Hassas Yeganeh, - * Van Jacobson. ACM Queue, Vol. 14 No. 5, September-October 2016. - * - * There is a public e-mail list for discussing BBR development and testing: - * https://groups.google.com/forum/#!forum/bbr-dev - * - * NOTE: BBR might be used with the fq qdisc ("man tc-fq") with pacing enabled, - * otherwise TCP stack falls back to an internal pacing using one high - * resolution timer per TCP socket and may use more resources. - */ -#include -#include -#include -#include -#include -#include - -/* Scale factor for rate in pkt/uSec unit to avoid truncation in bandwidth - * estimation. The rate unit ~= (1500 bytes / 1 usec / 2^24) ~= 715 bps. - * This handles bandwidths from 0.06pps (715bps) to 256Mpps (3Tbps) in a u32. - * Since the minimum window is >=4 packets, the lower bound isn't - * an issue. The upper bound isn't an issue with existing technologies. - */ -#define BW_SCALE 24 -#define BW_UNIT (1 << BW_SCALE) - -#define BBR_SCALE 8 /* scaling factor for fractions in BBR (e.g. gains) */ -#define BBR_UNIT (1 << BBR_SCALE) - -/* BBR has the following modes for deciding how fast to send: */ -enum bbr_mode { - BBR_STARTUP, /* ramp up sending rate rapidly to fill pipe */ - BBR_DRAIN, /* drain any queue created during startup */ - BBR_PROBE_BW, /* discover, share bw: pace around estimated bw */ - BBR_PROBE_RTT, /* cut inflight to min to probe min_rtt */ -}; - -/* BBR congestion control block */ -struct bbr { - u32 min_rtt_us; /* min RTT in min_rtt_win_sec window */ - u32 min_rtt_stamp; /* timestamp of min_rtt_us */ - u32 probe_rtt_done_stamp; /* end time for BBR_PROBE_RTT mode */ - struct minmax bw; /* Max recent delivery rate in pkts/uS << 24 */ - u32 rtt_cnt; /* count of packet-timed rounds elapsed */ - u32 next_rtt_delivered; /* scb->tx.delivered at end of round */ - u64 cycle_mstamp; /* time of this cycle phase start */ - u32 mode:3, /* current bbr_mode in state machine */ - prev_ca_state:3, /* CA state on previous ACK */ - packet_conservation:1, /* use packet conservation? */ - restore_cwnd:1, /* decided to revert cwnd to old value */ - round_start:1, /* start of packet-timed tx->ack round? */ - cycle_len:4, /* phases in this PROBE_BW gain cycle */ - tso_segs_goal:7, /* segments we want in each skb we send */ - idle_restart:1, /* restarting after idle? */ - probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */ - unused:8, - lt_is_sampling:1, /* taking long-term ("LT") samples now? */ - lt_rtt_cnt:7, /* round trips in long-term interval */ - lt_use_bw:1; /* use lt_bw as our bw estimate? */ - u32 lt_bw; /* LT est delivery rate in pkts/uS << 24 */ - u32 lt_last_delivered; /* LT intvl start: tp->delivered */ - u32 lt_last_stamp; /* LT intvl start: tp->delivered_mstamp */ - u32 lt_last_lost; /* LT intvl start: tp->lost */ - u32 pacing_gain:10, /* current gain for setting pacing rate */ - cwnd_gain:10, /* current gain for setting cwnd */ - full_bw_cnt:3, /* number of rounds without large bw gains */ - cycle_idx:3, /* current index in pacing_gain cycle array */ - has_seen_rtt:1, /* have we seen an RTT sample yet? */ - unused_b:5; - u32 prior_cwnd; /* prior cwnd upon entering loss recovery */ - u32 full_bw; /* recent bw, to estimate if pipe is full */ - /* For tracking ACK aggregation: */ - u64 ack_epoch_mstamp; - /* start of ACK sampling epoch */ - u16 extra_acked[2]; - /* max excess data ACKed in epoch */ - u32 ack_epoch_acked:20, /* packets (S)ACKed in sampling epoch */ - extra_acked_win_rtts:5, /* age of extra_acked, in round trips */ - extra_acked_win_idx:1, /* current index in extra_acked array */ - unused1:6; -}; - -#define CYCLE_LEN 8 /* number of phases in a pacing gain cycle */ - -/* Window length of bw filter (in rounds): */ -static const int bbr_bw_rtts = CYCLE_LEN + 2; -/* Window length of min_rtt filter (in sec): */ -static const u32 bbr_min_rtt_win_sec = 10; -/* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode: */ -static const u32 bbr_probe_rtt_mode_ms = 200; -/* Skip TSO below the following bandwidth (bits/sec): */ -static const int bbr_min_tso_rate = 1200000; - -/* We use a high_gain value of 2/ln(2) because it's the smallest pacing gain - * that will allow a smoothly increasing pacing rate that will double each RTT - * and send the same number of packets per RTT that an un-paced, slow-starting - * Reno or CUBIC flow would: - */ -static const int bbr_high_gain = BBR_UNIT * 2885 / 1000 + 1; -/* The pacing gain of 1/high_gain in BBR_DRAIN is calculated to typically drain - * the queue created in BBR_STARTUP in a single round: - */ -static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885; -/* The gain for deriving steady-state cwnd tolerates delayed/stretched ACKs: */ -static const int bbr_cwnd_gain = BBR_UNIT * 2; - -enum bbr_pacing_gain_phase { - BBR_BW_PROBE_UP = 0, - BBR_BW_PROBE_DOWN = 1, - BBR_BW_PROBE_CRUISE = 