diff options
Diffstat (limited to 'SOURCES/cachy-bbr3.patch')
| -rw-r--r-- | SOURCES/cachy-bbr3.patch | 3386 |
1 files changed, 0 insertions, 3386 deletions
diff --git a/SOURCES/cachy-bbr3.patch b/SOURCES/cachy-bbr3.patch deleted file mode 100644 index 51633e0..0000000 --- a/SOURCES/cachy-bbr3.patch +++ /dev/null @@ -1,3386 +0,0 @@ -From b8584936a7a1eb2149d0c10de2ac05ca7acc5c9f Mon Sep 17 00:00:00 2001 -From: Peter Jung <admin@ptr1337.dev> -Date: Sat, 3 Aug 2024 09:32:56 +0200 -Subject: [PATCH 02/12] bbr3 - -Signed-off-by: Peter Jung <admin@ptr1337.dev> ---- - include/linux/tcp.h | 4 +- - include/net/inet_connection_sock.h | 4 +- - include/net/tcp.h | 72 +- - include/uapi/linux/inet_diag.h | 23 + - include/uapi/linux/rtnetlink.h | 4 +- - include/uapi/linux/tcp.h | 1 + - net/ipv4/Kconfig | 21 +- - net/ipv4/bpf_tcp_ca.c | 9 +- - net/ipv4/tcp.c | 3 + - net/ipv4/tcp_bbr.c | 2230 +++++++++++++++++++++------- - net/ipv4/tcp_cong.c | 1 + - net/ipv4/tcp_input.c | 40 +- - net/ipv4/tcp_minisocks.c | 2 + - net/ipv4/tcp_output.c | 48 +- - net/ipv4/tcp_rate.c | 30 +- - net/ipv4/tcp_timer.c | 1 + - 16 files changed, 1940 insertions(+), 553 deletions(-) - -diff --git a/include/linux/tcp.h b/include/linux/tcp.h -index 6a5e08b937b3..27aab715490e 100644 ---- a/include/linux/tcp.h -+++ b/include/linux/tcp.h -@@ -369,7 +369,9 @@ 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 ? */ -+ tlp_orig_data_app_limited:1, /* app-limited before TLP rtx? */ -+ unused:2; - u8 thin_lto : 1,/* Use linear timeouts for thin streams */ - fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ - fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ -diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h -index c0deaafebfdc..d53f042d936e 100644 ---- a/include/net/inet_connection_sock.h -+++ b/include/net/inet_connection_sock.h -@@ -137,8 +137,8 @@ struct inet_connection_sock { - u32 icsk_probes_tstamp; - u32 icsk_user_timeout; - -- u64 icsk_ca_priv[104 / sizeof(u64)]; --#define ICSK_CA_PRIV_SIZE sizeof_field(struct inet_connection_sock, icsk_ca_priv) -+#define ICSK_CA_PRIV_SIZE (144) -+ u64 icsk_ca_priv[ICSK_CA_PRIV_SIZE / sizeof(u64)]; - }; - - #define ICSK_TIME_RETRANS 1 /* Retransmit timer */ -diff --git a/include/net/tcp.h b/include/net/tcp.h -index 32815a40dea1..109b8d1ddc31 100644 ---- a/include/net/tcp.h -+++ b/include/net/tcp.h -@@ -375,6 +375,8 @@ 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_LOW 16 -+#define TCP_ECN_ECT_PERMANENT 32 - - enum tcp_tw_status { - TCP_TW_SUCCESS = 0, -@@ -779,6 +781,15 @@ static inline void tcp_fast_path_check(struct sock *sk) - - u32 tcp_delack_max(const struct sock *sk); - -+static inline void tcp_set_ecn_low_from_dst(struct sock *sk, -+ const struct dst_entry *dst) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ -+ if (dst_feature(dst, RTAX_FEATURE_ECN_LOW)) -+ tp->ecn_flags |= TCP_ECN_LOW; -+} -+ - /* Compute the actual rto_min value */ - static inline u32 tcp_rto_min(const struct sock *sk) - { -@@ -884,6 +895,11 @@ 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); -+} -+ - /* provide the departure time in us unit */ - static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb) - { -@@ -973,9 +989,14 @@ 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; -@@ -1079,6 +1100,7 @@ enum tcp_ca_event { - CA_EVENT_LOSS, /* loss timeout */ - CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ - CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ -+ CA_EVENT_TLP_RECOVERY, /* a lost segment was repaired by TLP probe */ - }; - - /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ -@@ -1101,7 +1123,11 @@ 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; - -@@ -1121,10 +1147,13 @@ 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*/ -+ s32 delivered_ce; /* packets delivered w/ CE mark over interval */ - long interval_us; /* time for tp->delivered to incr "delivered" */ - u32 snd_interval_us; /* snd interval for delivered packets */ - u32 