diff options
Diffstat (limited to 'SOURCES/tkg-BBRv2.patch')
| -rw-r--r-- | SOURCES/tkg-BBRv2.patch | 3311 |
1 files changed, 0 insertions, 3311 deletions
diff --git a/SOURCES/tkg-BBRv2.patch b/SOURCES/tkg-BBRv2.patch deleted file mode 100644 index 35640e3..0000000 --- a/SOURCES/tkg-BBRv2.patch +++ /dev/null @@ -1,3311 +0,0 @@ -From eff7e1edf2fec63bac1a81f8c86295dd3f48422a Mon Sep 17 00:00:00 2001 -From: Oleksandr Natalenko <oleksandr@natalenko.name> -Date: Mon, 4 Apr 2022 08:23:19 +0200 -Subject: [PATCH] tcp_bbr2: introduce BBRv2 - -Signed-off-by: Oleksandr Natalenko <oleksandr@natalenko.name> ---- - include/linux/tcp.h | 3 +- - include/net/inet_connection_sock.h | 3 +- - include/net/tcp.h | 41 +- - include/uapi/linux/inet_diag.h | 33 + - net/ipv4/Kconfig | 22 + - net/ipv4/Makefile | 1 + - net/ipv4/tcp.c | 1 + - net/ipv4/tcp_bbr.c | 38 +- - net/ipv4/tcp_bbr2.c | 2674 ++++++++++++++++++++++++++++ - net/ipv4/tcp_cong.c | 1 + - net/ipv4/tcp_input.c | 27 +- - net/ipv4/tcp_output.c | 26 +- - net/ipv4/tcp_rate.c | 30 +- - net/ipv4/tcp_timer.c | 1 + - 14 files changed, 2867 insertions(+), 34 deletions(-) - create mode 100644 net/ipv4/tcp_bbr2.c - -diff --git a/include/linux/tcp.h b/include/linux/tcp.h -index 41b1da621a45..d8f94ef1a297 100644 ---- a/include/linux/tcp.h -+++ b/include/linux/tcp.h -@@ -255,7 +255,8 @@ struct tcp_sock { - u8 compressed_ack; - u8 dup_ack_counter:2, - tlp_retrans:1, /* TLP is a retransmission */ -- unused:5; -+ fast_ack_mode:2, /* which fast ack mode ? */ -+ unused:3; - u32 chrono_start; /* Start time in jiffies of a TCP chrono */ - u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */ - u8 chrono_type:2, /* current chronograph type */ -diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h -index c2b15f7e5516..d85858efa571 100644 ---- a/include/net/inet_connection_sock.h -+++ b/include/net/inet_connection_sock.h -@@ -135,7 +135,8 @@ struct inet_connection_sock { - u32 icsk_probes_tstamp; - u32 icsk_user_timeout; - -- u64 icsk_ca_priv[104 / sizeof(u64)]; -+/* XXX inflated by temporary internal debugging info */ -+ u64 icsk_ca_priv[216 / sizeof(u64)]; - #define ICSK_CA_PRIV_SIZE sizeof_field(struct inet_connection_sock, icsk_ca_priv) - }; - -diff --git a/include/net/tcp.h b/include/net/tcp.h -index 14d45661a84d..7261fae79403 100644 ---- a/include/net/tcp.h -+++ b/include/net/tcp.h -@@ -375,6 +375,7 @@ static inline void tcp_dec_quickack_mode(struct sock *sk, - #define TCP_ECN_QUEUE_CWR 2 - #define TCP_ECN_DEMAND_CWR 4 - #define TCP_ECN_SEEN 8 -+#define TCP_ECN_ECT_PERMANENT 16 - - enum tcp_tw_status { - TCP_TW_SUCCESS = 0, -@@ -823,6 +824,11 @@ static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) - return max_t(s64, t1 - t0, 0); - } - -+static inline u32 tcp_stamp32_us_delta(u32 t1, u32 t0) -+{ -+ return max_t(s32, t1 - t0, 0); -+} -+ - static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) - { - return tcp_ns_to_ts(skb->skb_mstamp_ns); -@@ -898,9 +904,14 @@ struct tcp_skb_cb { - /* pkts S/ACKed so far upon tx of skb, incl retrans: */ - __u32 delivered; - /* start of send pipeline phase */ -- u64 first_tx_mstamp; -+ u32 first_tx_mstamp; - /* when we reached the "delivered" count */ -- u64 delivered_mstamp; -+ u32 delivered_mstamp; -+#define TCPCB_IN_FLIGHT_BITS 20 -+#define TCPCB_IN_FLIGHT_MAX ((1U << TCPCB_IN_FLIGHT_BITS) - 1) -+ u32 in_flight:20, /* packets in flight at transmit */ -+ unused2:12; -+ u32 lost; /* packets lost so far upon tx of skb */ - } tx; /* only used for outgoing skbs */ - union { - struct inet_skb_parm h4; -@@ -1026,7 +1037,11 @@ enum tcp_ca_ack_event_flags { - #define TCP_CONG_NON_RESTRICTED 0x1 - /* Requires ECN/ECT set on all packets */ - #define TCP_CONG_NEEDS_ECN 0x2 --#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN) -+/* Wants notification of CE events (CA_EVENT_ECN_IS_CE, CA_EVENT_ECN_NO_CE). */ -+#define TCP_CONG_WANTS_CE_EVENTS 0x4 -+#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | \ -+ TCP_CONG_NEEDS_ECN | \ -+ TCP_CONG_WANTS_CE_EVENTS) - - union tcp_cc_info; - -@@ -1046,8 +1061,11 @@ struct ack_sample { - */ - struct rate_sample { - u64 prior_mstamp; /* starting timestamp for interval */ -+ u32 prior_lost; /* tp->lost at "prior_mstamp" */ - u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ - u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */ -+ u32 tx_in_flight; /* packets in flight at starting timestamp */ -+ s32 lost; /* number of packets lost over interval */ - s32 delivered; /* number of packets delivered over interval */ - s32 delivered_ce; /* number of packets delivered w/ CE marks*/ - long interval_us; /* time for tp->delivered to incr "delivered" */ -@@ -1061,6 +1079,7 @@ struct rate_sample { - bool is_app_limited; /* is sample from packet with bubble in pipe? */ - bool is_retrans; /* is sample from retransmission? */ - bool is_ack_delayed; /* is this (likely) a delayed ACK? */ -+ bool is_ece; /* did this ACK have ECN marked? */ - }; - - struct tcp_congestion_ops { -@@ -1084,8 +1103,11 @@ struct tcp_congestion_ops { - /* hook for packet ack accounting (optional) */ - void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); - -- /* override sysctl_tcp_min_tso_segs */ -- u32 (*min_tso_segs)(struct sock *sk); -+ /* pick target number of segments per TSO/GSO skb (optional): */ -+ u32 (*tso_segs)(struct sock *sk, unsigned int mss_now); -+ -+ /* react to a specific lost skb (optional) */ -+ void (*skb_marked_lost)(struct sock *sk, const struct sk_buff *skb); - - /* call when packets are delivered to update cwnd and pacing rate, - * after all the ca_state processing. (optional) -@@ -1148,6 +1170,14 @@ static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) - } - #endif - -+static inline bool tcp_ca_wants_ce_events(const struct sock *sk) -+{ -+ const struct inet_connection_sock *icsk = inet_csk(sk); -+ -+ return icsk->icsk_ca_ops->flags & (TCP_CONG_NEEDS_ECN | -+ TCP_CONG_WANTS_CE_EVENTS); -+} -+ - static inline bool tcp_ca_needs_ecn(const struct sock *sk) - { - const struct inet_connection_sock *icsk = inet_csk(sk); -@@ -1167,6 +1197,7 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) - void tcp_set_ca_state(struct sock *sk, const u8 ca_state); - - /* From tcp_rate.c */ -+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb); - void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); - void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, - struct rate_sample *rs); -diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h -index 50655de04c9b..0e24f11627d5 100644 ---- a/include/uapi/linux/inet_diag.h -+++ b/include/uapi/linux/inet_diag.h -@@ -231,9 +231,42 @@ struct tcp_bbr_info { - __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */ - }; - -+/* Phase as reported in netlink/ss stats. */ -+enum tcp_bbr2_phase { -+ BBR2_PHASE_INVALID = 0, -+ BBR2_PHASE_STARTUP = 1, -+ BBR2_PHASE_DRAIN = 2, -+ BBR2_PHASE_PROBE_RTT = 3, -+ BBR2_PHASE_PROBE_BW_UP = 4, -+ BBR2_PHASE_PROBE_BW_DOWN = 5, -+ BBR2_PHASE_PROBE_BW_CRUISE = 6, -+ BBR2_PHASE_PROBE_BW_REFILL = 7 -+}; -+ -+struct tcp_bbr2_info { -+ /* u64 bw: bandwidth (app throughput) estimate in Byte per sec: */ -+ __u32 bbr_bw_lsb; /* lower 32 bits of bw */ -+ __u32 bbr_bw_msb; /* upper 32 bits of bw */ -+ __u32 bbr_min_rtt; /* min-filtered RTT in uSec */ -+ __u32 bbr_pacing_gain; /* pacing gain shifted left 8 bits */ -+ __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */ -+ __u32 bbr_bw_hi_lsb; /* lower 32 bits of bw_hi */ -+ __u32 bbr_bw_hi_msb; /* upper 32 bits of bw_hi */ -+ __u32 bbr_bw_lo_lsb; /* lower 32 bits of bw_lo */ -+ __u32 bbr_bw_lo_msb; /* upper 32 bits of bw_lo */ -+ __u8 bbr_mode; /* current bbr_mode in state machine */ -+ __u8 bbr_phase; /* current state machine phase */ -+ __u8 unused1; /* alignment padding; not used yet */ -+ __u8 bbr_version; /* MUST be at this offset in struct */ -+ __u32 bbr_inflight_lo; /* lower/short-term data volume bound */ -+ __u32 bbr_inflight_hi; /* higher/long-term data volume bound */ -+ __u32 bbr_extra_acked; /* max excess packets ACKed in epoch */ -+}; -+ - union tcp_cc_info { - struct tcpvegas_info vegas; - struct tcp_dctcp_info dctcp; - struct tcp_bbr_info bbr; -+ struct tcp_bbr2_info bbr2; - }; - #endif /* _UAPI_INET_DIAG_H_ */ -diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig -index 2dfb12230f08..b6bec331a82e 100644 ---- a/net/ipv4/Kconfig -+++ b/net/ipv4/Kconfig -@@ -678,6 +678,24 @@ config TCP_CONG_BBR - AQM schemes that do not provide a delay signal. It requires the fq - ("Fair Queue") pacing packet scheduler. - -+config TCP_CONG_BBR2 -+ tristate "BBR2 TCP" -+ default n -+ help -+ -+ BBR2 TCP congestion control is a model-based congestion control -+ algorithm that aims to maximize network utilization, keep queues and -+ retransmit rates low, and to be able to coexist with Reno/CUBIC in -+ common scenarios. It builds an explicit model of the network path. It -+ tolerates a targeted degree of random packet loss and delay that are -+ unrelated to congestion. It can operate over LAN, WAN, cellular, wifi, -+ or cable modem links, and can use DCTCP-L4S-style ECN signals. It can -+ coexist with flows that use loss-based congestion control, and can -+ operate with shallow buffers, deep buffers, bufferbloat, policers, or -+ AQM schemes that do not provide a delay signal. It requires pacing, -+ using either TCP internal pacing or the fq ("Fair Queue") pacing packet -+ scheduler. -+ - choice - prompt "Default TCP congestion control" - default DEFAULT_CUBIC -@@ -715,6 +733,9 @@ choice - config DEFAULT_BBR - bool "BBR" if TCP_CONG_BBR=y - -+ config DEFAULT_BBR2 -+ bool "BBR2" if TCP_CONG_BBR2=y -+ - config DEFAULT_RENO - bool "Reno" - endchoice -@@ -739,6 +760,7 @@ config DEFAULT_TCP_CONG - default "dctcp" if DEFAULT_DCTCP - default "cdg" if DEFAULT_CDG - default "bbr" if DEFAULT_BBR -+ default "bbr2" if DEFAULT_BBR2 - default "cubic" - - config TCP_MD5SIG -diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile -index bbdd9c44f14e..8dee1547d820 100644 ---- a/net/ipv4/Makefile -+++ b/net/ipv4/Makefile -@@ -46,6 +46,7 @@ obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o - obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o - obj-$(CONFIG_INET_RAW_DIAG) += raw_diag.o - obj-$(CONFIG_TCP_CONG_BBR) += tcp_bbr.o -+obj-$(CONFIG_TCP_CONG_BBR2) += tcp_bbr2.o - obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o - obj-$(CONFIG_TCP_CONG_CDG) += tcp_cdg.o - obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o -diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c -index 4f2205756cfe..c139747666dd 100644 ---- a/net/ipv4/tcp.c -+++ b/net/ipv4/tcp.c -@@ -3188,6 +3188,7 @@ int tcp_disconnect(struct sock *sk, int flags) - tp->rx_opt.dsack = 0; - tp->rx_opt.num_sacks = 0; - tp->rcv_ooopack = 0; -+ tp->fast_ack_mode = 0; - - - /* Clean up fastopen related fields */ -diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c -index 54eec33c6e1c..bfbf158c71f4 100644 ---- a/net/ipv4/tcp_bbr.c -+++ b/net/ipv4/tcp_bbr.c -@@ -294,26 +294,40 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) - sk->sk_pacing_rate = rate; - } - --/* override sysctl_tcp_min_tso_segs */ - __bpf_kfunc static u32 bbr_min_tso_segs(struct sock *sk) - { - return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2; - } - -+/* Return the number of segments BBR would like in a TSO/GSO skb, given -+ * a particular max gso size as a constraint. -+ */ -+static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now, -+ u32 gso_max_size) -+{ -+ u32 segs; -+ u64 bytes; -+ -+ /* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */ -+ bytes = sk->sk_pacing_rate >> sk->sk_pacing_shift; -+ -+ bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER); -+ segs = max_t(u32, div_u64(bytes, mss_now), bbr_min_tso_segs(sk)); -+ return segs; -+} -+ -+/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */ -+static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) -+{ -+ return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size); -+} -+ -+/* Like bbr_tso_segs(), using mss_cache, ignoring driver's sk_gso_max_size. */ - static u32 bbr_tso_segs_goal(struct sock *sk) - { - struct tcp_sock *tp = tcp_sk(sk); -- u32 segs, bytes; -- -- /* Sort of tcp_tso_autosize() but ignoring -- * driver provided sk_gso_max_size. -- */ -- bytes = min_t(unsigned long, -- sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift), -- GSO_LEGACY_MAX_SIZE - 1 - MAX_TCP_HEADER); -- segs = max_t(u32, bytes / tp->mss_cache, bbr_min_tso_segs(sk)); - -- return min(segs, 0x7FU); -+ return bbr_tso_segs_generic(sk, tp->mss_cache, GSO_LEGACY_MAX_SIZE); - } - - /* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */ -@@ -1149,7 +1163,7 @@ static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = { - .undo_cwnd = bbr_undo_cwnd, - .cwnd_event = bbr_cwnd_event, - .ssthresh = bbr_ssthresh, -- .min_tso_segs = bbr_min_tso_segs, -+ .tso_segs = bbr_tso_segs, - .get_info = bbr_get_info, - .set_state = bbr_set_state, - }; -diff --git a/net/ipv4/tcp_bbr2.c b/net/ipv4/tcp_bbr2.c -new file mode 100644 -index 000000000000..488429f0f3d0 ---- /dev/null -+++ b/net/ipv4/tcp_bbr2.c -@@ -0,0 +1,2674 @@ -+/* BBR (Bottleneck Bandwidth and RTT) congestion control, v2 -+ * -+ * BBRv2 is a model-based congestion control algorithm that aims for low -+ * queues, low loss, and (bounded) Reno/CUBIC coexistence. To maintain a model -+ * of the network path, it uses measurements of bandwidth and RTT, as well as -+ * (if they occur) packet loss and/or DCTCP/L4S-style ECN signals. Note that -+ * although it can use ECN or loss signals explicitly, it does not require -+ * either; it can bound its in-flight data based on its estimate of