2, -}; - -/* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw: */ -static const int bbr_pacing_gain[] = { - BBR_UNIT * 5 / 4, /* probe for more available bw */ - BBR_UNIT * 3 / 4, /* drain queue and/or yield bw to other flows */ - BBR_UNIT, BBR_UNIT, BBR_UNIT, /* cruise at 1.0*bw to utilize pipe, */ - BBR_UNIT, BBR_UNIT, BBR_UNIT /* without creating excess queue... */ -}; -/* Randomize the starting gain cycling phase over N phases: */ -static const u32 bbr_cycle_rand = 7; - -/* Try to keep at least this many packets in flight, if things go smoothly. For - * smooth functioning, a sliding window protocol ACKing every other packet - * needs at least 4 packets in flight: - */ -static const u32 bbr_cwnd_min_target = 4; - -/* To estimate if BBR_STARTUP mode (i.e. high_gain) has filled pipe... */ -/* If bw has increased significantly (1.25x), there may be more bw available: */ -static const u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4; -/* But after 3 rounds w/o significant bw growth, estimate pipe is full: */ -static const u32 bbr_full_bw_cnt = 3; - -/* "long-term" ("LT") bandwidth estimator parameters... */ -/* The minimum number of rounds in an LT bw sampling interval: */ -static const u32 bbr_lt_intvl_min_rtts = 4; -/* If lost/delivered ratio > 20%, interval is "lossy" and we may be policed: */ -static const u32 bbr_lt_loss_thresh = 50; -/* If 2 intervals have a bw ratio <= 1/8, their bw is "consistent": */ -static const u32 bbr_lt_bw_ratio = BBR_UNIT / 8; -/* If 2 intervals have a bw diff <= 4 Kbit/sec their bw is "consistent": */ -static const u32 bbr_lt_bw_diff = 4000 / 8; -/* If we estimate we're policed, use lt_bw for this many round trips: */ -static const u32 bbr_lt_bw_max_rtts = 48; - -/* Gain factor for adding extra_acked to target cwnd: */ -static const int bbr_extra_acked_gain = BBR_UNIT; -/* Window length of extra_acked window. Max allowed val is 31. */ -static const u32 bbr_extra_acked_win_rtts = 10; -/* Max allowed val for ack_epoch_acked, after which sampling epoch is reset */ -static const u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20; -/* Time period for clamping cwnd increment due to ack aggregation */ -static const u32 bbr_extra_acked_max_us = 100 * 1000; - -/* Each cycle, try to hold sub-unity gain until inflight <= BDP. */ -static const bool bbr_drain_to_target = true; /* default: enabled */ - -extern bool tcp_snd_wnd_test(const struct tcp_sock *tp, - const struct sk_buff *skb, - unsigned int cur_mss); - -/* Do we estimate that STARTUP filled the pipe? */ -static bool bbr_full_bw_reached(const struct sock *sk) -{ - const struct bbr *bbr = inet_csk_ca(sk); - - return bbr->full_bw_cnt >= bbr_full_bw_cnt; -} - -static void bbr_set_cycle_idx(struct sock *sk, int cycle_idx) -{ - struct bbr *bbr = inet_csk_ca(sk); - bbr->cycle_idx = cycle_idx; - bbr->pacing_gain = bbr->lt_use_bw ? - BBR_UNIT : bbr_pacing_gain[bbr->cycle_idx]; -} - -u32 bbr_max_bw(const struct sock *sk); -u32 bbr_inflight(struct sock *sk, u32 bw, int gain); -u32 bbr_max_bw(const struct sock *sk); - -static void bbr_drain_to_target_cycling(struct sock *sk, - const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 elapsed_us = - tcp_stamp_us_delta(tp->delivered_mstamp, bbr->cycle_mstamp); - u32 inflight, bw; - if (bbr->mode != BBR_PROBE_BW) - return; - - /* Always need to probe for bw before we forget good bw estimate. */ - if (elapsed_us > bbr->cycle_len * bbr->min_rtt_us) { - /* Start a new PROBE_BW probing cycle of [2 to 8] x min_rtt. */ - bbr->cycle_mstamp = tp->delivered_mstamp; - bbr->cycle_len = CYCLE_LEN - prandom_u32_max(bbr_cycle_rand); - bbr_set_cycle_idx(sk, BBR_BW_PROBE_UP); /* probe bandwidth */ - return; - } - /* The pacing_gain of 1.0 paces at the estimated bw to try to fully - * use the pipe without increasing the queue. - */ - if (bbr->pacing_gain == BBR_UNIT) - return; - inflight = rs->prior_in_flight; /* what was in-flight before ACK? */ - bw = bbr_max_bw(sk); - /* A pacing_gain < 1.0 tries to drain extra queue we added if bw - * probing didn't find more bw. If inflight falls to match BDP then we - * estimate queue is drained; persisting would underutilize the pipe. - */ - if (bbr->pacing_gain < BBR_UNIT) { - if (inflight <= bbr_inflight(sk, bw, BBR_UNIT)) - bbr_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE); /* cruise */ - return; - } - /* A pacing_gain > 1.0 probes for bw by trying to raise inflight to at - * least pacing_gain*BDP; this may take more than min_rtt if min_rtt is - * small (e.g. on a LAN). We do not persist if packets are lost, since - * a path with small buffers may not hold that much. Similarly we exit - * if we were prevented by app/recv-win from reaching the target. - */ - if (elapsed_us > bbr->min_rtt_us && - (inflight >= bbr_inflight(sk, bw, bbr->pacing_gain) || - rs->losses || /* perhaps pacing_gain*BDP won't fit */ - rs->is_app_limited || /* previously app-limited */ - !tcp_send_head(sk) || /* currently app/rwin-limited */ - !tcp_snd_wnd_test(tp, tcp_send_head(sk), tp->mss_cache))) { - bbr_set_cycle_idx(sk, BBR_BW_PROBE_DOWN); /* drain queue */ - return; - } -} - -/* Return maximum extra acked in past k-2k round trips, - * where k = bbr_extra_acked_win_rtts. - */ -static u16 bbr_extra_acked(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - return max(bbr->extra_acked[0], bbr->extra_acked[1]); -} - -/* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */ -u32 bbr_max_bw(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return minmax_get(&bbr->bw); -} - -/* Return the estimated bandwidth of the path, in pkts/uS << BW_SCALE. */ -static u32 bbr_bw(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return bbr->lt_use_bw ? bbr->lt_bw : bbr_max_bw(sk); -} - -/* Return rate in bytes per second, optionally with a gain. - * The order here is chosen carefully to avoid overflow of u64. This should - * work for input rates of up to 2.9Tbit/sec and gain of 2.89x. - */ -static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain) -{ - rate *= tcp_mss_to_mtu(sk, tcp_sk(sk)->mss_cache); - rate *= gain; - rate >>= BBR_SCALE; - rate *= USEC_PER_SEC; - return rate >> BW_SCALE; -} - -/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */ -static u32 bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain) -{ - u64 rate = bw; - - rate = bbr_rate_bytes_per_sec(sk, rate, gain); - rate = min_t(u64, rate, sk->sk_max_pacing_rate); - return rate; -} - -/* Initialize pacing rate to: high_gain * init_cwnd / RTT. */ -static void bbr_init_pacing_rate_from_rtt(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u64 bw; - u32 rtt_us; - - if (tp->srtt_us) { /* any RTT sample yet? */ - rtt_us = max(tp->srtt_us >> 3, 1U); - bbr->has_seen_rtt = 1; - } else { /* no RTT sample yet */ - rtt_us = USEC_PER_MSEC; /* use nominal default RTT */ - } - bw = (u64)tp->snd_cwnd * BW_UNIT; - do_div(bw, rtt_us); - sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain); -} - -/* Pace using current bw estimate and a gain factor. In order to help drive the - * network toward lower queues while maintaining high utilization and low - * latency, the average pacing rate aims to be slightly (~1%) lower than the - * estimated bandwidth. This is an important aspect of the design. In this - * implementation this slightly lower pacing rate is achieved implicitly by not - * including link-layer headers in the packet size used for the pacing rate. - */ -static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 rate = bbr_bw_to_pacing_rate(sk, bw, gain); - - if (unlikely(!bbr->has_seen_rtt && tp->srtt_us)) - bbr_init_pacing_rate_from_rtt(sk); - if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate) - sk->sk_pacing_rate = rate; -} - -/* Return count of segments we want in the skbs we send, or 0 for default. */ -static u32 bbr_tso_segs_goal(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return bbr->tso_segs_goal; -} - -static void bbr_set_tso_segs_goal(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 min_segs; - - min_segs = sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2; - bbr->tso_segs_goal = min(tcp_tso_autosize(sk, tp->mss_cache, min_segs), - 0x7FU); -} - -/* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */ -static void bbr_save_cwnd(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr->prev_ca_state < TCP_CA_Recovery && bbr->mode != BBR_PROBE_RTT) - bbr->prior_cwnd = tp->snd_cwnd; /* this cwnd is good enough */ - else /* loss recovery or BBR_PROBE_RTT have temporarily cut cwnd */ - bbr->prior_cwnd = max(bbr->prior_cwnd, tp->snd_cwnd); -} - -static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - if (event == CA_EVENT_TX_START && tp->app_limited) { - bbr->idle_restart = 1; - bbr->ack_epoch_mstamp = tp->tcp_mstamp; - bbr->ack_epoch_acked = 0; - - /* Avoid pointless buffer overflows: pace at est. bw if we don't - * need more speed (we're restarting from idle and app-limited). - */ - if (bbr->mode == BBR_PROBE_BW) - bbr_set_pacing_rate(sk, bbr_bw(sk), BBR_UNIT); - } -} - -/* Find target cwnd. Right-size the cwnd based on min RTT and the - * estimated bottleneck bandwidth: - * - * cwnd = bw * min_rtt * gain = BDP * gain - * - * The key factor, gain, controls the amount of queue. While a small gain - * builds a smaller queue, it becomes more vulnerable to noise in RTT - * measurements (e.g., delayed ACKs or other ACK compression effects). This - * noise may cause BBR to under-estimate the rate. - * - * To achieve full performance in high-speed paths, we budget enough cwnd to - * fit full-sized skbs in-flight on both end hosts to fully utilize the path: - * - one skb in sending host Qdisc, - * - one skb in sending host TSO/GSO engine - * - one skb being received by receiver host LRO/GRO/delayed-ACK engine - * Don't worry, at low rates (bbr_min_tso_rate) this won't bloat cwnd because - * in such cases tso_segs_goal is 1. The minimum cwnd is 4 packets, - * which allows 2 outstanding 2-packet sequences, to try to keep pipe - * full even with ACK-every-other-packet delayed ACKs. - */ -static u32 bbr_bdp(struct sock *sk, u32 bw, int gain) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 bdp; - u64 w; - - /* If we've never had a valid RTT sample, cap cwnd at the initial - * default. This should only happen when the connection is not using TCP - * timestamps and has retransmitted all of the SYN/SYNACK/data packets - * ACKed so far. In this case, an RTO can cut cwnd to 1, in which - * case we need to slow-start up toward something safe: TCP_INIT_CWND. - */ - if (unlikely(bbr->min_rtt_us == ~0U)) /* no valid RTT samples yet? */ - return TCP_INIT_CWND; /* be safe: cap at default initial cwnd*/ - - w = (u64)bw * bbr->min_rtt_us; - - /* Apply a gain to the given value, then remove the BW_SCALE shift. */ - bdp = (((w * gain) >> BBR_SCALE) + BW_UNIT - 1) / BW_UNIT; - - return bdp; -} - -static u32 bbr_quantization_budget(struct sock *sk, u32 cwnd, int gain) -{ - - /* Allow enough full-sized skbs in flight to utilize end systems. */ - cwnd += 3 * bbr_tso_segs_goal(sk); - - return cwnd; -} - -/* Find inflight based on min RTT and the estimated bottleneck bandwidth. */ -u32 bbr_inflight(struct sock *sk, u32 bw, int gain) -{ - u32 inflight; - inflight = bbr_bdp(sk, bw, gain); - inflight = bbr_quantization_budget(sk, inflight, gain); - return inflight; - -} - -/* Find the cwnd increment based on estimate of ack aggregation */ -static u32 bbr_ack_aggregation_cwnd(struct sock *sk) -{ - u32 max_aggr_cwnd, aggr_cwnd = 0; - if (bbr_extra_acked_gain && bbr_full_bw_reached(sk)) { - max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us) - / BW_UNIT; - aggr_cwnd = (bbr_extra_acked_gain * bbr_extra_acked(sk)) - >> BBR_SCALE; - aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd); - } - return aggr_cwnd; -} - -/* An optimization in BBR to reduce losses: On the first round of recovery, we - * follow the packet conservation principle: send P packets per P packets acked. - * After that, we slow-start and send at most 2*P packets per P packets acked. - * After recovery finishes, or upon undo, we restore the cwnd we had when - * recovery started (capped by the target cwnd based on estimated BDP). - * - * TODO(ycheng/ncardwell): implement a rate-based approach. - */ - -static bool bbr_set_cwnd_to_recover_or_restore( - struct sock *sk, const struct rate_sample *rs, u32 acked, u32 *new_cwnd) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u8 prev_state = bbr->prev_ca_state, state = inet_csk(sk)->icsk_ca_state; - u32 cwnd = tp->snd_cwnd; - - /* An ACK for P pkts should release at most 2*P packets. We do this - * in two steps. First, here we deduct the number of lost packets. - * Then, in bbr_set_cwnd() we slow start up toward the target cwnd. - */ - if (rs->losses > 0) - cwnd = max_t(s32, cwnd - rs->losses, 1); - - if (state == TCP_CA_Recovery && prev_state != TCP_CA_Recovery) { - /* Starting 1st round of Recovery, so do packet conservation. */ - bbr->packet_conservation = 1; - bbr->next_rtt_delivered = tp->delivered; /* start round now */ - /* Cut unused cwnd from app behavior, TSQ, or TSO deferral: */ - cwnd = tcp_packets_in_flight(tp) + acked; - } else if (prev_state >= TCP_CA_Recovery && state < TCP_CA_Recovery) { - /* Exiting loss recovery; restore cwnd saved before recovery. */ - bbr->restore_cwnd = 1; - bbr->packet_conservation = 0; - } - bbr->prev_ca_state = state; - - if (bbr->restore_cwnd) { - /* Restore cwnd after exiting loss recovery or PROBE_RTT. */ - cwnd = max(cwnd, bbr->prior_cwnd); - bbr->restore_cwnd = 0; - } - - if (bbr->packet_conservation) { - *new_cwnd = max(cwnd, tcp_packets_in_flight(tp) + acked); - return true; /* yes, using packet conservation */ - } - *new_cwnd = cwnd; - return false; -} - -/* Slow-start up toward target cwnd (if bw estimate is growing, or packet loss - * has drawn us down below target), or snap down to target if we're above it. - */ -static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs, - u32 acked, u32 bw, int gain) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 cwnd = 0, target_cwnd = 0; - - if (!acked) - return; - - if (bbr_set_cwnd_to_recover_or_restore(sk, rs, acked, &cwnd)) - goto done; - - /* If we're below target cwnd, slow start cwnd toward target cwnd. */ - target_cwnd = bbr_bdp(sk, bw, gain); - //// - /* Increment the cwnd to account for excess ACKed data that seems - * due to aggregation (of data and/or ACKs) visible in the ACK stream. - */ - target_cwnd += bbr_ack_aggregation_cwnd(sk); - //// - target_cwnd = bbr_quantization_budget(sk, target_cwnd, gain); - if (bbr_full_bw_reached(sk)) /* only