the BDP. -+ * -+ * The model has both higher and lower bounds for the operating range: -+ * lo: bw_lo, inflight_lo: conservative short-term lower bound -+ * hi: bw_hi, inflight_hi: robust long-term upper bound -+ * The bandwidth-probing time scale is (a) extended dynamically based on -+ * estimated BDP to improve coexistence with Reno/CUBIC; (b) bounded by -+ * an interactive wall-clock time-scale to be more scalable and responsive -+ * than Reno and CUBIC. -+ * -+ * 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 <linux/module.h> -+#include <net/tcp.h> -+#include <linux/inet_diag.h> -+#include <linux/inet.h> -+#include <linux/random.h> -+ -+#include "tcp_dctcp.h" -+ -+/* 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) -+ -+#define FLAG_DEBUG_VERBOSE 0x1 /* Verbose debugging messages */ -+#define FLAG_DEBUG_LOOPBACK 0x2 /* Do NOT skip loopback addr */ -+ -+#define CYCLE_LEN 8 /* number of phases in a pacing gain cycle */ -+ -+/* 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 */ -+}; -+ -+/* How does the incoming ACK stream relate to our bandwidth probing? */ -+enum bbr_ack_phase { -+ BBR_ACKS_INIT, /* not probing; not getting probe feedback */ -+ BBR_ACKS_REFILLING, /* sending at est. bw to fill pipe */ -+ BBR_ACKS_PROBE_STARTING, /* inflight rising to probe bw */ -+ BBR_ACKS_PROBE_FEEDBACK, /* getting feedback from bw probing */ -+ BBR_ACKS_PROBE_STOPPING, /* stopped probing; still getting feedback */ -+}; -+ -+/* 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 */ -+ u32 probe_rtt_min_us; /* min RTT in bbr_probe_rtt_win_ms window */ -+ u32 probe_rtt_min_stamp; /* timestamp of probe_rtt_min_us*/ -+ u32 next_rtt_delivered; /* scb->tx.delivered at end of round */ -+ u32 prior_rcv_nxt; /* tp->rcv_nxt when CE state last changed */ -+ 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? */ -+ round_start:1, /* start of packet-timed tx->ack round? */ -+ ce_state:1, /* If most recent data has CE bit set */ -+ bw_probe_up_rounds:5, /* cwnd-limited rounds in PROBE_UP */ -+ try_fast_path:1, /* can we take fast path? */ -+ unused2:11, -+ idle_restart:1, /* restarting after idle? */ -+ probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */ -+ cycle_idx:3, /* current index in pacing_gain cycle array */ -+ has_seen_rtt:1; /* have we seen an RTT sample yet? */ -+ u32 pacing_gain:11, /* current gain for setting pacing rate */ -+ cwnd_gain:11, /* current gain for setting cwnd */ -+ full_bw_reached:1, /* reached full bw in Startup? */ -+ full_bw_cnt:2, /* number of rounds without large bw gains */ -+ init_cwnd:7; /* initial cwnd */ -+ 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 */ -+ /* BBR v2 state: */ -+ unused1:2, -+ startup_ecn_rounds:2, /* consecutive hi ECN STARTUP rounds */ -+ loss_in_cycle:1, /* packet loss in this cycle? */ -+ ecn_in_cycle:1; /* ECN in this cycle? */ -+ u32 loss_round_delivered; /* scb->tx.delivered ending loss round */ -+ u32 undo_bw_lo; /* bw_lo before latest losses */ -+ u32 undo_inflight_lo; /* inflight_lo before latest losses */ -+ u32 undo_inflight_hi; /* inflight_hi before latest losses */ -+ u32 bw_latest; /* max delivered bw in last round trip */ -+ u32 bw_lo; /* lower bound on sending bandwidth */ -+ u32 bw_hi[2]; /* upper bound of sending bandwidth range*/ -+ u32 inflight_latest; /* max delivered data in last round trip */ -+ u32 inflight_lo; /* lower bound of inflight data range */ -+ u32 inflight_hi; /* upper bound of inflight data range */ -+ u32 bw_probe_up_cnt; /* packets delivered per inflight_hi incr */ -+ u32 bw_probe_up_acks; /* packets (S)ACKed since inflight_hi incr */ -+ u32 probe_wait_us; /* PROBE_DOWN until next clock-driven probe */ -+ u32 ecn_eligible:1, /* sender can use ECN (RTT, handshake)? */ -+ ecn_alpha:9, /* EWMA delivered_ce/delivered; 0..256 */ -+ bw_probe_samples:1, /* rate samples reflect bw probing? */ -+ prev_probe_too_high:1, /* did last PROBE_UP go too high? */ -+ stopped_risky_probe:1, /* last PROBE_UP stopped due to risk? */ -+ rounds_since_probe:8, /* packet-timed rounds since probed bw */ -+ loss_round_start:1, /* loss_round_delivered round trip? */ -+ loss_in_round:1, /* loss marked in this round trip? */ -+ ecn_in_round:1, /* ECN marked in this round trip? */ -+ ack_phase:3, /* bbr_ack_phase: meaning of ACKs */ -+ loss_events_in_round:4,/* losses in STARTUP round */ -+ initialized:1; /* has bbr_init() been called? */ -+ u32 alpha_last_delivered; /* tp->delivered at alpha update */ -+ u32 alpha_last_delivered_ce; /* tp->delivered_ce at alpha update */ -+ -+ /* Params configurable using setsockopt. Refer to correspoding -+ * module param for detailed description of params. -+ */ -+ struct bbr_params { -+ u32 high_gain:11, /* max allowed value: 2047 */ -+ drain_gain:10, /* max allowed value: 1023 */ -+ cwnd_gain:11; /* max allowed value: 2047 */ -+ u32 cwnd_min_target:4, /* max allowed value: 15 */ -+ min_rtt_win_sec:5, /* max allowed value: 31 */ -+ probe_rtt_mode_ms:9, /* max allowed value: 511 */ -+ full_bw_cnt:3, /* max allowed value: 7 */ -+ cwnd_tso_budget:1, /* allowed values: {0, 1} */ -+ unused3:6, -+ drain_to_target:1, /* boolean */ -+ precise_ece_ack:1, /* boolean */ -+ extra_acked_in_startup:1, /* allowed values: {0, 1} */ -+ fast_path:1; /* boolean */ -+ u32 full_bw_thresh:10, /* max allowed value: 1023 */ -+ startup_cwnd_gain:11, /* max allowed value: 2047 */ -+ bw_probe_pif_gain:9, /* max allowed value: 511 */ -+ usage_based_cwnd:1, /* boolean */ -+ unused2:1; -+ u16 probe_rtt_win_ms:14, /* max allowed value: 16383 */ -+ refill_add_inc:2; /* max allowed value: 3 */ -+ u16 extra_acked_gain:11, /* max allowed value: 2047 */ -+ extra_acked_win_rtts:5; /* max allowed value: 31*/ -+ u16 pacing_gain[CYCLE_LEN]; /* max allowed value: 1023 */ -+ /* Mostly BBR v2 parameters below here: */ -+ u32 ecn_alpha_gain:8, /* max allowed value: 255 */ -+ ecn_factor:8, /* max allowed value: 255 */ -+ ecn_thresh:8, /* max allowed value: 255 */ -+ beta:8; /* max allowed value: 255 */ -+ u32 ecn_max_rtt_us:19, /* max allowed value: 524287 */ -+ bw_probe_reno_gain:9, /* max allowed value: 511 */ -+ full_loss_cnt:4; /* max allowed value: 15 */ -+ u32 probe_rtt_cwnd_gain:8, /* max allowed value: 255 */ -+ inflight_headroom:8, /* max allowed value: 255 */ -+ loss_thresh:8, /* max allowed value: 255 */ -+ bw_probe_max_rounds:8; /* max allowed value: 255 */ -+ u32 bw_probe_rand_rounds:4, /* max allowed value: 15 */ -+ bw_probe_base_us:26, /* usecs: 0..2^26-1 (67 secs) */ -+ full_ecn_cnt:2; /* max allowed value: 3 */ -+ u32 bw_probe_rand_us:26, /* usecs: 0..2^26-1 (67 secs) */ -+ undo:1, /* boolean */ -+ tso_rtt_shift:4, /* max allowed value: 15 */ -+ unused5:1; -+ u32 ecn_reprobe_gain:9, /* max allowed value: 511 */ -+ unused1:14, -+ ecn_alpha_init:9; /* max allowed value: 256 */ -+ } params; -+ -+ struct { -+ u32 snd_isn; /* Initial sequence number */ -+ u32 rs_bw; /* last valid rate sample bw */ -+ u32 target_cwnd; /* target cwnd, based on BDP */ -+ u8 undo:1, /* Undo even happened but not yet logged */ -+ unused:7; -+ char event; /* single-letter event debug codes */ -+ u16 unused2; -+ } debug; -+}; -+ -+struct bbr_context { -+ u32 sample_bw; -+ u32 target_cwnd; -+ u32 log:1; -+}; -+ -+/* Window length of min_rtt filter (in sec). Max allowed value is 31 (0x1F) */ -+static u32 bbr_min_rtt_win_sec = 10; -+/* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode. -+ * Max allowed value is 511 (0x1FF). -+ */ -+static u32 bbr_probe_rtt_mode_ms = 200; -+/* Window length of probe_rtt_min_us filter (in ms), and consequently the -+ * typical interval between PROBE_RTT mode entries. -+ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC -+ */ -+static u32 bbr_probe_rtt_win_ms = 5000; -+/* Skip TSO below the following bandwidth (bits/sec): */ -+static int bbr_min_tso_rate = 1200000; -+ -+/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting -+ * in bigger TSO bursts. By default we cut the RTT-based allowance in half -+ * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance -+ * is below 1500 bytes after 6 * ~500 usec = 3ms. -+ */ -+static u32 bbr_tso_rtt_shift = 9; /* halve allowance per 2^9 usecs, 512us */ -+ -+/* Select cwnd TSO budget approach: -+ * 0: padding -+ * 1: flooring -+ */ -+static uint bbr_cwnd_tso_budget = 1; -+ -+/* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck. -+ * In order to help drive the network toward lower queues and low latency while -+ * maintaining high utilization, the average pacing rate aims to be slightly -+ * lower than the estimated bandwidth. This is an important aspect of the -+ * design. -+ */ -+static const int bbr_pacing_margin_percent = 1; -+ -+/* 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. Max allowed value is 2047 (0x7FF). -+ */ -+static int bbr_high_gain = BBR_UNIT * 2885 / 1000 + 1; -+/* The gain for deriving startup cwnd. Max allowed value is 2047 (0x7FF). */ -+static int bbr_startup_cwnd_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. Max allowed value -+ * is 1023 (0x3FF). -+ */ -+static int bbr_drain_gain = BBR_UNIT * 1000 / 2885; -+/* The gain for deriving steady-state cwnd tolerates delayed/stretched ACKs. -+ * Max allowed value is 2047 (0x7FF). -+ */ -+static int bbr_cwnd_gain = BBR_UNIT * 2; -+/* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw. -+ * Max allowed value for each element is 1023 (0x3FF). -+ */ -+enum bbr_pacing_gain_phase { -+ BBR_BW_PROBE_UP = 0, /* push up inflight to probe for bw/vol */ -+ BBR_BW_PROBE_DOWN = 1, /* drain excess inflight from the queue */ -+ BBR_BW_PROBE_CRUISE = 2, /* use pipe, w/ headroom in queue/pipe */ -+ BBR_BW_PROBE_REFILL = 3, /* v2: refill the pipe again to 100% */ -+}; -+static 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... */ -+}; -+ -+/* 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. Max allowed value is 15 (0xF). -+ */ -+static u32 bbr_cwnd_min_target = 4; -+ -+/* Cwnd to BDP proportion in PROBE_RTT mode scaled by BBR_UNIT. Default: 50%. -+ * Use 0 to disable. Max allowed value is 255. -+ */ -+static u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2; -+ -+/* 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. -+ * Max allowed value is 1023 (0x3FF). -+ */ -+static u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4; -+/* But after 3 rounds w/o significant bw growth, estimate pipe is full. -+ * Max allowed value is 7 (0x7). -+ */ -+static u32 bbr_full_bw_cnt = 3; -+ -+static u32 bbr_flags; /* Debugging related stuff */ -+ -+/* Whether to debug using printk. -+ */ -+static bool bbr_debug_with_printk; -+ -+/* Whether to debug using ftrace event tcp:tcp_bbr_event. -+ * Ignored when bbr_debug_with_printk is set. -+ */ -+static bool bbr_debug_ftrace; -+ -+/* Experiment: each cycle, try to hold sub-unity gain until inflight <= BDP. */ -+static bool bbr_drain_to_target = true; /* default: enabled */ -+ -+/* Experiment: Flags to control BBR with ECN behavior. -+ */ -+static bool bbr_precise_ece_ack = true; /* default: enabled */ -+ -+/* The max rwin scaling shift factor is 14 (RFC 1323), so the max sane rwin is -+ * (2^(16+14) B)/(1024 B/packet) = 1M packets. -+ */ -+static u32 bbr_cwnd_warn_val = 1U << 20; -+ -+static u16 bbr_debug_port_mask; -+ -+/* BBR module parameters. These are module parameters only in Google prod. -+ * Upstream these are intentionally not module parameters. -+ */ -+static int bbr_pacing_gain_size = CYCLE_LEN; -+ -+/* Gain factor for adding extra_acked to target cwnd: */ -+static int bbr_extra_acked_gain = 256; -+ -+/* Window length of extra_acked window. Max allowed val is 31. */ -+static u32 bbr_extra_acked_win_rtts = 5; -+ -+/* Max allowed val for ack_epoch_acked, after which sampling epoch is reset */ -+static u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20; -+ -+/* Time period for clamping cwnd increment due to ack aggregation */ -+static u32 bbr_extra_acked_max_us = 100 * 1000; -+ -+/* Use extra acked in startup ? -+ * 0: disabled -+ * 1: use latest extra_acked value from 1-2 rtt in startup -+ */ -+static int bbr_extra_acked_in_startup = 1; /* default: enabled */ -+ -+/* Experiment: don't grow cwnd beyond twice of what we just probed. */ -+static bool bbr_usage_based_cwnd; /* default: disabled */ -+ -+/* For lab testing, researchers can enable BBRv2 ECN support with this flag, -+ * when they know that any ECN marks that the connections experience will be -+ * DCTCP/L4S-style ECN marks, rather than RFC3168 ECN marks. -+ * TODO(ncardwell): Production use of the BBRv2 ECN functionality depends on -+ * negotiation or configuration that is outside the scope of the BBRv2 -+ * alpha release. -+ */ -+static bool bbr_ecn_enable = false; -+ -+module_param_named(min_tso_rate, bbr_min_tso_rate, int, 0644); -+module_param_named(tso_rtt_shift, bbr_tso_rtt_shift, int, 0644); -+module_param_named(high_gain, bbr_high_gain, int, 0644); -+module_param_named(drain_gain, bbr_drain_gain, int, 0644); -+module_param_named(startup_cwnd_gain, bbr_startup_cwnd_gain, int, 0644); -+module_param_named(cwnd_gain, bbr_cwnd_gain, int, 0644); -+module_param_array_named(pacing_gain, bbr_pacing_gain, int, -+ &bbr_pacing_gain_size, 0644); -+module_param_named(cwnd_min_target, bbr_cwnd_min_target, uint, 0644); -+module_param_named(probe_rtt_cwnd_gain, -+ bbr_probe_rtt_cwnd_gain, uint, 0664); -+module_param_named(cwnd_warn_val, bbr_cwnd_warn_val, uint, 0664); -+module_param_named(debug_port_mask, bbr_debug_port_mask, ushort, 0644); -+module_param_named(flags, bbr_flags, uint, 0644); -+module_param_named(debug_ftrace, bbr_debug_ftrace, bool, 0644); -+module_param_named(debug_with_printk, bbr_debug_with_printk, bool, 