cut cwnd if we filled the pipe */ - cwnd = min(cwnd + acked, target_cwnd); - else if (cwnd < target_cwnd || tp->delivered < TCP_INIT_CWND) - cwnd = cwnd + acked; - cwnd = max(cwnd, bbr_cwnd_min_target); - -done: - tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp); /* apply global cap */ - if (bbr->mode == BBR_PROBE_RTT) /* drain queue, refresh min_rtt */ - tp->snd_cwnd = min(tp->snd_cwnd, bbr_cwnd_min_target); -} - -/* End cycle phase if it's time and/or we hit the phase's in-flight target. */ -static bool bbr_is_next_cycle_phase(struct sock *sk, - const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - bool is_full_length = - tcp_stamp_us_delta(tp->delivered_mstamp, bbr->cycle_mstamp) > - bbr->min_rtt_us; - u32 inflight, bw; - - /* The pacing_gain of 1.0 paces at the estimated bw to try to fully - * use the pipe without increasing the queue. - */ - if (bbr->pacing_gain == BBR_UNIT) - return is_full_length; /* just use wall clock time */ - - inflight = rs->prior_in_flight; /* what was in-flight before ACK? */ - bw = bbr_max_bw(sk); - - /* A pacing_gain > 1.0 probes for bw by trying to raise inflight to at - * least pacing_gain*BDP; this may take more than min_rtt if min_rtt is - * small (e.g. on a LAN). We do not persist if packets are lost, since - * a path with small buffers may not hold that much. - */ - if (bbr->pacing_gain > BBR_UNIT) - return is_full_length && - (rs->losses || /* perhaps pacing_gain*BDP won't fit */ - inflight >= bbr_inflight(sk, bw, bbr->pacing_gain)); - - /* A pacing_gain < 1.0 tries to drain extra queue we added if bw - * probing didn't find more bw. If inflight falls to match BDP then we - * estimate queue is drained; persisting would underutilize the pipe. - */ - return is_full_length || - inflight <= bbr_inflight(sk, bw, BBR_UNIT); -} - -static void bbr_advance_cycle_phase(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - - bbr->cycle_idx = (bbr->cycle_idx + 1) & (CYCLE_LEN - 1); - bbr->cycle_mstamp = tp->delivered_mstamp; - bbr->pacing_gain = bbr_pacing_gain[bbr->cycle_idx]; -} - -/* Gain cycling: cycle pacing gain to converge to fair share of available bw. */ -static void bbr_update_cycle_phase(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr_drain_to_target) { - bbr_drain_to_target_cycling(sk, rs); - return; - } - - if ((bbr->mode == BBR_PROBE_BW) && !bbr->lt_use_bw && - bbr_is_next_cycle_phase(sk, rs)) - bbr_advance_cycle_phase(sk); -} - -static void bbr_reset_startup_mode(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->mode = BBR_STARTUP; - bbr->pacing_gain = bbr_high_gain; - bbr->cwnd_gain = bbr_high_gain; -} - -static void bbr_reset_probe_bw_mode(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->mode = BBR_PROBE_BW; - bbr->pacing_gain = BBR_UNIT; - bbr->cwnd_gain = bbr_cwnd_gain; - bbr->cycle_idx = CYCLE_LEN - 1 - prandom_u32_max(bbr_cycle_rand); - bbr_advance_cycle_phase(sk); /* flip to next phase of gain cycle */ -} - -static void bbr_reset_mode(struct sock *sk) -{ - if (!bbr_full_bw_reached(sk)) - bbr_reset_startup_mode(sk); - else - bbr_reset_probe_bw_mode(sk); -} - -/* Start a new long-term sampling interval. */ -static void bbr_reset_lt_bw_sampling_interval(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr->lt_last_stamp = div_u64(tp->delivered_mstamp, USEC_PER_MSEC); - bbr->lt_last_delivered = tp->delivered; - bbr->lt_last_lost = tp->lost; - bbr->lt_rtt_cnt = 0; -} - -/* Completely reset long-term bandwidth sampling. */ -static void bbr_reset_lt_bw_sampling(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->lt_bw = 0; - bbr->lt_use_bw = 0; - bbr->lt_is_sampling = false; - bbr_reset_lt_bw_sampling_interval(sk); -} - -/* Long-term bw sampling interval is done. Estimate whether we're policed. */ -static void bbr_lt_bw_interval_done(struct sock *sk, u32 bw) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 diff; - - if (bbr->lt_bw) { /* do we have bw from a previous interval? */ - /* Is new bw close to the lt_bw from the previous interval? */ - diff = abs(bw - bbr->lt_bw); - if ((diff * BBR_UNIT <= bbr_lt_bw_ratio * bbr->lt_bw) || - (bbr_rate_bytes_per_sec(sk, diff, BBR_UNIT) <= - bbr_lt_bw_diff)) { - /* All criteria are met; estimate we're policed. */ - bbr->lt_bw = (bw + bbr->lt_bw) >> 1; /* avg 2 intvls */ - bbr->lt_use_bw = 1; - bbr->pacing_gain = BBR_UNIT; /* try to avoid drops */ - bbr->lt_rtt_cnt = 0; - return; - } - } - bbr->lt_bw = bw; - bbr_reset_lt_bw_sampling_interval(sk); -} - -/* Token-bucket traffic policers are common (see "An Internet-Wide Analysis of - * Traffic Policing", SIGCOMM 2016). BBR detects token-bucket policers and - * explicitly models their policed rate, to reduce unnecessary losses. We - * estimate that we're policed if we see 2 consecutive sampling intervals with - * consistent throughput and high packet loss. If we think we're being