0644); -+module_param_named(min_rtt_win_sec, bbr_min_rtt_win_sec, uint, 0644); -+module_param_named(probe_rtt_mode_ms, bbr_probe_rtt_mode_ms, uint, 0644); -+module_param_named(probe_rtt_win_ms, bbr_probe_rtt_win_ms, uint, 0644); -+module_param_named(full_bw_thresh, bbr_full_bw_thresh, uint, 0644); -+module_param_named(full_bw_cnt, bbr_full_bw_cnt, uint, 0644); -+module_param_named(cwnd_tso_bduget, bbr_cwnd_tso_budget, uint, 0664); -+module_param_named(extra_acked_gain, bbr_extra_acked_gain, int, 0664); -+module_param_named(extra_acked_win_rtts, -+ bbr_extra_acked_win_rtts, uint, 0664); -+module_param_named(extra_acked_max_us, -+ bbr_extra_acked_max_us, uint, 0664); -+module_param_named(ack_epoch_acked_reset_thresh, -+ bbr_ack_epoch_acked_reset_thresh, uint, 0664); -+module_param_named(drain_to_target, bbr_drain_to_target, bool, 0664); -+module_param_named(precise_ece_ack, bbr_precise_ece_ack, bool, 0664); -+module_param_named(extra_acked_in_startup, -+ bbr_extra_acked_in_startup, int, 0664); -+module_param_named(usage_based_cwnd, bbr_usage_based_cwnd, bool, 0664); -+module_param_named(ecn_enable, bbr_ecn_enable, bool, 0664); -+ -+static void bbr2_exit_probe_rtt(struct sock *sk); -+static void bbr2_reset_congestion_signals(struct sock *sk); -+ -+static void bbr_check_probe_rtt_done(struct sock *sk); -+ -+/* 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_reached; -+} -+ -+/* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */ -+static u32 bbr_max_bw(const struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ return max(bbr->bw_hi[0], bbr->bw_hi[1]); -+} -+ -+/* 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 min(bbr_max_bw(sk), bbr->bw_lo); -+} -+ -+/* 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 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, -+ int margin) -+{ -+ unsigned int mss = tcp_sk(sk)->mss_cache; -+ -+ rate *= mss; -+ rate *= gain; -+ rate >>= BBR_SCALE; -+ rate *= USEC_PER_SEC / 100 * (100 - margin); -+ rate >>= BW_SCALE; -+ rate = max(rate, 1ULL); -+ return rate; -+} -+ -+static u64 bbr_bw_bytes_per_sec(struct sock *sk, u64 rate) -+{ -+ return bbr_rate_bytes_per_sec(sk, rate, BBR_UNIT, 0); -+} -+ -+static u64 bbr_rate_kbps(struct sock *sk, u64 rate) -+{ -+ rate = bbr_bw_bytes_per_sec(sk, rate); -+ rate *= 8; -+ do_div(rate, 1000); -+ return rate; -+} -+ -+static u32 bbr_tso_segs_goal(struct sock *sk); -+static void bbr_debug(struct sock *sk, u32 acked, -+ const struct rate_sample *rs, struct bbr_context *ctx) -+{ -+ static const char ca_states[] = { -+ [TCP_CA_Open] = 'O', -+ [TCP_CA_Disorder] = 'D', -+ [TCP_CA_CWR] = 'C', -+ [TCP_CA_Recovery] = 'R', -+ [TCP_CA_Loss] = 'L', -+ }; -+ static const char mode[] = { -+ 'G', /* Growing - BBR_STARTUP */ -+ 'D', /* Drain - BBR_DRAIN */ -+ 'W', /* Window - BBR_PROBE_BW */ -+ 'M', /* Min RTT - BBR_PROBE_RTT */ -+ }; -+ static const char ack_phase[] = { /* bbr_ack_phase strings */ -+ 'I', /* BBR_ACKS_INIT - 'Init' */ -+ 'R', /* BBR_ACKS_REFILLING - 'Refilling' */ -+ 'B', /* BBR_ACKS_PROBE_STARTING - 'Before' */ -+ 'F', /* BBR_ACKS_PROBE_FEEDBACK - 'Feedback' */ -+ 'A', /* BBR_ACKS_PROBE_STOPPING - 'After' */ -+ }; -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ const u32 una = tp->snd_una - bbr->debug.snd_isn; -+ const u32 fack = tcp_highest_sack_seq(tp); -+ const u16 dport = ntohs(inet_sk(sk)->inet_dport); -+ bool is_port_match = (bbr_debug_port_mask && -+ ((dport & bbr_debug_port_mask) == 0)); -+ char debugmsg[320]; -+ -+ if (sk->sk_state == TCP_SYN_SENT) -+ return; /* no bbr_init() yet if SYN retransmit -> CA_Loss */ -+ -+ if (!tp->snd_cwnd || tp->snd_cwnd > bbr_cwnd_warn_val) { -+ char addr[INET6_ADDRSTRLEN + 10] = { 0 }; -+ -+ if (sk->sk_family == AF_INET) -+ snprintf(addr, sizeof(addr), "%pI4:%u", -+ &inet_sk(sk)->inet_daddr, dport); -+ else if (sk->sk_family == AF_INET6) -+ snprintf(addr, sizeof(addr), "%pI6:%u", -+ &sk->sk_v6_daddr, dport); -+ -+ WARN_ONCE(1, -+ "BBR %s cwnd alert: %u " -+ "snd_una: %u ca: %d pacing_gain: %u cwnd_gain: %u " -+ "bw: %u rtt: %u min_rtt: %u " -+ "acked: %u tso_segs: %u " -+ "bw: %d %ld %d pif: %u\n", -+ addr, tp->snd_cwnd, -+ una, inet_csk(sk)->icsk_ca_state, -+ bbr->pacing_gain, bbr->cwnd_gain, -+ bbr_max_bw(sk), (tp->srtt_us >> 3), bbr->min_rtt_us, -+ acked, bbr_tso_segs_goal(sk), -+ rs->delivered, rs->interval_us, rs->is_retrans, -+ tcp_packets_in_flight(tp)); -+ } -+ -+ if (likely(!bbr_debug_with_printk && !bbr_debug_ftrace)) -+ return; -+ -+ if (!sock_flag(sk, SOCK_DBG) && !is_port_match) -+ return; -+ -+ if (!ctx->log && !tp->app_limited && !(bbr_flags & FLAG_DEBUG_VERBOSE)) -+ return; -+ -+ if (ipv4_is_loopback(inet_sk(sk)->inet_daddr) && -+ !(bbr_flags & FLAG_DEBUG_LOOPBACK)) -+ return; -+ -+ snprintf(debugmsg, sizeof(debugmsg) - 1, -+ "BBR %pI4:%-5u %5u,%03u:%-7u %c " -+ "%c %2u br %2u cr %2d rtt %5ld d %2d i %5ld mrtt %d %cbw %llu " -+ "bw %llu lb %llu ib %llu qb %llu " -+ "a %u if %2u %c %c dl %u l %u al %u # %u t %u %c %c " -+ "lr %d er %d ea %d bwl %lld il %d ih %d c %d " -+ "v %d %c %u %c %s\n", -+ &inet_sk(sk)->inet_daddr, dport, -+ una / 1000, una % 1000, fack - tp->snd_una, -+ ca_states[inet_csk(sk)->icsk_ca_state], -+ bbr->debug.undo ? '@' : mode[bbr->mode], -+ tp->snd_cwnd, -+ bbr_extra_acked(sk), /* br (legacy): extra_acked */ -+ rs->tx_in_flight, /* cr (legacy): tx_inflight */ -+ rs->rtt_us, -+ rs->delivered, -+ rs->interval_us, -+ bbr->min_rtt_us, -+ rs->is_app_limited ? '_' : 'l', -+ bbr_rate_kbps(sk, ctx->sample_bw), /* lbw: latest sample bw */ -+ bbr_rate_kbps(sk, bbr_max_bw(sk)), /* bw: max bw */ -+ 0ULL, /* lb: [obsolete] */ -+ 0ULL, /* ib: [obsolete] */ -+ div_u64((u64)sk->sk_pacing_rate * 8, 1000), -+ acked, -+ tcp_packets_in_flight(tp), -+ rs->is_ack_delayed ? 'd' : '.', -+ bbr->round_start ? '*' : '.', -+ tp->delivered, tp->lost, -+ tp->app_limited, -+ 0, /* #: [obsolete] */ -+ ctx->target_cwnd, -+ tp->reord_seen ? 'r' : '.', /* r: reordering seen? */ -+ ca_states[bbr->prev_ca_state], -+ (rs->lost + rs->delivered) > 0 ? -+ (1000 * rs->lost / -+ (rs->lost + rs->delivered)) : 0, /* lr: loss rate x1000 */ -+ (rs->delivered) > 0 ? -+ (1000 * rs->delivered_ce / -+ (rs->delivered)) : 0, /* er: ECN rate x1000 */ -+ 1000 * bbr->ecn_alpha >> BBR_SCALE, /* ea: ECN alpha x1000 */ -+ bbr->bw_lo == ~0U ? -+ -1 : (s64)bbr_rate_kbps(sk, bbr->bw_lo), /* bwl */ -+ bbr->inflight_lo, /* il */ -+ bbr->inflight_hi, /* ih */ -+ bbr->bw_probe_up_cnt, /* c */ -+ 2, /* v: version */ -+ bbr->debug.event, -+ bbr->cycle_idx, -+ ack_phase[bbr->ack_phase], -+ bbr->bw_probe_samples ? "Y" : "N"); -+ debugmsg[sizeof(debugmsg) - 1] = 0; -+ -+ /* printk takes a higher precedence. */ -+ if (bbr_debug_with_printk) -+ printk(KERN_DEBUG "%s", debugmsg); -+ -+ if (unlikely(bbr->debug.undo)) -+ bbr->debug.undo = 0; -+} -+ -+/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */ -+static unsigned long bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain) -+{ -+ u64 rate = bw; -+ -+ rate = bbr_rate_bytes_per_sec(sk, rate, gain, -+ bbr_pacing_margin_percent); -+ 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->params.high_gain); -+} -+ -+/* Pace using current bw estimate and a gain factor. */ -+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); -+ unsigned long 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; -+} -+ -+static u32 bbr_min_tso_segs(struct sock *sk) -+{ -+ return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2; -+} -+ -+/* Return the number of segments BBR would like in a TSO/GSO skb, given -+ * a particular max gso size as a constraint. -+ */ -+static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now, -+ u32 gso_max_size) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 segs, r; -+ u64 bytes; -+ -+ /* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */ -+ bytes = sk->sk_pacing_rate >> sk->sk_pacing_shift; -+ -+ /* Budget a TSO/GSO burst size allowance based on min_rtt. For every -+ * K = 2^tso_rtt_shift microseconds of min_rtt, halve the burst. -+ * The min_rtt-based burst allowance is: 64 KBytes / 2^(min_rtt/K) -+ */ -+ if (bbr->params.tso_rtt_shift) { -+ r = bbr->min_rtt_us >> bbr->params.tso_rtt_shift; -+ if (r < BITS_PER_TYPE(u32)) /* prevent undefined behavior */ -+ bytes += GSO_MAX_SIZE >> r; -+ } -+ -+ bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER); -+ segs = max_t(u32, div_u64(bytes, mss_now), bbr_min_tso_segs(sk)); -+ return segs; -+} -+ -+/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */ -+static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) -+{ -+ return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size); -+} -+ -+/* Like bbr_tso_segs(), using mss_cache, ignoring driver's sk_gso_max_size. */ -+static u32 bbr_tso_segs_goal(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ -+ return bbr_tso_segs_generic(sk, tp->mss_cache, GSO_MAX_SIZE); -+} -+ -+/* 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); -+ else if (bbr->mode == BBR_PROBE_RTT) -+ bbr_check_probe_rtt_done(sk); -+ } else if ((event == CA_EVENT_ECN_IS_CE || -+ event == CA_EVENT_ECN_NO_CE) && -+ bbr_ecn_enable && -+ bbr->params.precise_ece_ack) { -+ u32 state = bbr->ce_state; -+ dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state); -+ bbr->ce_state = state; -+ if (tp->fast_ack_mode == 2 && event == CA_EVENT_ECN_IS_CE) -+ tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS); -+ } -+} -+ -+/* Calculate bdp based on min RTT and the estimated bottleneck bandwidth: -+ * -+ * bdp = ceil(bw * min_rtt * 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. -+ */ -+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: initial cwnd. -+ */ -+ if (unlikely(bbr->min_rtt_us == ~0U)) /* no valid RTT samples yet? */ -+ return bbr->init_cwnd; /* be safe: cap at initial cwnd */ -+ -+ w = (u64)bw * bbr->min_rtt_us; -+ -+ /* Apply a gain to the given value, remove the BW_SCALE shift, and -+ * round the value up to avoid a negative feedback loop. -+ */ -+ bdp = (((w * gain) >> BBR_SCALE) + BW_UNIT - 1) / BW_UNIT; -+ -+ return bdp; -+} -+ -+/* 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_quantization_budget(struct sock *sk, u32 cwnd) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 tso_segs_goal; -+ -+ tso_segs_goal = 3 * bbr_tso_segs_goal(sk); -+ -+ /* Allow enough full-sized skbs in flight to utilize end systems. */ -+ if (bbr->params.cwnd_tso_budget == 1) { -+ cwnd = max_t(u32, cwnd, tso_segs_goal); -+ cwnd = max_t(u32, cwnd, bbr->params.cwnd_min_target); -+ } else { -+ cwnd += tso_segs_goal; -+ cwnd = (cwnd + 1) & ~1U; -+ } -+ /* Ensure gain cycling gets inflight above BDP even for small BDPs. */ -+ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) -+ cwnd += 2; -+ -+ return cwnd; -+} -+ -+/* Find inflight based on min RTT and the estimated bottleneck bandwidth. */ -+static u32 bbr_inflight(struct sock *sk, u32 bw, int gain) -+{ -+ u32 inflight; -+ -+ inflight = bbr_bdp(sk, bw, gain); -+ inflight = bbr_quantization_budget(sk, inflight); -+ -+ return inflight; -+} -+ -+/* With pacing at lower layers, there's often less data "in the network" than -+ * "in flight". With TSQ and departure time pacing at lower layers (e.g. fq), -+ * we often have several skbs queued in the pacing layer with a pre-scheduled -+ * earliest departure time (EDT). BBR adapts its pacing rate based on the -+ * inflight level that it estimates has already been "baked in" by previous -+ * departure time decisions. We calculate a rough estimate of the number of our -+ * packets that might be in the network at the earliest departure time for the -+ * next skb scheduled: -+ * in_network_at_edt = inflight_at_edt - (EDT - now) * bw -+ * If we're increasing inflight, then we want to know if the transmit of the -+ * EDT skb will push inflight above the target, so inflight_at_edt includes -+ * bbr_tso_segs_goal() from the skb departing at EDT. If decreasing inflight, -+ * then estimate if inflight will sink too low just before the EDT transmit. -+ */ -+static u32 bbr_packets_in_net_at_edt(struct sock *sk, u32 inflight_now) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u64 now_ns, edt_ns, interval_us; -+ u32 interval_delivered, inflight_at_edt; -+ -+ now_ns = tp->tcp_clock_cache; -+ edt_ns = max(tp->tcp_wstamp_ns, now_ns); -+ interval_us = div_u64(edt_ns - now_ns, NSEC_PER_USEC); -+ interval_delivered = (u64)bbr_bw(sk) * interval_us >> BW_SCALE; -+ inflight_at_edt = inflight_now; -+ if (bbr->pacing_gain > BBR_UNIT) /* increasing inflight */ -+ inflight_at_edt += bbr_tso_segs_goal(sk); /* include EDT skb */ -+ if (interval_delivered >= inflight_at_edt) -+ return 0; -+ return inflight_at_edt - interval_delivered; -+} -+ -+/* Find the cwnd increment based on estimate of ack aggregation */ -+static u32 bbr_ack_aggregation_cwnd(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 max_aggr_cwnd, aggr_cwnd = 0; -+ -+ if (bbr->params.extra_acked_gain && -+ (bbr_full_bw_reached(sk) || bbr->params.extra_acked_in_startup)) { -+ max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us) -+ / BW_UNIT; -+ aggr_cwnd = (bbr->params.extra_acked_gain * bbr_extra_acked(sk)) -+ >> BBR_SCALE; -+ aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd); -+ } -+ -+ return aggr_cwnd; -+} -+ -+/* Returns the cwnd for PROBE_RTT mode. */ -+static u32 bbr_probe_rtt_cwnd(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (bbr->params.probe_rtt_cwnd_gain == 0) -+ return bbr->params.cwnd_min_target; -+ return max_t(u32, bbr->params.cwnd_min_target, -+ bbr_bdp(sk, bbr_bw(sk), bbr->params.probe_rtt_cwnd_gain)); -+} -+ -+/* 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, u32 cwnd, -+ struct bbr_context *ctx) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 target_cwnd = 0, prev_cwnd = tp->snd_cwnd, max_probe; -+ -+ if (!acked) -+ goto done; /* no packet fully ACKed; just apply caps */ -+ -+ 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); -+ -+ /* If we're below target cwnd, slow start cwnd toward target cwnd. */ -+ bbr->debug.target_cwnd = target_cwnd; -+ -+ /* Update cwnd and enable fast path if cwnd reaches target_cwnd. */ -+ bbr->try_fast_path = 0; -+ if (bbr_full_bw_reached(sk)) { /* only cut cwnd if we filled the pipe */ -+ cwnd += acked; -+ if (cwnd >= target_cwnd) { -+ cwnd = target_cwnd; -+ bbr->try_fast_path = 1; -+ } -+ } else if (cwnd < target_cwnd || cwnd < 2 * bbr->init_cwnd) { -+ cwnd += acked; -+ } else { -+ bbr->try_fast_path = 1; -+ } -+ -+ /* When growing cwnd, don't grow beyond twice what we just probed. */ -+ if (bbr->params.usage_based_cwnd) { -+ max_probe = max(2 * tp->max_packets_out, tp->snd_cwnd); -+ cwnd = min(cwnd, max_probe); -+ } -+ -+ cwnd = max_t(u32, cwnd, bbr->params.