policed, - * set lt_bw to the "long-term" average delivery rate from those 2 intervals. - */ - -static void bbr_lt_bw_sampling(struct sock *sk, const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 lost, delivered; - u64 bw; - u32 t; - - if (bbr->lt_use_bw) { /* already using long-term rate, lt_bw? */ - if (bbr->mode == BBR_PROBE_BW && bbr->round_start && - ++bbr->lt_rtt_cnt >= bbr_lt_bw_max_rtts) { - bbr_reset_lt_bw_sampling(sk); /* stop using lt_bw */ - bbr_reset_probe_bw_mode(sk); /* restart gain cycling */ - } - return; - } - - /* Wait for the first loss before sampling, to let the policer exhaust - * its tokens and estimate the steady-state rate allowed by the policer. - * Starting samples earlier includes bursts that over-estimate the bw. - */ - if (!bbr->lt_is_sampling) { - if (!rs->losses) - return; - bbr_reset_lt_bw_sampling_interval(sk); - bbr->lt_is_sampling = true; - } - - /* To avoid underestimates, reset sampling if we run out of data. */ - if (rs->is_app_limited) { - bbr_reset_lt_bw_sampling(sk); - return; - } - - if (bbr->round_start) - bbr->lt_rtt_cnt++; /* count round trips in this interval */ - if (bbr->lt_rtt_cnt < bbr_lt_intvl_min_rtts) - return; /* sampling interval needs to be longer */ - if (bbr->lt_rtt_cnt > 4 * bbr_lt_intvl_min_rtts) { - bbr_reset_lt_bw_sampling(sk); /* interval is too long */ - return; - } - - /* End sampling interval when a packet is lost, so we estimate the - * policer tokens were exhausted. Stopping the sampling before the - * tokens are exhausted under-estimates the policed rate. - */ - if (!rs->losses) - return; - - /* Calculate packets lost and delivered in sampling interval. */ - lost = tp->lost - bbr->lt_last_lost; - delivered = tp->delivered - bbr->lt_last_delivered; - /* Is loss rate (lost/delivered) >= lt_loss_thresh? If not, wait. */ - if (!delivered || (lost << BBR_SCALE) < bbr_lt_loss_thresh * delivered) - return; - - /* Find average delivery rate in this sampling interval. */ - t = div_u64(tp->delivered_mstamp, USEC_PER_MSEC) - bbr->lt_last_stamp; - if ((s32)t < 1) - return; /* interval is less than one ms, so wait */ - /* Check if can multiply without overflow */ - if (t >= ~0U / USEC_PER_MSEC) { - bbr_reset_lt_bw_sampling(sk); /* interval too long; reset */ - return; - } - t *= USEC_PER_MSEC; - bw = (u64)delivered * BW_UNIT; - do_div(bw, t); - bbr_lt_bw_interval_done(sk, bw); -} - -/* Estimate the bandwidth based on how fast packets are delivered */ -static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u64 bw; - - bbr->round_start = 0; - if (rs->delivered < 0 || rs->interval_us <= 0) - return; /* Not a valid observation */ - - /* See if we've reached the next RTT */ - if (!before(rs->prior_delivered, bbr->next_rtt_delivered)) { - bbr->next_rtt_delivered = tp->delivered; - bbr->rtt_cnt++; - bbr->round_start = 1; - bbr->packet_conservation = 0; - } - - bbr_lt_bw_sampling(sk, rs); - - /* Divide delivered by the interval to find a (lower bound) bottleneck - * bandwidth sample. Delivered is in packets and interval_us in uS and - * ratio will be <<1 for most connections. So delivered is first scaled. - */ - bw = (u64)rs->delivered * BW_UNIT; - do_div(bw, rs->interval_us); - - /* If this sample is application-limited, it is likely to have a very - * low delivered count that represents application behavior rather than - * the available network rate. Such a sample could drag down estimated - * bw, causing needless slow-down. Thus, to continue to send at the - * last measured network rate, we filter out app-limited samples unless - * they describe the path bw at least as well as our bw model. - * - * So the goal during app-limited phase is to proceed with the best - * network rate no matter how long. We automatically leave this - * phase when app writes faster than the network can deliver :) - */ - if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) { - /* Incorporate new sample into our max bw filter. */ - minmax_running_max(&bbr->bw, bbr_bw_rtts, bbr->rtt_cnt, bw); - } -} - -/* Estimate when the pipe is full, using the change in delivery rate: BBR - * estimates that STARTUP filled the pipe if the estimated bw hasn't changed by - * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited - * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the - * higher rwin, 3: we get higher delivery rate samples. Or transient - * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar - * design goal, but uses delay and inter-ACK spacing instead of bandwidth. - */ -static void bbr_check_full_bw_reached(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 bw_thresh; - - if (bbr_full_bw_reached(sk) || !bbr->round_start || rs->is_app_limited) - return; - - bw_thresh = (u64)bbr->full_bw * bbr_full_bw_thresh >> BBR_SCALE; - if (bbr_max_bw(sk) >= bw_thresh) { - bbr->full_bw = bbr_max_bw(sk); - bbr->full_bw_cnt = 0; - return; - } - ++bbr->full_bw_cnt; -} - -/* If pipe is probably full, drain the queue and then enter steady-state. */ -static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) { - bbr->mode = BBR_DRAIN; /* drain queue we created */ - bbr->pacing_gain = bbr_drain_gain; /* pace slow to drain */ - bbr->cwnd_gain = bbr_high_gain; /* maintain cwnd */ - } /* fall through to check if in-flight is already small: */ - if (bbr->mode == BBR_DRAIN && - tcp_packets_in_flight(tcp_sk(sk)) <= bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) - bbr_reset_probe_bw_mode(sk); /* we estimate queue is drained */ -} - -/* Estimates the windowed max degree of ack aggregation. - * This is used to provision extra in-flight data to keep sending during - * inter-ACK silences. - * - * Degree of ack aggregation is estimated as extra data acked beyond expected. - * - * max_extra_acked = "maximum recent excess data ACKed beyond max_bw * interval" - * cwnd += max_extra_acked - * - * Max extra_acked is clamped by cwnd and bw * bbr_extra_acked_max_us (100 ms). - * Max filter is an approximate sliding window of 10-20 (packet timed) round - * trips. - */ - static void bbr_update_ack_aggregation(struct sock *sk, - const struct rate_sample *rs) - { - u32 epoch_us, expected_acked, extra_acked; - struct bbr *bbr = inet_csk_ca(sk); - struct tcp_sock *tp = tcp_sk(sk); - if (!bbr_extra_acked_gain || rs->acked_sacked <= 0 || - rs->delivered < 0 || rs->interval_us <= 0) - return; - if (bbr->round_start) { - bbr->extra_acked_win_rtts = min(0x1F, - bbr->extra_acked_win_rtts + 1); - if (bbr->extra_acked_win_rtts >= bbr_extra_acked_win_rtts) { - bbr->extra_acked_win_rtts = 0; - bbr->extra_acked_win_idx = bbr->extra_acked_win_idx ?0 : 1; - bbr->extra_acked[bbr->extra_acked_win_idx] = 0; - } - } - /* Compute how many packets we expected to be delivered over epoch. */ - epoch_us = tcp_stamp_us_delta(tp->delivered_mstamp, - bbr->ack_epoch_mstamp); - expected_acked = ((u64)bbr_bw(sk) * epoch_us) / BW_UNIT; - /* Reset the aggregation epoch if ACK rate is below expected rate or - * significantly large no. of ack received since epoch (potentially - * quite old epoch). - */ - if (bbr->ack_epoch_acked <= expected_acked || - (bbr->ack_epoch_acked + rs->acked_sacked >= - bbr_ack_epoch_acked_reset_thresh)) { - bbr->ack_epoch_acked = 0; - bbr->ack_epoch_mstamp = tp->delivered_mstamp; - expected_acked = 0; - } - /* Compute excess data delivered, beyond what was expected. */ - bbr->ack_epoch_acked = min(0xFFFFFU, - bbr->ack_epoch_acked + rs->acked_sacked); - extra_acked = bbr->ack_epoch_acked - expected_acked; - extra_acked = min(extra_acked, tp->snd_cwnd); - if (extra_acked > bbr->extra_acked[bbr->extra_acked_win_idx]) - bbr->extra_acked[bbr->extra_acked_win_idx] = extra_acked; -} - -/* The goal of PROBE_RTT mode is to have BBR flows cooperatively and - * periodically drain the bottleneck queue, to converge to measure the true - * min_rtt (unloaded propagation delay). This allows the flows to keep queues - * small (reducing queuing delay and packet loss) and achieve fairness among - * BBR flows. - * - * The min_rtt filter window is 10 seconds. When the min_rtt estimate expires, - * we enter PROBE_RTT mode and cap the cwnd at bbr_cwnd_min_target=4 packets. - * After at least bbr_probe_rtt_mode_ms=200ms and at least one packet-timed - * round trip elapsed with that flight size <= 4, we leave PROBE_RTT mode and - * re-enter the previous mode. BBR uses 200ms to approximately bound the - * performance penalty of PROBE_RTT's cwnd capping to roughly 2% (200ms/10s). - * - * Note that flows need only pay 2% if they are busy sending over the last 10 - * seconds. Interactive applications (e.g., Web, RPCs, video chunks) often have - * natural silences or low-rate periods within 10 seconds where the rate is low - * enough for long enough to drain its queue in the bottleneck. We pick up - * these min RTT measurements opportunistically with our min_rtt filter. :-) - */ - -static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - bool filter_expired; - - /* Track min RTT seen in the min_rtt_win_sec filter window: */ - filter_expired = after(tcp_jiffies32, - bbr->min_rtt_stamp + bbr_min_rtt_win_sec * HZ); - if (rs->rtt_us >= 0 && - (rs->rtt_us <= bbr->min_rtt_us || filter_expired)) { - bbr->min_rtt_us = rs->rtt_us; - bbr->min_rtt_stamp = tcp_jiffies32; - } - - if (bbr_probe_rtt_mode_ms > 0 && filter_expired && - !