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_t(u32, tp->snd_cwnd, bbr_probe_rtt_cwnd(sk)); -+ -+ ctx->target_cwnd = target_cwnd; -+ ctx->log = (tp->snd_cwnd != prev_cwnd); -+} -+ -+/* See if we have reached next round trip */ -+static void bbr_update_round_start(struct sock *sk, -+ const struct rate_sample *rs, struct bbr_context *ctx) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->round_start = 0; -+ -+ /* See if we've reached the next RTT */ -+ if (rs->interval_us > 0 && -+ !before(rs->prior_delivered, bbr->next_rtt_delivered)) { -+ bbr->next_rtt_delivered = tp->delivered; -+ bbr->round_start = 1; -+ } -+} -+ -+/* Calculate the bandwidth based on how fast packets are delivered */ -+static void bbr_calculate_bw_sample(struct sock *sk, -+ const struct rate_sample *rs, struct bbr_context *ctx) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u64 bw = 0; -+ -+ /* 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. -+ * Round up to allow growth at low rates, even with integer division. -+ */ -+ if (rs->interval_us > 0) { -+ if (WARN_ONCE(rs->delivered < 0, -+ "negative delivered: %d interval_us: %ld\n", -+ rs->delivered, rs->interval_us)) -+ return; -+ -+ bw = DIV_ROUND_UP_ULL((u64)rs->delivered * BW_UNIT, rs->interval_us); -+ } -+ -+ ctx->sample_bw = bw; -+ bbr->debug.rs_bw = bw; -+} -+ -+/* 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 5-10 (packet timed) round -+ * trips for non-startup phase, and 1-2 round trips for startup. -+ */ -+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); -+ u32 extra_acked_win_rtts_thresh = bbr->params.extra_acked_win_rtts; -+ -+ if (!bbr->params.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->params.extra_acked_in_startup && -+ !bbr_full_bw_reached(sk)) -+ extra_acked_win_rtts_thresh = 1; -+ if (bbr->extra_acked_win_rtts >= -+ extra_acked_win_rtts_thresh) { -+ 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_t(u32, 0xFFFFF, -+ 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; -+} -+ -+/* 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->params.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; -+ bbr->full_bw_reached = bbr->full_bw_cnt >= bbr->params.full_bw_cnt; -+} -+ -+/* If pipe is probably full, drain the queue and then enter steady-state. */ -+static bool bbr_check_drain(struct sock *sk, const struct rate_sample *rs, -+ struct bbr_context *ctx) -+{ -+ 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 */ -+ tcp_sk(sk)->snd_ssthresh = -+ bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); -+ bbr2_reset_congestion_signals(sk); -+ } /* fall through to check if in-flight is already small: */ -+ if (bbr->mode == BBR_DRAIN && -+ bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <= -+ bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) -+ return true; /* exiting DRAIN now */ -+ return false; -+} -+ -+static void bbr_check_probe_rtt_done(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (!(bbr->probe_rtt_done_stamp && -+ after(tcp_jiffies32, bbr->probe_rtt_done_stamp))) -+ return; -+ -+ bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */ -+ tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd); -+ bbr2_exit_probe_rtt(sk); -+} -+ -+/* 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 probe_rtt_expired, min_rtt_expired; -+ u32 expire; -+ -+ /* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */ -+ expire = bbr->probe_rtt_min_stamp + -+ msecs_to_jiffies(bbr->params.probe_rtt_win_ms); -+ probe_rtt_expired = after(tcp_jiffies32, expire); -+ if (rs->rtt_us >= 0 && -+ (rs->rtt_us <= bbr->probe_rtt_min_us || -+ (probe_rtt_expired && !rs->is_ack_delayed))) { -+ bbr->probe_rtt_min_us = rs->rtt_us; -+ bbr->probe_rtt_min_stamp = tcp_jiffies32; -+ } -+ /* Track min RTT seen in the min_rtt_win_sec filter window: */ -+ expire = bbr->min_rtt_stamp + bbr->params.min_rtt_win_sec * HZ; -+ min_rtt_expired = after(tcp_jiffies32, expire); -+ if (bbr->probe_rtt_min_us <= bbr->min_rtt_us || -+ min_rtt_expired) { -+ bbr->min_rtt_us = bbr->probe_rtt_min_us; -+ bbr->min_rtt_stamp = bbr->probe_rtt_min_stamp; -+ } -+ -+ if (bbr->params.probe_rtt_mode_ms > 0 && probe_rtt_expired && -+ !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) { -+ bbr->mode = BBR_PROBE_RTT; /* dip, drain queue */ -+ bbr_save_cwnd(sk); /* note cwnd so we can restore it */ -+ bbr->probe_rtt_done_stamp = 0; -+ bbr->ack_phase = BBR_ACKS_PROBE_STOPPING; -+ bbr->next_rtt_delivered = tp->delivered; -+ } -+ -+ 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_probe_rtt_cwnd(sk)) { -+ bbr->probe_rtt_done_stamp = tcp_jiffies32 + -+ msecs_to_jiffies(bbr->params.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) -+ bbr_check_probe_rtt_done(sk); -+ } -+ } -+ /* Restart after idle ends only once we process a new S/ACK for data */ -+ if (rs->delivered > 0) -+ bbr->idle_restart = 0; -+} -+ -+static void bbr_update_gains(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ switch (bbr->mode) { -+ case BBR_STARTUP: -+ bbr->pacing_gain = bbr->params.high_gain; -+ bbr->cwnd_gain = bbr->params.startup_cwnd_gain; -+ break; -+ case BBR_DRAIN: -+ bbr->pacing_gain = bbr->params.drain_gain; /* slow, to drain */ -+ bbr->cwnd_gain = bbr->params.startup_cwnd_gain; /* keep cwnd */ -+ break; -+ case BBR_PROBE_BW: -+ bbr->pacing_gain = bbr->params.pacing_gain[bbr->cycle_idx]; -+ bbr->cwnd_gain = bbr->params.cwnd_gain; -+ break; -+ case BBR_PROBE_RTT: -+ bbr->pacing_gain = BBR_UNIT; -+ bbr->cwnd_gain = BBR_UNIT; -+ break; -+ default: -+ WARN_ONCE(1, "BBR bad mode: %u\n", bbr->mode); -+ break; -+ } -+} -+ -+static void bbr_init(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ int i; -+ -+ WARN_ON_ONCE(tp->snd_cwnd >= bbr_cwnd_warn_val); -+ -+ bbr->initialized = 1; -+ bbr->params.high_gain = min(0x7FF, bbr_high_gain); -+ bbr->params.drain_gain = min(0x3FF, bbr_drain_gain); -+ bbr->params.startup_cwnd_gain = min(0x7FF, bbr_startup_cwnd_gain); -+ bbr->params.cwnd_gain = min(0x7FF, bbr_cwnd_gain); -+ bbr->params.cwnd_tso_budget = min(0x1U, bbr_cwnd_tso_budget); -+ bbr->params.cwnd_min_target = min(0xFU, bbr_cwnd_min_target); -+ bbr->params.min_rtt_win_sec = min(0x1FU, bbr_min_rtt_win_sec); -+ bbr->params.probe_rtt_mode_ms = min(0x1FFU, bbr_probe_rtt_mode_ms); -+ bbr->params.full_bw_cnt = min(0x7U, bbr_full_bw_cnt); -+ bbr->params.full_bw_thresh = min(0x3FFU, bbr_full_bw_thresh); -+ bbr->params.extra_acked_gain = min(0x7FF, bbr_extra_acked_gain); -+ bbr->params.extra_acked_win_rtts = min(0x1FU, bbr_extra_acked_win_rtts); -+ bbr->params.drain_to_target = bbr_drain_to_target ? 1 : 0; -+ bbr->params.precise_ece_ack = bbr_precise_ece_ack ? 1 : 0; -+ bbr->params.extra_acked_in_startup = bbr_extra_acked_in_startup ? 1 : 0; -+ bbr->params.probe_rtt_cwnd_gain = min(0xFFU, bbr_probe_rtt_cwnd_gain); -+ bbr->params.probe_rtt_win_ms = -+ min(0x3FFFU, -+ min_t(u32, bbr_probe_rtt_win_ms, -+ bbr->params.min_rtt_win_sec * MSEC_PER_SEC)); -+ for (i = 0; i < CYCLE_LEN; i++) -+ bbr->params.pacing_gain[i] = min(0x3FF, bbr_pacing_gain[i]); -+ bbr->params.usage_based_cwnd = bbr_usage_based_cwnd ? 1 : 0; -+ bbr->params.tso_rtt_shift = min(0xFU, bbr_tso_rtt_shift); -+ -+ bbr->debug.snd_isn = tp->snd_una; -+ bbr->debug.target_cwnd = 0; -+ bbr->debug.undo = 0; -+ -+ bbr->init_cwnd = min(0x7FU, tp->snd_cwnd); -+ bbr->prior_cwnd = tp->prior_cwnd; -+ tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; -+ 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->probe_rtt_min_us = tcp_min_rtt(tp); -+ bbr->probe_rtt_min_stamp = tcp_jiffies32; -+ bbr->min_rtt_us = tcp_min_rtt(tp); -+ bbr->min_rtt_stamp = tcp_jiffies32; -+ -+ bbr->has_seen_rtt = 0; -+ bbr_init_pacing_rate_from_rtt(sk); -+ -+ bbr->round_start = 0; -+ bbr->idle_restart = 0; -+ bbr->full_bw_reached = 0; -+ bbr->full_bw = 0; -+ bbr->full_bw_cnt = 0; -+ bbr->cycle_mstamp = 0; -+ bbr->cycle_idx = 0; -+ bbr->mode = BBR_STARTUP; -+ bbr->debug.rs_bw = 0; -+ -+ 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; -+ -+ bbr->ce_state = 0; -+ bbr->prior_rcv_nxt = tp->rcv_nxt; -+ bbr->try_fast_path = 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; -+} -+ -+/* __________________________________________________________________________ -+ * -+ * Functions new to BBR v2 ("bbr") congestion control are below here. -+ * __________________________________________________________________________ -+ */ -+ -+/* Incorporate a new bw sample into the current window of our max filter. */ -+static void bbr2_take_bw_hi_sample(struct sock *sk, u32 bw) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]); -+} -+ -+/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */ -+static void bbr2_advance_bw_hi_filter(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (!bbr->bw_hi[1]) -+ return; /* no samples in this window; remember old window */ -+ bbr->bw_hi[0] = bbr->bw_hi[1]; -+ bbr->bw_hi[1] = 0; -+} -+ -+/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */ -+static u32 bbr2_target_inflight(struct sock *sk) -+{ -+ u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT); -+ -+ return min(bdp, tcp_sk(sk)->snd_cwnd); -+} -+ -+static bool bbr2_is_probing_bandwidth(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ return (bbr->mode == BBR_STARTUP) || -+ (bbr->mode == BBR_PROBE_BW && -+ (bbr->cycle_idx == BBR_BW_PROBE_REFILL || -+ bbr->cycle_idx == BBR_BW_PROBE_UP)); -+} -+ -+/* Has the given amount of time elapsed since we marked the phase start? */ -+static bool bbr2_has_elapsed_in_phase(const struct sock *sk, u32 interval_us) -+{ -+ const struct tcp_sock *tp = tcp_sk(sk); -+ const struct bbr *bbr = inet_csk_ca(sk); -+ -+ return tcp_stamp_us_delta(tp->tcp_mstamp, -+ bbr->cycle_mstamp + interval_us) > 0; -+} -+ -+static void bbr2_handle_queue_too_high_in_startup(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->full_bw_reached = 1; -+ bbr->inflight_hi = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); -+} -+ -+/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */ -+static void bbr2_check_ecn_too_high_in_startup(struct sock *sk, u32 ce_ratio) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (bbr_full_bw_reached(sk) || !bbr->ecn_eligible || -+ !bbr->params.full_ecn_cnt || !bbr->params.ecn_thresh) -+ return; -+ -+ if (ce_ratio >= bbr->params.ecn_thresh) -+ bbr->startup_ecn_rounds++; -+ else -+ bbr->startup_ecn_rounds = 0; -+ -+ if (bbr->startup_ecn_rounds >= bbr->params.full_ecn_cnt) { -+ bbr->debug.event = 'E'; /* ECN caused STARTUP exit */ -+ bbr2_handle_queue_too_high_in_startup(sk); -+ return; -+ } -+} -+ -+static void bbr2_update_ecn_alpha(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ s32 delivered, delivered_ce; -+ u64 alpha, ce_ratio; -+ u32 gain; -+ -+ if (bbr->params.ecn_factor == 0) -+ return; -+ -+ delivered = tp->delivered - bbr->alpha_last_delivered; -+ delivered_ce = tp->delivered_ce - bbr->alpha_last_delivered_ce; -+ -+ if (delivered == 0 || /* avoid divide by zero */ -+ WARN_ON_ONCE(delivered < 0 || delivered_ce < 0)) /* backwards? */ -+ return; -+ -+ /* See if we should use ECN sender logic for this connection. */ -+ if (!bbr->ecn_eligible && bbr_ecn_enable && -+ (bbr->min_rtt_us <= bbr->params.ecn_max_rtt_us || -+ !bbr->params.ecn_max_rtt_us)) -+ bbr->ecn_eligible = 1; -+ -+ ce_ratio = (u64)delivered_ce << BBR_SCALE; -+ do_div(ce_ratio, delivered); -+ gain = bbr->params.ecn_alpha_gain; -+ alpha = ((BBR_UNIT - gain) * bbr->ecn_alpha) >> BBR_SCALE; -+ alpha += (gain * ce_ratio) >> BBR_SCALE; -+ bbr->ecn_alpha = min_t(u32, alpha, BBR_UNIT); -+ -+ bbr->alpha_last_delivered = tp->delivered; -+ bbr->alpha_last_delivered_ce = tp->delivered_ce; -+ -+ bbr2_check_ecn_too_high_in_startup(sk, ce_ratio); -+} -+ -+/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */ -+static void bbr2_raise_inflight_hi_slope(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 growth_this_round, cnt; -+ -+ /* Calculate "slope": packets S/Acked per inflight_hi increment. */ -+ growth_this_round = 1 << bbr->bw_probe_up_rounds; -+ bbr->bw_probe_up_rounds = min(bbr->bw_probe_up_rounds + 1, 30); -+ cnt = tp->snd_cwnd / growth_this_round; -+ cnt = max(cnt, 1U); -+ bbr->bw_probe_up_cnt = cnt; -+ bbr->debug.event = 'G'; /* Grow inflight_hi slope */ -+} -+ -+/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */ -+static void bbr2_probe_inflight_hi_upward(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 delta; -+ -+ if (!tp->is_cwnd_limited || tp->snd_cwnd < bbr->inflight_hi) { -+ bbr->bw_probe_up_acks = 0; /* don't accmulate unused credits */ -+ return; /* not fully using inflight_hi, so don't grow it */ -+ } -+ -+ /* For each bw_probe_up_cnt packets ACKed, increase inflight_hi by 1. */ -+ bbr->bw_probe_up_acks += rs->acked_sacked; -+ if (bbr->bw_probe_up_acks >= bbr->bw_probe_up_cnt) { -+ delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt; -+ bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt; -+ bbr->inflight_hi += delta; -+ bbr->debug.event = 'I'; /* Increment inflight_hi */ -+ } -+ -+ if (bbr->round_start) -+ bbr2_raise_inflight_hi_slope(sk); -+} -+ -+/* Does loss/ECN rate for this sample say inflight is "too high"? -+ * This is used by both the bbr_check_loss_too_high_in_startup() function, -+ * which can be used in either v1 or v2, and the PROBE_UP phase of v2, which -+ * uses it to notice when loss/ECN rates suggest inflight is too high. -+ */ -+static bool bbr2_is_inflight_too_high(const struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ const struct bbr *bbr = inet_csk_ca(sk); -+ u32 loss_thresh, ecn_thresh; -+ -+ if (rs->lost > 0 && rs->tx_in_flight) { -+ loss_thresh = (u64)rs->tx_in_flight * bbr->params.loss_thresh >> -+ BBR_SCALE; -+ if (rs->lost > loss_thresh) -+ return true; -+ } -+ -+ if (rs->delivered_ce > 0 && rs->delivered > 0 && -+ bbr->ecn_eligible && bbr->params.ecn_thresh) { -+ ecn_thresh = (u64)rs->delivered * bbr->params.ecn_thresh >> -+ BBR_SCALE; -+ if (rs->delivered_ce >= ecn_thresh) -+ return true; -+ } -+ -+ return false; -+} -+ -+/* Calculate the tx_in_flight level that corresponded to excessive loss. -+ * We find "lost_prefix" segs of the skb where loss rate went too high, -+ * by solving for "lost_prefix" in the following equation: -+ * lost / inflight >= loss_thresh -+ * (lost_prev + lost_prefix) / (inflight_prev + lost_prefix) >= loss_thresh -+ * Then we take that equation, convert it to fixed point, and -+ * round up to the nearest packet. -+ */ -+static u32 bbr2_inflight_hi_from_lost_skb(const struct sock *sk, -+ const struct rate_sample *rs, -+ const struct sk_buff *skb) -+{ -+ const struct bbr *bbr = inet_csk_ca(sk); -+ u32 loss_thresh = bbr->params.loss_thresh; -+ u32 pcount, divisor, inflight_hi; -+ s32 inflight_prev, lost_prev; -+ u64 loss_budget, lost_prefix; -+ -+ pcount = tcp_skb_pcount(skb); -+ -+ /* How much data was in flight before this skb? */ -+ inflight_prev = rs->tx_in_flight - pcount; -+ if (WARN_ONCE(inflight_prev < 0, -+ "tx_in_flight: %u pcount: %u reneg: %u", -+ rs->tx_in_flight, pcount, tcp_sk(sk)->is_sack_reneg)) -+ return ~0U; -+ -+ /* How much inflight data was marked lost before this skb? */ -+ lost_prev = rs->lost - pcount; -+ if (WARN_ON_ONCE(lost_prev < 0)) -+ return ~0U; -+ -+ /* At what prefix of this lost skb did losss rate exceed loss_thresh? */ -+ loss_budget = (u64)inflight_prev * loss_thresh + BBR_UNIT - 1; -+ loss_budget >>= BBR_SCALE; -+ if (lost_prev >= loss_budget) { -+ lost_prefix = 0; /* previous losses crossed loss_thresh */ -+ } else { -+ lost_prefix = loss_budget - lost_prev; -+ lost_prefix <<= BBR_SCALE; -+ divisor = BBR_UNIT - loss_thresh; -+ if (WARN_ON_ONCE(!divisor)) /* loss_thresh is 8 bits */ -+ return ~0U; -+ do_div(lost_prefix, divisor); -+ } -+ -+ inflight_hi = inflight_prev + lost_prefix; -+ return inflight_hi; -+} -+ -+/* If loss/ECN rates during probing indicated we may have overfilled a -+ * buffer, return an operating point that tries to leave unutilized headroom in -+ * the path for other flows, for fairness convergence and lower RTTs and loss. -+ */ -+static u32 bbr2_inflight_with_headroom(const struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 headroom, headroom_fraction; -+ -+ if (bbr->inflight_hi == ~0U) -+ return ~0U; -+ -+ headroom_fraction = bbr->params.inflight_headroom; -+ headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE; -+ headroom = max(headroom, 1U); -+ return max_t(s32, bbr->inflight_hi - headroom, -+ bbr->params.cwnd_min_target); -+} -+ -+/* Bound cwnd to a sensible level, based on our current probing state -+ * machine phase and model of a good inflight level (inflight_lo, inflight_hi). -+ */ -+static void bbr2_bound_cwnd_for_inflight_model(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 cap; -+ -+ /* tcp_rcv_synsent_state_process() currently calls tcp_ack() -+ * and thus cong_control() without first initializing us(!). -+ */ -+ if (!bbr->initialized) -+ return; -+ -+ cap = ~0U; -+ if (bbr->mode == BBR_PROBE_BW && -+ bbr->cycle_idx != BBR_BW_PROBE_CRUISE) { -+ /* Probe to see if more packets fit in the path. */ -+ cap = bbr->inflight_hi; -+ } else { -+ if (bbr->mode == BBR_PROBE_RTT || -+ (bbr->mode == BBR_PROBE_BW && -+ bbr->cycle_idx == BBR_BW_PROBE_CRUISE)) -+ cap = bbr2_inflight_with_headroom(sk); -+ } -+ /* Adapt to any loss/ECN since our last bw probe. */ -+ cap = min(cap, bbr->inflight_lo); -+ -+ cap = max_t(u32, cap, bbr->params.cwnd_min_target); -+ tp->snd_cwnd = min(cap, tp->snd_cwnd); -+} -+ -+/* Estimate a short-term lower bound on the capacity available now, based -+ * on measurements of the current delivery process and recent history. When we -+ * are seeing loss/ECN at times when we are not probing bw, then conservatively -+ * move toward flow balance by multiplicatively cutting our short-term -+ * estimated safe rate and volume of data (bw_lo and inflight_lo). We use a -+ * multiplicative decrease in order to converge to a lower capacity in time -+ * logarithmic in the magnitude of the decrease. -+ * -+ * However, we do not cut our short-term estimates lower than the current rate -+ * and volume of delivered data from this round trip, since from the current -+ * delivery process we can estimate the measured capacity available now. -+ * -+ * Anything faster than that approach would knowingly risk high loss, which can -+ * cause low bw for Reno/CUBIC and high loss recovery latency for -+ * request/response flows using any congestion control. -+ */ -+static void bbr2_adapt_lower_bounds(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 ecn_cut, ecn_inflight_lo, beta; -+ -+ /* We only use lower-bound estimates when not probing bw. -+ * When probing we need to push inflight higher to probe bw. -+ */ -+ if (bbr2_is_probing_bandwidth(sk)) -+ return; -+ -+ /* ECN response. */ -+ if (bbr->ecn_in_round && bbr->ecn_eligible && bbr->params.ecn_factor) { -+ /* Reduce inflight to (1 - alpha*ecn_factor). */ -+ ecn_cut = (BBR_UNIT - -+ ((bbr->ecn_alpha * bbr->params.ecn_factor) >> -+ BBR_SCALE)); -+ if (bbr->inflight_lo == ~0U) -+ bbr->inflight_lo = tp->snd_cwnd; -+ ecn_inflight_lo = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE; -+ } else { -+ ecn_inflight_lo = ~0U; -+ } -+ -+ /* Loss response. */ -+ if (bbr->loss_in_round) { -+ /* Reduce bw and inflight to (1 - beta). */ -+ if (bbr->bw_lo == ~0U) -+ bbr->bw_lo = bbr_max_bw(sk); -+ if (bbr->inflight_lo == ~0U) -+ bbr->inflight_lo = tp->snd_cwnd; -+ beta = bbr->params.beta; -+ bbr->bw_lo = -+ max_t(u32, bbr->bw_latest, -+ (u64)bbr->bw_lo * -+ (BBR_UNIT - beta) >> BBR_SCALE); -+ bbr->inflight_lo = -+ max_t(u32, bbr->inflight_latest, -+ (u64)bbr->inflight_lo * -+ (BBR_UNIT - beta) >> BBR_SCALE); -+ } -+ -+ /* Adjust to the lower of the levels implied by loss or ECN. */ -+ bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo); -+} -+ -+/* Reset any short-term lower-bound adaptation to congestion, so that we can -+ * push our inflight up. -+ */ -+static void bbr2_reset_lower_bounds(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->bw_lo = ~0U; -+ bbr->inflight_lo = ~0U; -+} -+ -+/* After bw probing (STARTUP/PROBE_UP), reset signals before entering a state -+ * machine phase where we adapt our lower bound based on congestion signals. -+ */ -+static void bbr2_reset_congestion_signals(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->loss_in_round = 0; -+ bbr->ecn_in_round = 0; -+ bbr->loss_in_cycle = 0; -+ bbr->ecn_in_cycle = 0; -+ bbr->bw_latest = 0; -+ bbr->inflight_latest = 0; -+} -+ -+/* Update (most of) our congestion signals: track the recent rate and volume of -+ * delivered data, presence of loss, and EWMA degree of ECN marking. -+ */ -+static void bbr2_update_congestion_signals( -+ struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ u64 bw; -+ -+ bbr->loss_round_start = 0; -+ if (rs->interval_us <= 0 || !rs->acked_sacked) -+ return; /* Not a valid observation */ -+ bw = ctx->sample_bw; -+ -+ if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) -+ bbr2_take_bw_hi_sample(sk, bw); -+ -+ bbr->loss_in_round |= (rs->losses > 0); -+ -+ /* Update rate and volume of delivered data from latest round trip: */ -+ bbr->bw_latest = max_t(u32, bbr->bw_latest, ctx->sample_bw); -+ bbr->inflight_latest = max_t(u32, bbr->inflight_latest, rs->delivered); -+ -+ if (before(rs->prior_delivered, bbr->loss_round_delivered)) -+ return; /* skip the per-round-trip updates */ -+ /* Now do per-round-trip updates. */ -+ bbr->loss_round_delivered = tp->delivered; /* mark round trip */ -+ bbr->loss_round_start = 1; -+ bbr2_adapt_lower_bounds(sk); -+ -+ /* Update windowed "latest" (single-round-trip) filters. */ -+ bbr->loss_in_round = 0; -+ bbr->ecn_in_round = 0; -+ bbr->bw_latest = ctx->sample_bw; -+ bbr->inflight_latest = rs->delivered; -+} -+ -+/* Bandwidth probing can cause loss. To help coexistence with loss-based -+ * congestion control we spread out our probing in a Reno-conscious way. Due to -+ * the shape of the Reno sawtooth, the time required between loss epochs for an -+ * idealized Reno flow is a number of round trips that is the BDP of that -+ * flow. We count packet-timed round trips directly, since measured RTT can -+ * vary widely, and Reno is driven by packet-timed round trips. -+ */ -+static bool bbr2_is_reno_coexistence_probe_time(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 inflight, rounds, reno_gain, reno_rounds; -+ -+ /* Random loss can shave some small percentage off of our inflight -+ * in each round. To survive this, flows need robust periodic probes. -+ */ -+ rounds = bbr->params.bw_probe_max_rounds; -+ -+ reno_gain = bbr->params.bw_probe_reno_gain; -+ if (reno_gain) { -+ inflight = bbr2_target_inflight(sk); -+ reno_rounds = ((u64)inflight * reno_gain) >> BBR_SCALE; -+ rounds = min(rounds, reno_rounds); -+ } -+ return bbr->rounds_since_probe >= rounds; -+} -+ -+/* How long do we want to wait before probing for bandwidth (and risking -+ * loss)? We randomize the wait, for better mixing and fairness convergence. -+ * -+ * We bound the Reno-coexistence inter-bw-probe time to be 62-63 round trips. -+ * This is calculated to allow fairness with a 25Mbps, 30ms Reno flow, -+ * (eg 4K video to a broadband user): -+ * BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets -+ * -+ * We bound the BBR-native inter-bw-probe wall clock time to be: -+ * (a) higher than 2 sec: to try to avoid causing loss for a long enough time -+ * to allow Reno at 30ms to get 4K video bw, the inter-bw-probe time must -+ * be at least: 25Mbps * .030sec / (1514bytes) * 0.030sec = 1.9secs -+ * (b) lower than 3 sec: to ensure flows can start probing in a reasonable -+ * amount of time to discover unutilized bw on human-scale interactive -+ * time-scales (e.g. perhaps traffic from a web page download that we -+ * were competing with is now complete). -+ */ -+static void bbr2_pick_probe_wait(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ /* Decide the random round-trip bound for wait until probe: */ -+ bbr->rounds_since_probe = -+ get_random_u32_below(bbr->params.bw_probe_rand_rounds); -+ /* Decide the random wall clock bound for wait until probe: */ -+ bbr->probe_wait_us = bbr->params.bw_probe_base_us + -+ get_random_u32_below(bbr->params.bw_probe_rand_us); -+} -+ -+static void bbr2_set_cycle_idx(struct sock *sk, int cycle_idx) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->cycle_idx = cycle_idx; -+ /* New phase, so need to update cwnd and pacing rate. */ -+ bbr->try_fast_path = 0; -+} -+ -+/* Send at estimated bw to fill the pipe, but not queue. We need this phase -+ * before PROBE_UP, because as soon as we send faster than the available bw -+ * we will start building a queue, and if the buffer is shallow we can cause -+ * loss. If we do not fill the pipe before we cause this loss, our bw_hi and -+ * inflight_hi estimates will underestimate. -+ */ -+static void bbr2_start_bw_probe_refill(struct sock *sk, u32 bw_probe_up_rounds) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr2_reset_lower_bounds(sk); -+ if (bbr->inflight_hi != ~0U) -+ bbr->inflight_hi += bbr->params.refill_add_inc; -+ bbr->bw_probe_up_rounds = bw_probe_up_rounds; -+ bbr->bw_probe_up_acks = 0; -+ bbr->stopped_risky_probe = 0; -+ bbr->ack_phase = BBR_ACKS_REFILLING; -+ bbr->next_rtt_delivered = tp->delivered; -+ bbr2_set_cycle_idx(sk, BBR_BW_PROBE_REFILL); -+} -+ -+/* Now probe max deliverable data rate and volume. */ -+static void bbr2_start_bw_probe_up(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->ack_phase = BBR_ACKS_PROBE_STARTING; -+ bbr->next_rtt_delivered = tp->delivered; -+ bbr->cycle_mstamp = tp->tcp_mstamp; -+ bbr2_set_cycle_idx(sk, BBR_BW_PROBE_UP); -+ bbr2_raise_inflight_hi_slope(sk); -+} -+ -+/* Start a new PROBE_BW probing cycle of some wall clock length. Pick a wall -+ * clock time at which to probe beyond an inflight that we think to be -+ * safe. This will knowingly risk packet loss, so we want to do this rarely, to -+ * keep packet loss rates low. Also start a round-trip counter, to probe faster -+ * if we estimate a Reno flow at our BDP would probe faster. -+ */ -+static void bbr2_start_bw_probe_down(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr2_reset_congestion_signals(sk); -+ bbr->bw_probe_up_cnt = ~0U; /* not growing inflight_hi any more */ -+ bbr2_pick_probe_wait(sk); -+ bbr->cycle_mstamp = tp->tcp_mstamp; /* start wall clock */ -+ bbr->ack_phase = BBR_ACKS_PROBE_STOPPING; -+ bbr->next_rtt_delivered = tp->delivered; -+ bbr2_set_cycle_idx(sk, BBR_BW_PROBE_DOWN); -+} -+ -+/* Cruise: maintain what we estimate to be a neutral, conservative -+ * operating point, without attempting to probe up for bandwidth or down for -+ * RTT, and only reducing inflight in response to loss/ECN signals. -+ */ -+static void bbr2_start_bw_probe_cruise(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (bbr->inflight_lo != ~0U) -+ bbr->inflight_lo = min(bbr->inflight_lo, bbr->inflight_hi); -+ -+ bbr2_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE); -+} -+ -+/* Loss and/or ECN rate is too high while probing. -+ * Adapt (once per bw probe) by cutting inflight_hi and then restarting cycle. -+ */ -+static void bbr2_handle_inflight_too_high(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ const u32 beta = bbr->params.beta; -+ -+ bbr->prev_probe_too_high = 1; -+ bbr->bw_probe_samples = 0; /* only react once per probe */ -+ bbr->debug.event = 'L'; /* Loss/ECN too high */ -+ /* If we are app-limited then we are not robustly -+ * probing the max volume of inflight data we think -+ * might be safe (analogous to how app-limited bw -+ * samples are not known to be robustly probing bw). -+ */ -+ if (!rs->is_app_limited) -+ bbr->inflight_hi = max_t(u32, rs->tx_in_flight, -+ (u64)bbr2_target_inflight(sk) * -+ (BBR_UNIT - beta) >> BBR_SCALE); -+ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) -+ bbr2_start_bw_probe_down(sk); -+} -+ -+/* If we're seeing bw and loss samples reflecting our bw probing, adapt -+ * using the signals we see. If loss or ECN mark rate gets too high, then adapt -+ * inflight_hi downward. If we're able to push inflight higher without such -+ * signals, push higher: adapt inflight_hi upward. -+ */ -+static bool bbr2_adapt_upper_bounds(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ /* Track when we'll see bw/loss samples resulting from our bw probes. */ -+ if (bbr->ack_phase == BBR_ACKS_PROBE_STARTING && bbr->round_start) -+ bbr->ack_phase = BBR_ACKS_PROBE_FEEDBACK; -+ if (bbr->ack_phase == BBR_ACKS_PROBE_STOPPING && bbr->round_start) { -+ /* End of samples from bw probing phase. */ -+ bbr->bw_probe_samples = 0; -+ bbr->ack_phase = BBR_ACKS_INIT; -+ /* At this point in the cycle, our current bw sample is also -+ * our best recent chance at finding the highest available bw -+ * for this flow. So now is the best time to forget the bw -+ * samples from the previous cycle, by advancing the window. -+ */ -+ if (bbr->mode == BBR_PROBE_BW && !rs->is_app_limited) -+ bbr2_advance_bw_hi_filter(sk); -+ /* If we had an inflight_hi, then probed and pushed inflight all -+ * the way up to hit that inflight_hi without seeing any -+ * high loss/ECN in all the resulting ACKs from that probing, -+ * then probe up again, this time letting inflight persist at -+ * inflight_hi for a round trip, then accelerating beyond. -+ */ -+ if (bbr->mode == BBR_PROBE_BW && -+ bbr->stopped_risky_probe && !bbr->prev_probe_too_high) { -+ bbr->debug.event = 'R'; /* reprobe */ -+ bbr2_start_bw_probe_refill(sk, 0); -+ return true; /* yes, decided state transition */ -+ } -+ } -+ -+ if (bbr2_is_inflight_too_high(sk, rs)) { -+ if (bbr->bw_probe_samples) /* sample is from bw probing? */ -+ bbr2_handle_inflight_too_high(sk, rs); -+ } else { -+ /* Loss/ECN rate is declared safe. Adjust upper bound upward. */ -+ if (bbr->inflight_hi == ~0U) /* no excess queue signals yet? */ -+ return false; -+ -+ /* To be resilient to random loss, we must raise inflight_hi -+ * if we observe in any phase that a higher level is safe. -+ */ -+ if (rs->tx_in_flight > bbr->inflight_hi) { -+ bbr->inflight_hi = rs->tx_in_flight; -+ bbr->debug.event = 'U'; /* raise up inflight_hi */ -+ } -+ -+ if (bbr->mode == BBR_PROBE_BW && -+ bbr->cycle_idx == BBR_BW_PROBE_UP) -+ bbr2_probe_inflight_hi_upward(sk, rs); -+ } -+ -+ return false; -+} -+ -+/* Check if it's time to probe for bandwidth now, and if so, kick it off. */ -+static bool bbr2_check_time_to_probe_bw(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 n; -+ -+ /* If we seem to be at an operating point where we are not seeing loss -+ * but we are seeing ECN marks, then when the ECN marks cease we reprobe -+ * quickly (in case a burst of cross-traffic has ceased and freed up bw, -+ * or in case we are sharing with multiplicatively probing traffic). -+ */ -+ if (bbr->params.ecn_reprobe_gain && bbr->ecn_eligible && -+ bbr->ecn_in_cycle && !bbr->loss_in_cycle && -+ inet_csk(sk)->icsk_ca_state == TCP_CA_Open) { -+ bbr->debug.event = 'A'; /* *A*ll clear to probe *A*gain */ -+ /* Calculate n so that when bbr2_raise_inflight_hi_slope() -+ * computes growth_this_round as 2^n it will be roughly the -+ * desired volume of data (inflight_hi*ecn_reprobe_gain). -+ */ -+ n = ilog2((((u64)bbr->inflight_hi * -+ bbr->params.ecn_reprobe_gain) >> BBR_SCALE)); -+ bbr2_start_bw_probe_refill(sk, n); -+ return true; -+ } -+ -+ if (bbr2_has_elapsed_in_phase(sk, bbr->probe_wait_us) || -+ bbr2_is_reno_coexistence_probe_time(sk)) { -+ bbr2_start_bw_probe_refill(sk, 0); -+ return true; -+ } -+ return false; -+} -+ -+/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */ -+static bool bbr2_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ bool is_under_bdp, is_long_enough; -+ -+ /* Always need to pull inflight down to leave headroom in queue. */ -+ if (inflight > bbr2_inflight_with_headroom(sk)) -+ return false; -+ -+ is_under_bdp = inflight <= bbr_inflight(sk, bw, BBR_UNIT); -+ if (bbr->params.drain_to_target) -+ return is_under_bdp; -+ -+ is_long_enough = bbr2_has_elapsed_in_phase(sk, bbr->min_rtt_us); -+ return is_under_bdp || is_long_enough; -+} -+ -+/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */ -+static void bbr2_update_cycle_phase(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ bool is_risky = false, is_queuing = false; -+ u32 inflight, bw; -+ -+ if (!bbr_full_bw_reached(sk)) -+ return; -+ -+ /* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */ -+ if (bbr2_adapt_upper_bounds(sk, rs)) -+ return; /* already decided state transition */ -+ -+ if (bbr->mode != BBR_PROBE_BW) -+ return; -+ -+ inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight); -+ bw = bbr_max_bw(sk); -+ -+ switch (bbr->cycle_idx) { -+ /* First we spend most of our time cruising with a pacing_gain of 1.0, -+ * which paces at the estimated bw, to try to fully use the pipe -+ * without building queue. If we encounter loss/ECN marks, we adapt -+ * by slowing down. -+ */ -+ case BBR_BW_PROBE_CRUISE: -+ if (bbr2_check_time_to_probe_bw(sk)) -+ return; /* already decided state transition */ -+ break; -+ -+ /* After cruising, when it's time to probe, we first "refill": we send -+ * at the estimated bw to fill the pipe, before probing higher and -+ * knowingly risking overflowing the bottleneck buffer (causing loss). -+ */ -+ case BBR_BW_PROBE_REFILL: -+ if (bbr->round_start) { -+ /* After one full round trip of sending in REFILL, we -+ * start to see bw samples reflecting our REFILL, which -+ * may be putting too much data in flight. -+ */ -+ bbr->bw_probe_samples = 1; -+ bbr2_start_bw_probe_up(sk); -+ } -+ break; -+ -+ /* After we refill the pipe, we probe by using a pacing_gain > 1.0, to -+ * probe for bw. If we have not seen loss/ECN, we try to raise inflight -+ * to at least pacing_gain*BDP; note that this may take more than -+ * min_rtt if min_rtt is small (e.g. on a LAN). -+ * -+ * We terminate PROBE_UP bandwidth probing upon any of the following: -+ * -+ * (1) We've pushed inflight up to hit the inflight_hi target set in the -+ * most recent previous bw probe phase. Thus we want to start -+ * draining the queue immediately because it's very likely the most -+ * recently sent packets will fill the queue and cause drops. -+ * (checked here) -+ * (2) We have probed for at least 1*min_rtt_us, and the -+ * estimated queue is high enough (inflight > 1.25 * estimated_bdp). -+ * (checked here) -+ * (3) Loss filter says loss rate is "too high". -+ * (checked in bbr_is_inflight_too_high()) -+ * (4) ECN filter says ECN mark rate is "too high". -+ * (checked in bbr_is_inflight_too_high()) -+ */ -+ case BBR_BW_PROBE_UP: -+ if (bbr->prev_probe_too_high && -+ inflight >= bbr->inflight_hi) { -+ bbr->stopped_risky_probe = 1; -+ is_risky = true; -+ bbr->debug.event = 'D'; /* D for danger */ -+ } else if (bbr2_has_elapsed_in_phase(sk, bbr->min_rtt_us) && -+ inflight >= -+ bbr_inflight(sk, bw, -+ bbr->params.bw_probe_pif_gain)) { -+ is_queuing = true; -+ bbr->debug.event = 'Q'; /* building Queue */ -+ } -+ if (is_risky || is_queuing) { -+ bbr->prev_probe_too_high = 0; /* no loss/ECN (yet) */ -+ bbr2_start_bw_probe_down(sk); /* restart w/ down */ -+ } -+ break; -+ -+ /* After probing in PROBE_UP, we have usually accumulated some data in -+ * the bottleneck buffer (if bw probing didn't find more bw). We next -+ * enter PROBE_DOWN to try to drain any excess data from the queue. To -+ * do this, we use a pacing_gain < 1.0. We hold this pacing gain until -+ * our inflight is less then that target cruising point, which is the -+ * minimum of (a) the amount needed to leave headroom, and (b) the -+ * estimated BDP. Once inflight falls to match the target, we estimate -+ * the queue is drained; persisting would underutilize the pipe. -+ */ -+ case BBR_BW_PROBE_DOWN: -+ if (bbr2_check_time_to_probe_bw(sk)) -+ return; /* already decided state transition */ -+ if (bbr2_check_time_to_cruise(sk, inflight, bw)) -+ bbr2_start_bw_probe_cruise(sk); -+ break; -+ -+ default: -+ WARN_ONCE(1, "BBR invalid cycle index %u\n", bbr->cycle_idx); -+ } -+} -+ -+/* Exiting PROBE_RTT, so return to bandwidth probing in STARTUP or PROBE_BW. */ -+static void bbr2_exit_probe_rtt(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr2_reset_lower_bounds(sk); -+ if (bbr_full_bw_reached(sk)) { -+ bbr->mode = BBR_PROBE_BW; -+ /* Raising inflight after PROBE_RTT may cause loss, so reset -+ * the PROBE_BW clock and schedule the next bandwidth probe for -+ * a friendly and randomized future point in time. -+ */ -+ bbr2_start_bw_probe_down(sk); -+ /* Since we are exiting PROBE_RTT, we know inflight is -+ * below our estimated BDP, so it is reasonable to cruise. -+ */ -+ bbr2_start_bw_probe_cruise(sk); -+ } else { -+ bbr->mode = BBR_STARTUP; -+ } -+} -+ -+/* Exit STARTUP based on loss rate > 1% and loss gaps in round >= N. Wait until -+ * the end of the round in recovery to get a good estimate of how many packets -+ * have been lost, and how many we need to drain with a low pacing rate. -+ */ -+static void bbr2_check_loss_too_high_in_startup(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (bbr_full_bw_reached(sk)) -+ return; -+ -+ /* For STARTUP exit, check the loss rate at the end of each round trip -+ * of Recovery episodes in STARTUP. We check the loss rate at the end -+ * of the round trip to filter out noisy/low loss and have a better -+ * sense of inflight (extent of loss), so we can drain more accurately. -+ */ -+ if (rs->losses && bbr->loss_events_in_round < 0xf) -+ bbr->loss_events_in_round++; /* update saturating counter */ -+ if (bbr->params.full_loss_cnt && bbr->loss_round_start && -+ inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery && -+ bbr->loss_events_in_round >= bbr->params.full_loss_cnt && -+ bbr2_is_inflight_too_high(sk, rs)) { -+ bbr->debug.event = 'P'; /* Packet loss caused STARTUP exit */ -+ bbr2_handle_queue_too_high_in_startup(sk); -+ return; -+ } -+ if (bbr->loss_round_start) -+ bbr->loss_events_in_round = 0; -+} -+ -+/* If we are done draining, advance into steady state operation in PROBE_BW. */ -+static void bbr2_check_drain(struct sock *sk, const struct rate_sample *rs, -+ struct bbr_context *ctx) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (bbr_check_drain(sk, rs, ctx)) { -+ bbr->mode = BBR_PROBE_BW; -+ bbr2_start_bw_probe_down(sk); -+ } -+} -+ -+static void bbr2_update_model(struct sock *sk, const struct rate_sample *rs, -+ struct bbr_context *ctx) -+{ -+ bbr2_update_congestion_signals(sk, rs, ctx); -+ bbr_update_ack_aggregation(sk, rs); -+ bbr2_check_loss_too_high_in_startup(sk, rs); -+ bbr_check_full_bw_reached(sk, rs); -+ bbr2_check_drain(sk, rs, ctx); -+ bbr2_update_cycle_phase(sk, rs); -+ bbr_update_min_rtt(sk, rs); -+} -+ -+/* Fast path for app-limited case. -+ * -+ * On each ack, we execute bbr state machine, which primarily consists of: -+ * 1) update model based on new rate sample, and -+ * 2) update control based on updated model or state change. -+ * -+ * There are certain workload/scenarios, e.g. app-limited case, where -+ * either we can skip updating model or we can skip update of both model -+ * as well as control. This provides signifcant softirq cpu savings for -+ * processing incoming acks. -+ * -+ * In case of app-limited, if there is no congestion (loss/ecn) and -+ * if observed bw sample is less than current estimated bw, then we can -+ * skip some of the computation in bbr state processing: -+ * -+ * - if there is no rtt/mode/phase change: In this case, since all the -+ * parameters of the network model are constant, we can skip model -+ * as well control update. -+ * -+ * - else we can skip rest of the model update. But we still need to -+ * update the control to account for the new rtt/mode/phase. -+ * -+ * Returns whether we can take fast path or not. -+ */ -+static bool bbr2_fast_path(struct sock *sk, bool *update_model, -+ const struct rate_sample *rs, struct bbr_context *ctx) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 prev_min_rtt_us, prev_mode; -+ -+ if (bbr->params.fast_path && bbr->try_fast_path && -+ rs->is_app_limited && ctx->sample_bw < bbr_max_bw(sk) && -+ !bbr->loss_in_round && !bbr->ecn_in_round) { -+ prev_mode = bbr->mode; -+ prev_min_rtt_us = bbr->min_rtt_us; -+ bbr2_check_drain(sk, rs, ctx); -+ bbr2_update_cycle_phase(sk, rs); -+ bbr_update_min_rtt(sk, rs); -+ -+ if (bbr->mode == prev_mode && -+ bbr->min_rtt_us == prev_min_rtt_us && -+ bbr->try_fast_path) -+ return true; -+ -+ /* Skip model update, but control still needs to be updated */ -+ *update_model = false; -+ } -+ return false; -+} -+ -+static void bbr2_main(struct sock *sk, const struct rate_sample *rs) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ struct bbr_context ctx = { 0 }; -+ bool update_model = true; -+ u32 bw; -+ -+ bbr->debug.event = '.'; /* init to default NOP (no event yet) */ -+ -+ bbr_update_round_start(sk, rs, &ctx); -+ if (bbr->round_start) { -+ bbr->rounds_since_probe = -+ min_t(s32, bbr->rounds_since_probe + 1, 0xFF); -+ bbr2_update_ecn_alpha(sk); -+ } -+ -+ bbr->ecn_in_round |= rs->is_ece; -+ bbr_calculate_bw_sample(sk, rs, &ctx); -+ -+ if (bbr2_fast_path(sk, &update_model, rs, &ctx)) -+ goto out; -+ -+ if (update_model) -+ bbr2_update_model(sk, rs, &ctx); -+ -+ bbr_update_gains(sk); -+ bw = bbr_bw(sk); -+ bbr_set_pacing_rate(sk, bw, bbr->pacing_gain); -+ bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain, -+ tp->snd_cwnd, &ctx); -+ bbr2_bound_cwnd_for_inflight_model(sk); -+ -+out: -+ bbr->prev_ca_state = inet_csk(sk)->icsk_ca_state; -+ bbr->loss_in_cycle |= rs->lost > 0; -+ bbr->ecn_in_cycle |= rs->delivered_ce > 0; -+ -+ bbr_debug(sk, rs->acked_sacked, rs, &ctx); -+} -+ -+/* Module parameters that are settable by TCP_CONGESTION_PARAMS are declared -+ * down here, so that the algorithm functions that use the parameters must use -+ * the per-socket parameters; if they accidentally use the global version -+ * then there will be a compile error. -+ * TODO(ncardwell): move all per-socket parameters down to this section. -+ */ -+ -+/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE. -+ * No loss response when 0. Max allwed value is 255. -+ */ -+static u32 bbr_beta = BBR_UNIT * 30 / 100; -+ -+/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE. -+ * Max allowed value is 255. -+ */ -+static u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16; /* 1/16 = 6.25% */ -+ -+/* The initial value for the ecn_alpha state variable. Default and max -+ * BBR_UNIT (256), representing 1.0. This allows a flow to respond quickly -+ * to congestion if the bottleneck is congested when the flow starts up. -+ */ -+static u32 bbr_ecn_alpha_init = BBR_UNIT; /* 1.0, to respond quickly */ -+ -+/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE. -+ * No ECN based bounding when 0. Max allwed value is 255. -+ */ -+static u32 bbr_ecn_factor = BBR_UNIT * 1 / 3; /* 1/3 = 33% */ -+ -+/* Estimate bw probing has gone too far if CE ratio exceeds this threshold. -+ * Scaled by BBR_SCALE. Disabled when 0. Max allowed is 255. -+ */ -+static u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2; /* 1/2 = 50% */ -+ -+/* Max RTT (in usec) at which to use sender-side ECN logic. -+ * Disabled when 0 (ECN allowed at any RTT). -+ * Max allowed for the parameter is 524287 (0x7ffff) us, ~524 ms. -+ */ -+static u32 bbr_ecn_max_rtt_us = 5000; -+ -+/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN -+ * clears then use a multiplicative increase to quickly reprobe bw by -+ * starting inflight probing at the given multiple of inflight_hi. -+ * Default for this experimental knob is 0 (disabled). -+ * Planned value for experiments: BBR_UNIT * 1 / 2 = 128, representing 0.5. -+ */ -+static u32 bbr_ecn_reprobe_gain; -+ -+/* Estimate bw probing has gone too far if loss rate exceeds this level. */ -+static u32 bbr_loss_thresh = BBR_UNIT * 2 / 100; /* 2% loss */ -+ -+/* Exit STARTUP if number of loss marking events in a Recovery round is >= N, -+ * and loss rate is higher than bbr_loss_thresh. -+ * Disabled if 0. Max allowed value is 15 (0xF). -+ */ -+static u32 bbr_full_loss_cnt = 8; -+ -+/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh -+ * meets this count. Max allowed value is 3. -+ */ -+static u32 bbr_full_ecn_cnt = 2; -+ -+/* Fraction of unutilized headroom to try to leave in path upon high loss. */ -+static u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100; -+ -+/* Multiplier to get target inflight (as multiple of BDP) for PROBE_UP phase. -+ * Default is 1.25x, as in BBR v1. Max allowed is 511. -+ */ -+static u32 bbr_bw_probe_pif_gain = BBR_UNIT * 5 / 4; -+ -+/* Multiplier to get Reno-style probe epoch duration as: k * BDP round trips. -+ * If zero, disables this BBR v2 Reno-style BDP-scaled coexistence mechanism. -+ * Max allowed is 511. -+ */ -+static u32 bbr_bw_probe_reno_gain = BBR_UNIT; -+ -+/* Max number of packet-timed rounds to wait before probing for bandwidth. If -+ * we want to tolerate 1% random loss per round, and not have this cut our -+ * inflight too much, we must probe for bw periodically on roughly this scale. -+ * If low, limits Reno/CUBIC coexistence; if high, limits loss tolerance. -+ * We aim to be fair with Reno/CUBIC up to a BDP of at least: -+ * BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets -+ */ -+static u32 bbr_bw_probe_max_rounds = 63; -+ -+/* Max amount of randomness to inject in round counting for Reno-coexistence. -+ * Max value is 15. -+ */ -+static u32 bbr_bw_probe_rand_rounds = 2; -+ -+/* Use BBR-native probe time scale starting at this many usec. -+ * We aim to be fair with Reno/CUBIC up to an inter-loss time epoch of at least: -+ * BDP*RTT = 25Mbps * .030sec /(1514bytes) * 0.030sec = 1.9 secs -+ */ -+static u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC; /* 2 secs */ -+ -+/* Use BBR-native probes spread over this many usec: */ -+static u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC; /* 1 secs */ -+ -+/* Undo the model changes made in loss recovery if recovery was spurious? */ -+static bool bbr_undo = true; -+ -+/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */ -+static bool bbr_fast_path = true; /* default: enabled */ -+ -+/* Use fast ack mode ? */ -+static int bbr_fast_ack_mode = 1; /* default: rwnd check off */ -+ -+/* How much to additively increase inflight_hi when entering REFILL? */ -+static u32 bbr_refill_add_inc; /* default: disabled */ -+ -+module_param_named(beta, bbr_beta, uint, 0644); -+module_param_named(ecn_alpha_gain, bbr_ecn_alpha_gain, uint, 0644); -+module_param_named(ecn_alpha_init, bbr_ecn_alpha_init, uint, 0644); -+module_param_named(ecn_factor, bbr_ecn_factor, uint, 0644); -+module_param_named(ecn_thresh, bbr_ecn_thresh, uint, 0644); -+module_param_named(ecn_max_rtt_us, bbr_ecn_max_rtt_us, uint, 0644); -+module_param_named(ecn_reprobe_gain, bbr_ecn_reprobe_gain, uint, 0644); -+module_param_named(loss_thresh, bbr_loss_thresh, uint, 0664); -+module_param_named(full_loss_cnt, bbr_full_loss_cnt, uint, 0664); -+module_param_named(full_ecn_cnt, bbr_full_ecn_cnt, uint, 0664); -+module_param_named(inflight_headroom, bbr_inflight_headroom, uint, 0664); -+module_param_named(bw_probe_pif_gain, bbr_bw_probe_pif_gain, uint, 0664); -+module_param_named(bw_probe_reno_gain, bbr_bw_probe_reno_gain, uint, 0664); -+module_param_named(bw_probe_max_rounds, bbr_bw_probe_max_rounds, uint, 0664); -+module_param_named(bw_probe_rand_rounds, bbr_bw_probe_rand_rounds, uint, 0664); -+module_param_named(bw_probe_base_us, bbr_bw_probe_base_us, uint, 0664); -+module_param_named(bw_probe_rand_us, bbr_bw_probe_rand_us, uint, 0664); -+module_param_named(undo, bbr_undo, bool, 0664); -+module_param_named(fast_path, bbr_fast_path, bool, 0664); -+module_param_named(fast_ack_mode, bbr_fast_ack_mode, uint, 0664); -+module_param_named(refill_add_inc, bbr_refill_add_inc, uint, 0664); -+ -+static void bbr2_init(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr_init(sk); /* run shared init code for v1 and v2 */ -+ -+ /* BBR v2 parameters: */ -+ bbr->params.beta = min_t(u32, 0xFFU, bbr_beta); -+ bbr->params.ecn_alpha_gain = min_t(u32, 0xFFU, bbr_ecn_alpha_gain); -+ bbr->params.ecn_alpha_init = min_t(u32, BBR_UNIT, bbr_ecn_alpha_init); -+ bbr->params.ecn_factor = min_t(u32, 0xFFU, bbr_ecn_factor); -+ bbr->params.ecn_thresh = min_t(u32, 0xFFU, bbr_ecn_thresh); -+ bbr->params.ecn_max_rtt_us = min_t(u32, 0x7ffffU, bbr_ecn_max_rtt_us); -+ bbr->params.ecn_reprobe_gain = min_t(u32, 0x1FF, bbr_ecn_reprobe_gain); -+ bbr->params.loss_thresh = min_t(u32, 0xFFU, bbr_loss_thresh); -+ bbr->params.full_loss_cnt = min_t(u32, 0xFU, bbr_full_loss_cnt); -+ bbr->params.full_ecn_cnt = min_t(u32, 0x3U, bbr_full_ecn_cnt); -+ bbr->params.inflight_headroom = -+ min_t(u32, 0xFFU, bbr_inflight_headroom); -+ bbr->params.bw_probe_pif_gain = -+ min_t(u32, 0x1FFU, bbr_bw_probe_pif_gain); -+ bbr->params.bw_probe_reno_gain = -+ min_t(u32, 0x1FFU, bbr_bw_probe_reno_gain); -+ bbr->params.bw_probe_max_rounds = -+ min_t(u32, 0xFFU, bbr_bw_probe_max_rounds); -+ bbr->params.bw_probe_rand_rounds = -+ min_t(u32, 0xFU, bbr_bw_probe_rand_rounds); -+ bbr->params.bw_probe_base_us = -+ min_t(u32, (1 << 26) - 1, bbr_bw_probe_base_us); -+ bbr->params.bw_probe_rand_us = -+ min_t(u32, (1 << 26) - 1, bbr_bw_probe_rand_us); -+ bbr->params.undo = bbr_undo; -+ bbr->params.fast_path = bbr_fast_path ? 1 : 0; -+ bbr->params.refill_add_inc = min_t(u32, 0x3U, bbr_refill_add_inc); -+ -+ /* BBR v2 state: */ -+ bbr->initialized = 1; -+ /* Start sampling ECN mark rate after first full flight is ACKed: */ -+ bbr->loss_round_delivered = tp->delivered + 1; -+ bbr->loss_round_start = 0; -+ bbr->undo_bw_lo = 0; -+ bbr->undo_inflight_lo = 0; -+ bbr->undo_inflight_hi = 0; -+ bbr->loss_events_in_round = 0; -+ bbr->startup_ecn_rounds = 0; -+ bbr2_reset_congestion_signals(sk); -+ bbr->bw_lo = ~0U; -+ bbr->bw_hi[0] = 0; -+ bbr->bw_hi[1] = 0; -+ bbr->inflight_lo = ~0U; -+ bbr->inflight_hi = ~0U; -+ bbr->bw_probe_up_cnt = ~0U; -+ bbr->bw_probe_up_acks = 0; -+ bbr->bw_probe_up_rounds = 0; -+ bbr->probe_wait_us = 0; -+ bbr->stopped_risky_probe = 0; -+ bbr->ack_phase = BBR_ACKS_INIT; -+ bbr->rounds_since_probe = 0; -+ bbr->bw_probe_samples = 0; -+ bbr->prev_probe_too_high = 0; -+ bbr->ecn_eligible = 0; -+ bbr->ecn_alpha = bbr->params.ecn_alpha_init; -+ bbr->alpha_last_delivered = 0; -+ bbr->alpha_last_delivered_ce = 0; -+ -+ tp->fast_ack_mode = min_t(u32, 0x2U, bbr_fast_ack_mode); -+ -+ if ((tp->ecn_flags & TCP_ECN_OK) && bbr_ecn_enable) -+ tp->ecn_flags |= TCP_ECN_ECT_PERMANENT; -+} -+ -+/* Core TCP stack informs us that the given skb was just marked lost. */ -+static void bbr2_skb_marked_lost(struct sock *sk, const struct sk_buff *skb) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ struct tcp_skb_cb *scb = TCP_SKB_CB(skb); -+ struct rate_sample rs; -+ -+ /* Capture "current" data over the full round trip of loss, -+ * to have a better chance to see the full capacity of the path. -+ */ -+ if (!bbr->loss_in_round) /* first loss in this round trip? */ -+ bbr->loss_round_delivered = tp->delivered; /* set round trip */ -+ bbr->loss_in_round = 1; -+ bbr->loss_in_cycle = 1; -+ -+ if (!bbr->bw_probe_samples) -+ return; /* not an skb sent while probing for bandwidth */ -+ if (unlikely(!scb->tx.delivered_mstamp)) -+ return; /* skb was SACKed, reneged, marked lost; ignore it */ -+ /* We are probing for bandwidth. Construct a rate sample that -+ * estimates what happened in the flight leading up to this lost skb, -+ * then see if the loss rate went too high, and if so at which packet. -+ */ -+ memset(&rs, 0, sizeof(rs)); -+ rs.tx_in_flight = scb->tx.in_flight; -+ rs.lost = tp->lost - scb->tx.lost; -+ rs.is_app_limited = scb->tx.is_app_limited; -+ if (bbr2_is_inflight_too_high(sk, &rs)) { -+ rs.tx_in_flight = bbr2_inflight_hi_from_lost_skb(sk, &rs, skb); -+ bbr2_handle_inflight_too_high(sk, &rs); -+ } -+} -+ -+/* Revert short-term model if current loss recovery event was spurious. */ -+static u32 bbr2_undo_cwnd(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->debug.undo = 1; -+ bbr->full_bw = 0; /* spurious slow-down; reset full pipe detection */ -+ bbr->full_bw_cnt = 0; -+ bbr->loss_in_round = 0; -+ -+ if (!bbr->params.undo) -+ return tp->snd_cwnd; -+ -+ /* Revert to cwnd and other state saved before loss episode. */ -+ bbr->bw_lo = max(bbr->bw_lo, bbr->undo_bw_lo); -+ bbr->inflight_lo = max(bbr->inflight_lo, bbr->undo_inflight_lo); -+ bbr->inflight_hi = max(bbr->inflight_hi, bbr->undo_inflight_hi); -+ return bbr->prior_cwnd; -+} -+ -+/* Entering loss recovery, so save state for when we undo recovery. */ -+static u32 bbr2_ssthresh(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr_save_cwnd(sk); -+ /* For undo, save state that adapts based on loss signal. */ -+ bbr->undo_bw_lo = bbr->bw_lo; -+ bbr->undo_inflight_lo = bbr->inflight_lo; -+ bbr->undo_inflight_hi = bbr->inflight_hi; -+ return tcp_sk(sk)->snd_ssthresh; -+} -+ -+static enum tcp_bbr2_phase bbr2_get_phase(struct bbr *bbr) -+{ -+ switch (bbr->mode) { -+ case BBR_STARTUP: -+ return BBR2_PHASE_STARTUP; -+ case BBR_DRAIN: -+ return BBR2_PHASE_DRAIN; -+ case BBR_PROBE_BW: -+ break; -+ case BBR_PROBE_RTT: -+ return BBR2_PHASE_PROBE_RTT; -+ default: -+ return BBR2_PHASE_INVALID; -+ } -+ switch (bbr->cycle_idx) { -+ case BBR_BW_PROBE_UP: -+ return BBR2_PHASE_PROBE_BW_UP; -+ case BBR_BW_PROBE_DOWN: -+ return BBR2_PHASE_PROBE_BW_DOWN; -+ case BBR_BW_PROBE_CRUISE: -+ return BBR2_PHASE_PROBE_BW_CRUISE; -+ case BBR_BW_PROBE_REFILL: -+ return BBR2_PHASE_PROBE_BW_REFILL; -+ default: -+ return BBR2_PHASE_INVALID; -+ } -+} -+ -+static size_t bbr2_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 bbr *bbr = inet_csk_ca(sk); -+ u64 bw = bbr_bw_bytes_per_sec(sk, bbr_bw(sk)); -+ u64 bw_hi = bbr_bw_bytes_per_sec(sk, bbr_max_bw(sk)); -+ u64 bw_lo = bbr->bw_lo == ~0U ? -+ ~0ULL : bbr_bw_bytes_per_sec(sk, bbr->bw_lo); -+ -+ memset(&info->bbr2, 0, sizeof(info->bbr2)); -+ info->bbr2.bbr_bw_lsb = (u32)bw; -+ info->bbr2.bbr_bw_msb = (u32)(bw >> 32); -+ info->bbr2.bbr_min_rtt = bbr->min_rtt_us; -+ info->bbr2.bbr_pacing_gain = bbr->pacing_gain; -+ info->bbr2.bbr_cwnd_gain = bbr->cwnd_gain; -+ info->bbr2.bbr_bw_hi_lsb = (u32)bw_hi; -+ info->bbr2.bbr_bw_hi_msb = (u32)(bw_hi >> 32); -+ info->bbr2.bbr_bw_lo_lsb = (u32)bw_lo; -+ info->bbr2.bbr_bw_lo_msb = (u32)(bw_lo >> 32); -+ info->bbr2.bbr_mode = bbr->mode; -+ info->bbr2.bbr_phase = (__u8)bbr2_get_phase(bbr); -+ info->bbr2.bbr_version = (__u8)2; -+ info->bbr2.bbr_inflight_lo = bbr->inflight_lo; -+ info->bbr2.bbr_inflight_hi = bbr->inflight_hi; -+ info->bbr2.bbr_extra_acked = bbr_extra_acked(sk); -+ *attr = INET_DIAG_BBRINFO; -+ return sizeof(info->bbr2); -+ } -+ return 0; -+} -+ -+static void bbr2_set_state(struct sock *sk, u8 new_state) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (new_state == TCP_CA_Loss) { -+ struct rate_sample rs = { .losses = 1 }; -+ struct bbr_context ctx = { 0 }; -+ -+ bbr->prev_ca_state = TCP_CA_Loss; -+ bbr->full_bw = 0; -+ if (!bbr2_is_probing_bandwidth(sk) && bbr->inflight_lo == ~0U) { -+ /* bbr_adapt_lower_bounds() needs cwnd before -+ * we suffered an RTO, to update inflight_lo: -+ */ -+ bbr->inflight_lo = -+ max(tp->snd_cwnd, bbr->prior_cwnd); -+ } -+ bbr_debug(sk, 0, &rs, &ctx); -+ } else if (bbr->prev_ca_state == TCP_CA_Loss && -+ new_state != TCP_CA_Loss) { -+ tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd); -+ bbr->try_fast_path = 0; /* bound cwnd using latest model */ -+ } -+} -+ -+static struct tcp_congestion_ops tcp_bbr2_cong_ops __read_mostly = { -+ .flags = TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS, -+ .name = "bbr2", -+ .owner = THIS_MODULE, -+ .init = bbr2_init, -+ .cong_control = bbr2_main, -+ .sndbuf_expand = bbr_sndbuf_expand, -+ .skb_marked_lost = bbr2_skb_marked_lost, -+ .undo_cwnd = bbr2_undo_cwnd, -+ .cwnd_event = bbr_cwnd_event, -+ .ssthresh = bbr2_ssthresh, -+ .tso_segs = bbr_tso_segs, -+ .get_info = bbr2_get_info, -+ .set_state = bbr2_set_state, -+}; -+ -+static int __init bbr_register(void) -+{ -+ BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE); -+ return tcp_register_congestion_control(&tcp_bbr2_cong_ops); -+} -+ -+static void __exit bbr_unregister(void) -+{ -+ tcp_unregister_congestion_control(&tcp_bbr2_cong_ops); -+} -+ -+module_init(bbr_register); -+module_exit(bbr_unregister); -+ -+MODULE_AUTHOR("Van Jacobson <vanj@google.com>"); -+MODULE_AUTHOR("Neal Cardwell <ncardwell@google.com>"); -+MODULE_AUTHOR("Yuchung Cheng <ycheng@google.com>"); -+MODULE_AUTHOR("Soheil Hassas Yeganeh <soheil@google.com>"); -+MODULE_AUTHOR("Priyaranjan Jha <priyarjha@google.com>"); -+MODULE_AUTHOR("Yousuk Seung <ysseung@google.com>"); -+MODULE_AUTHOR("Kevin Yang <yyd@google.com>"); -+MODULE_AUTHOR("Arjun Roy <arjunroy@google.com>"); -+ -+MODULE_LICENSE("Dual BSD/GPL"); -+MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)"); -diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c -index d3cae40749e8..0f268f2ff2e9 100644 ---- a/net/ipv4/tcp_cong.c -+++ b/net/ipv4/tcp_cong.c -@@ -189,6 +189,7 @@ void tcp_init_congestion_control(struct sock *sk) - struct inet_connection_sock *icsk = inet_csk(sk); - - tcp_sk(sk)->prior_ssthresh = 0; -+ tcp_sk(sk)->fast_ack_mode = 0; - if (icsk->icsk_ca_ops->init) - icsk->icsk_ca_ops->init(sk); - if (tcp_ca_needs_ecn(sk)) -diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c -index 0640453fce54..8a455eb0c552 100644 ---- a/net/ipv4/tcp_input.c -+++ b/net/ipv4/tcp_input.c -@@ -349,7 +349,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) - tcp_enter_quickack_mode(sk, 2); - break; - case INET_ECN_CE: -- if (tcp_ca_needs_ecn(sk)) -+ if (tcp_ca_wants_ce_events(sk)) - tcp_ca_event(sk, CA_EVENT_ECN_IS_CE); - - if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) { -@@ -360,7 +360,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) - tp->ecn_flags |= TCP_ECN_SEEN; - break; - default: -- if (tcp_ca_needs_ecn(sk)) -+ if (tcp_ca_wants_ce_events(sk)) - tcp_ca_event(sk, CA_EVENT_ECN_NO_CE); - tp->ecn_flags |= TCP_ECN_SEEN; - break; -@@ -1079,7 +1079,12 @@ static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb) - */ - static void tcp_notify_skb_loss_event(struct tcp_sock *tp, const struct sk_buff *skb) - { -+ struct sock *sk = (struct sock *)tp; -+ const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; -+ - tp->lost += tcp_skb_pcount(skb); -+ if (ca_ops->skb_marked_lost) -+ ca_ops->skb_marked_lost(sk, skb); - } - - void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb) -@@ -1460,6 +1465,17 @@ static bool tcp_shifted_skb(struct sock *sk, struct sk_buff *prev, - WARN_ON_ONCE(tcp_skb_pcount(skb) < pcount); - tcp_skb_pcount_add(skb, -pcount); - -+ /* Adjust tx.in_flight as pcount is shifted from skb to prev. */ -+ if (WARN_ONCE(TCP_SKB_CB(skb)->tx.in_flight < pcount, -+ "prev in_flight: %u skb in_flight: %u pcount: %u", -+ TCP_SKB_CB(prev)->tx.in_flight, -+ TCP_SKB_CB(skb)->tx.in_flight, -+ pcount)) -+ TCP_SKB_CB(skb)->tx.in_flight = 0; -+ else -+ TCP_SKB_CB(skb)->tx.in_flight -= pcount; -+ TCP_SKB_CB(prev)->tx.in_flight += pcount; -+ - /* When we're adding to gso_segs == 1, gso_size will be zero, - * in theory this shouldn't be necessary but as long as DSACK - * code can come after this skb later on it's better to keep -@@ -3812,6 +3828,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) - - prior_fack = tcp_is_sack(tp) ? tcp_highest_sack_seq(tp) : tp->snd_una; - rs.prior_in_flight = tcp_packets_in_flight(tp); -+ tcp_rate_check_app_limited(sk); - - /* ts_recent update must be made after we are sure that the packet - * is in window. -@@ -3910,6 +3927,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) - delivered = tcp_newly_delivered(sk, delivered, flag); - lost = tp->lost - lost; /* freshly marked lost */ - rs.is_ack_delayed = !!(flag & FLAG_ACK_MAYBE_DELAYED); -+ rs.is_ece = !!(flag & FLAG_ECE); - tcp_rate_gen(sk, delivered, lost, is_sack_reneg, sack_state.rate); - tcp_cong_control(sk, ack, delivered, flag, sack_state.rate); - tcp_xmit_recovery(sk, rexmit); -@@ -5509,13 +5527,14 @@ static void __tcp_ack_snd_check(struct sock *sk, int ofo_possible) - - /* More than one full frame received... */ - if (((tp->rcv_nxt - tp->rcv_wup) > inet_csk(sk)->icsk_ack.rcv_mss && -+ (tp->fast_ack_mode == 1 || - /* ... and right edge of window advances far enough. - * (tcp_recvmsg() will send ACK otherwise). - * If application uses SO_RCVLOWAT, we want send ack now if - * we have not received enough bytes to satisfy the condition. - */ -- (tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat || -- __tcp_select_window(sk) >= tp->rcv_wnd)) || -+ (tp->rcv_nxt - tp->copied_seq < sk->sk_rcvlowat || -+ __tcp_select_window(sk) >= tp->rcv_wnd))) || - /* We ACK each frame or... */ - tcp_in_quickack_mode(sk) || - /* Protocol state mandates a one-time immediate ACK */ -diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c -index c69f4d966024..a9ceec2702b2 100644 ---- a/net/ipv4/tcp_output.c -+++ b/net/ipv4/tcp_output.c -@@ -375,7 +375,8 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, - th->cwr = 1; - skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN; - } -- } else if (!tcp_ca_needs_ecn(sk)) { -+ } else if (!(tp->ecn_flags & TCP_ECN_ECT_PERMANENT) && -+ !tcp_ca_needs_ecn(sk)) { - /* ACK or retransmitted segment: clear ECT|CE */ - INET_ECN_dontxmit(sk); - } -@@ -1533,7 +1533,7 @@ - { - struct tcp_sock *tp = tcp_sk(sk); - struct sk_buff *buff; -- int old_factor; -+ int old_factor, inflight_prev; - long limit; - int nlen; - u8 flags; -@@ -1610,6 +1611,15 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, - - if (diff) - tcp_adjust_pcount(sk, skb, diff); -+ -+ /* Set buff tx.in_flight as if buff were sent by itself. */ -+ inflight_prev = TCP_SKB_CB(skb)->tx.in_flight - old_factor; -+ if (WARN_ONCE(inflight_prev < 0, -+ "inconsistent: tx.in_flight: %u old_factor: %d", -+ TCP_SKB_CB(skb)->tx.in_flight, old_factor)) -+ inflight_prev = 0; -+ TCP_SKB_CB(buff)->tx.in_flight = inflight_prev + -+ tcp_skb_pcount(buff); - } - - /* Link BUFF into the send queue. */ -@@ -1993,13 +2003,12 @@ static u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, - static u32 tcp_tso_segs(struct sock *sk, unsigned int mss_now) - { - const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; -- u32 min_tso, tso_segs; -- -- min_tso = ca_ops->min_tso_segs ? -- ca_ops->min_tso_segs(sk) : -- READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); -+ u32 tso_segs; - -- tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); -+ tso_segs = ca_ops->tso_segs ? -+ ca_ops->tso_segs(sk, mss_now) : -+ tcp_tso_autosize(sk, mss_now, -+ READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs)); - return min_t(u32, tso_segs, sk->sk_gso_max_segs); - } - -@@ -2635,6 +2644,7 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, - skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); - list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); - tcp_init_tso_segs(skb, mss_now); -+ tcp_set_tx_in_flight(sk, skb); - goto repair; /* Skip network transmission */ - } - -diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c -index a8f6d9d06f2e..a8b4c9504570 100644 ---- a/net/ipv4/tcp_rate.c -+++ b/net/ipv4/tcp_rate.c -@@ -34,6 +34,24 @@ - * ready to send in the write queue. - */ - -+void tcp_set_tx_in_flight(struct sock *sk, struct sk_buff *skb) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ u32 in_flight; -+ -+ /* Check, sanitize, and record packets in flight after skb was sent. */ -+ in_flight = tcp_packets_in_flight(tp) + tcp_skb_pcount(skb); -+ if (WARN_ONCE(in_flight > TCPCB_IN_FLIGHT_MAX, -+ "insane in_flight %u cc %s mss %u " -+ "cwnd %u pif %u %u %u %u\n", -+ in_flight, inet_csk(sk)->icsk_ca_ops->name, -+ tp->mss_cache, tp->snd_cwnd, -+ tp->packets_out, tp->retrans_out, -+ tp->sacked_out, tp->lost_out)) -+ in_flight = TCPCB_IN_FLIGHT_MAX; -+ TCP_SKB_CB(skb)->tx.in_flight = in_flight; -+} -+ - /* Snapshot the current delivery information in the skb, to generate - * a rate sample later when the skb is (s)acked in tcp_rate_skb_delivered(). - */ -@@ -66,7 +84,9 @@ void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb) - TCP_SKB_CB(skb)->tx.delivered_mstamp = tp->delivered_mstamp; - TCP_SKB_CB(skb)->tx.delivered = tp->delivered; - TCP_SKB_CB(skb)->tx.delivered_ce = tp->delivered_ce; -+ TCP_SKB_CB(skb)->tx.lost = tp->lost; - TCP_SKB_CB(skb)->tx.is_app_limited = tp->app_limited ? 1 : 0; -+ tcp_set_tx_in_flight(sk, skb); - } - - /* When an skb is sacked or acked, we fill in the rate sample with the (prior) -@@ -91,18 +111,21 @@ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, - if (!rs->prior_delivered || - tcp_skb_sent_after(tx_tstamp, tp->first_tx_mstamp, - scb->end_seq, rs->last_end_seq)) { -+ rs->prior_lost = scb->tx.lost; - rs->prior_delivered_ce = scb->tx.delivered_ce; - rs->prior_delivered = scb->tx.delivered; - rs->prior_mstamp = scb->tx.delivered_mstamp; - rs->is_app_limited = scb->tx.is_app_limited; - rs->is_retrans = scb->sacked & TCPCB_RETRANS; - rs->last_end_seq = scb->end_seq; -+ rs->tx_in_flight = scb->tx.in_flight; - - /* Record send time of most recently ACKed packet: */ - tp->first_tx_mstamp = tx_tstamp; - /* Find the duration of the "send phase" of this window: */ -- rs->interval_us = tcp_stamp_us_delta(tp->first_tx_mstamp, -- scb->tx.first_tx_mstamp); -+ rs->interval_us = tcp_stamp32_us_delta( -+ tp->first_tx_mstamp, -+ scb->tx.first_tx_mstamp); - - } - /* Mark off the skb delivered once it's sacked to avoid being -@@ -144,6 +167,7 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, - return; - } - rs->delivered = tp->delivered - rs->prior_delivered; -+ rs->lost = tp->lost - rs->prior_lost; - - rs->delivered_ce = tp->delivered_ce - rs->prior_delivered_ce; - /* delivered_ce occupies less than 32 bits in the skb control block */ -@@ -155,7 +179,7 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, - * longer phase. - */ - snd_us = rs->interval_us; /* send phase */ -- ack_us = tcp_stamp_us_delta(tp->tcp_mstamp, -+ ack_us = tcp_stamp32_us_delta(tp->tcp_mstamp, - rs->prior_mstamp); /* ack phase */ - rs->interval_us = max(snd_us, ack_us); - -diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c -index cb79127f45c3..70e4de876a7f 100644 ---- a/net/ipv4/tcp_timer.c -+++ b/net/ipv4/tcp_timer.c -@@ -605,6 +605,7 @@ void tcp_write_timer_handler(struct sock *sk) - return; - } - -+ tcp_rate_check_app_limited(sk); - tcp_mstamp_refresh(tcp_sk(sk)); - event = icsk->icsk_pending; - ---- a/net/ipv4/tcp_input.c -+++ b/net/ipv4/tcp_input.c -@@ -287,7 +287,7 @@ - icsk->icsk_ack.quick = quickacks; - } - -+void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks) --static void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks) - { - struct inet_connection_sock *icsk = inet_csk(sk); - -@@ -295,6 +299,7 @@ - inet_csk_exit_pingpong_mode(sk); - icsk->icsk_ack.ato = TCP_ATO_MIN; - } -+EXPORT_SYMBOL(tcp_enter_quickack_mode); - - /* Send ACKs quickly, if "quick" count is not exhausted - * and the session is not interactive. ---- a/include/net/tcp.h -+++ b/include/net/tcp.h -@@ -350,6 +350,7 @@ - struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, gfp_t gfp, - bool force_schedule); - -+void tcp_enter_quickack_mode(struct sock *sk, unsigned int max_quickacks); - static inline void tcp_dec_quickack_mode(struct sock *sk) - { - struct inet_connection_sock *icsk = inet_csk(sk); |