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) { - bbr->mode = BBR_PROBE_RTT; /* dip, drain queue */ - bbr->pacing_gain = BBR_UNIT; - bbr->cwnd_gain = BBR_UNIT; - bbr_save_cwnd(sk); /* note cwnd so we can restore it */ - bbr->probe_rtt_done_stamp = 0; - } - - if (bbr->mode == BBR_PROBE_RTT) { - /* Ignore low rate samples during this mode. */ - tp->app_limited = - (tp->delivered + tcp_packets_in_flight(tp)) ? : 1; - /* Maintain min packets in flight for max(200 ms, 1 round). */ - if (!bbr->probe_rtt_done_stamp && - tcp_packets_in_flight(tp) <= bbr_cwnd_min_target) { - bbr->probe_rtt_done_stamp = tcp_jiffies32 + - msecs_to_jiffies(bbr_probe_rtt_mode_ms); - bbr->probe_rtt_round_done = 0; - bbr->next_rtt_delivered = tp->delivered; - } else if (bbr->probe_rtt_done_stamp) { - if (bbr->round_start) - bbr->probe_rtt_round_done = 1; - if (bbr->probe_rtt_round_done && - after(tcp_jiffies32, bbr->probe_rtt_done_stamp)) { - bbr->min_rtt_stamp = tcp_jiffies32; - bbr->restore_cwnd = 1; /* snap to prior_cwnd */ - bbr_reset_mode(sk); - } - } - } - bbr->idle_restart = 0; -} - -static void bbr_update_model(struct sock *sk, const struct rate_sample *rs) -{ - bbr_update_bw(sk, rs); - bbr_update_ack_aggregation(sk, rs); - bbr_update_cycle_phase(sk, rs); - bbr_check_full_bw_reached(sk, rs); - bbr_check_drain(sk, rs); - bbr_update_min_rtt(sk, rs); -} - -static void bbr_main(struct sock *sk, const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 bw; - - bbr_update_model(sk, rs); - - bw = bbr_bw(sk); - bbr_set_pacing_rate(sk, bw, bbr->pacing_gain); - bbr_set_tso_segs_goal(sk); - bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain); -} - -static void bbr_init(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr->prior_cwnd = 0; - bbr->tso_segs_goal = 0; /* default segs per skb until first ACK */ - bbr->rtt_cnt = 0; - bbr->next_rtt_delivered = 0; - bbr->prev_ca_state = TCP_CA_Open; - bbr->packet_conservation = 0; - - bbr->probe_rtt_done_stamp = 0; - bbr->probe_rtt_round_done = 0; - bbr->min_rtt_us = tcp_min_rtt(tp); - bbr->min_rtt_stamp = tcp_jiffies32; - - minmax_reset(&bbr->bw, bbr->rtt_cnt, 0); /* init max bw to 0 */ - - bbr->has_seen_rtt = 0; - bbr_init_pacing_rate_from_rtt(sk); - - bbr->restore_cwnd = 0; - bbr->round_start = 0; - bbr->idle_restart = 0; - bbr->full_bw = 0; - bbr->full_bw_cnt = 0; - bbr->cycle_mstamp = 0; - bbr->cycle_idx = 0; - bbr->cycle_len = 0; - bbr_reset_lt_bw_sampling(sk); - bbr_reset_startup_mode(sk); - bbr->ack_epoch_mstamp = tp->tcp_mstamp; - bbr->ack_epoch_acked = 0; - bbr->extra_acked_win_rtts = 0; - bbr->extra_acked_win_idx = 0; - bbr->extra_acked[0] = 0; - bbr->extra_acked[1] = 0; - - cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED); -} - -static u32 bbr_sndbuf_expand(struct sock *sk) -{ - /* Provision 3 * cwnd since BBR may slow-start even during recovery. */ - return 3; -} - -/* In theory BBR does not need to undo the cwnd since it does not - * always reduce cwnd on losses (see bbr_main()). Keep it for now. - */ -static u32 bbr_undo_cwnd(struct sock *sk) -{ - return tcp_sk(sk)->snd_cwnd; -} - -/* Entering loss recovery, so save cwnd for when we exit or undo recovery. */ -static u32 bbr_ssthresh(struct sock *sk) -{ - bbr_save_cwnd(sk); - return TCP_INFINITE_SSTHRESH; /* BBR does not use ssthresh */ -} - -static size_t bbr_get_info(struct sock *sk, u32 ext, int *attr, - union tcp_cc_info *info) -{ - if (ext & (1 << (INET_DIAG_BBRINFO - 1)) || - ext & (1 << (INET_DIAG_VEGASINFO - 1))) { - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u64 bw = bbr_bw(sk); - - bw = bw * tp->mss_cache * USEC_PER_SEC >> BW_SCALE; - memset(&info->bbr, 0, sizeof(info->bbr)); - info->bbr.bbr_bw_lo = (u32)bw; - info->bbr.bbr_bw_hi = (u32)(bw >> 32); - info->bbr.bbr_min_rtt = bbr->min_rtt_us; - info->bbr.bbr_pacing_gain = bbr->pacing_gain; - info->bbr.bbr_cwnd_gain = bbr->cwnd_gain; - *attr = INET_DIAG_BBRINFO; - return sizeof(info->bbr); - } - return 0; -} - -static void bbr_set_state(struct sock *sk, u8 new_state) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (new_state == TCP_CA_Loss) { - struct rate_sample rs = { .losses = 1 }; - - bbr->prev_ca_state = TCP_CA_Loss; - bbr->full_bw = 0; - bbr->round_start = 1; /* treat RTO like end of a round */ - bbr_lt_bw_sampling(sk, &rs); - } -} - -static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = { - .flags = TCP_CONG_NON_RESTRICTED, - .name = "bbrplus", - .owner = THIS_MODULE, - .init = bbr_init, - .cong_control = bbr_main, - .sndbuf_expand = bbr_sndbuf_expand, - .undo_cwnd = bbr_undo_cwnd, - .cwnd_event = bbr_cwnd_event, - .ssthresh = bbr_ssthresh, - .tso_segs_goal = bbr_tso_segs_goal, - .get_info = bbr_get_info, - .set_state = bbr_set_state, -}; - -static int __init bbr_register(void) -{ - BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE); - return tcp_register_congestion_control(&tcp_bbr_cong_ops); -} - -static void __exit bbr_unregister(void) -{ - tcp_unregister_congestion_control(&tcp_bbr_cong_ops); -} - -module_init(bbr_register); -module_exit(bbr_unregister); - -MODULE_AUTHOR("Van Jacobson "); -MODULE_AUTHOR("Neal Cardwell "); -MODULE_AUTHOR("Yuchung Cheng "); -MODULE_AUTHOR("Soheil Hassas Yeganeh "); -MODULE_LICENSE("Dual BSD/GPL"); -MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)");