rcv_interval_us; /* rcv interval for delivered packets */ -@@ -1135,7 +1164,9 @@ struct rate_sample { - u32 last_end_seq; /* end_seq of most recently ACKed packet */ - bool is_app_limited; /* is sample from packet with bubble in pipe? */ - bool is_retrans; /* is sample from retransmission? */ -+ bool is_acking_tlp_retrans_seq; /* ACKed a TLP retransmit sequence? */ - bool is_ack_delayed; /* is this (likely) a delayed ACK? */ -+ bool is_ece; /* did this ACK have ECN marked? */ - }; - - struct tcp_congestion_ops { -@@ -1159,8 +1190,11 @@ 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) -@@ -1226,6 +1260,14 @@ 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); -@@ -1245,6 +1287,7 @@ 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); -@@ -1257,6 +1300,21 @@ static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2) - return t1 > t2 || (t1 == t2 && after(seq1, seq2)); - } - -+/* If a retransmit failed due to local qdisc congestion or other local issues, -+ * then we may have called tcp_set_skb_tso_segs() to increase the number of -+ * segments in the skb without increasing the tx.in_flight. In all other cases, -+ * the tx.in_flight should be at least as big as the pcount of the sk_buff. We -+ * do not have the state to know whether a retransmit failed due to local qdisc -+ * congestion or other local issues, so to avoid spurious warnings we consider -+ * that any skb marked lost may have suffered that fate. -+ */ -+static inline bool tcp_skb_tx_in_flight_is_suspicious(u32 skb_pcount, -+ u32 skb_sacked_flags, -+ u32 tx_in_flight) -+{ -+ return (skb_pcount > tx_in_flight) && !(skb_sacked_flags & TCPCB_LOST); -+} -+ - /* These functions determine how the current flow behaves in respect of SACK - * handling. SACK is negotiated with the peer, and therefore it can vary - * between different flows. -@@ -2419,7 +2477,7 @@ struct tcp_plb_state { - u8 consec_cong_rounds:5, /* consecutive congested rounds */ - unused:3; - u32 pause_until; /* jiffies32 when PLB can resume rerouting */ --}; -+} __attribute__ ((__packed__)); - - static inline void tcp_plb_init(const struct sock *sk, - struct tcp_plb_state *plb) -diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h -index 50655de04c9b..82f8bd8f0d16 100644 ---- a/include/uapi/linux/inet_diag.h -+++ b/include/uapi/linux/inet_diag.h -@@ -229,6 +229,29 @@ struct tcp_bbr_info { - __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; /* BBR algorithm version */ -+ __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 */ -+}; -+ -+/* TCP BBR congestion control bbr_phase as reported in netlink/ss stats. */ -+enum tcp_bbr_phase { -+ BBR_PHASE_INVALID = 0, -+ BBR_PHASE_STARTUP = 1, -+ BBR_PHASE_DRAIN = 2, -+ BBR_PHASE_PROBE_RTT = 3, -+ BBR_PHASE_PROBE_BW_UP = 4, -+ BBR_PHASE_PROBE_BW_DOWN = 5, -+ BBR_PHASE_PROBE_BW_CRUISE = 6, -+ BBR_PHASE_PROBE_BW_REFILL = 7, - }; - - union tcp_cc_info { -diff --git a/include/uapi/linux/rtnetlink.h b/include/uapi/linux/rtnetlink.h -index 3b687d20c9ed..a7c30c243b54 100644 ---- a/include/uapi/linux/rtnetlink.h -+++ b/include/uapi/linux/rtnetlink.h -@@ -507,12 +507,14 @@ enum { - #define RTAX_FEATURE_TIMESTAMP (1 << 2) /* unused */ - #define RTAX_FEATURE_ALLFRAG (1 << 3) /* unused */ - #define RTAX_FEATURE_TCP_USEC_TS (1 << 4) -+#define RTAX_FEATURE_ECN_LOW (1 << 5) - - #define RTAX_FEATURE_MASK (RTAX_FEATURE_ECN | \ - RTAX_FEATURE_SACK | \ - RTAX_FEATURE_TIMESTAMP | \ - RTAX_FEATURE_ALLFRAG | \ -- RTAX_FEATURE_TCP_USEC_TS) -+ RTAX_FEATURE_TCP_USEC_TS | \ -+ RTAX_FEATURE_ECN_LOW) - - struct rta_session { - __u8 proto; -diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h -index dbf896f3146c..4702cd2f1ffc 100644 ---- a/include/uapi/linux/tcp.h -+++ b/include/uapi/linux/tcp.h -@@ -178,6 +178,7 @@ enum tcp_fastopen_client_fail { - #define TCPI_OPT_ECN_SEEN 16 /* we received at least one packet with ECT */ - #define TCPI_OPT_SYN_DATA 32 /* SYN-ACK acked data in SYN sent or rcvd */ - #define TCPI_OPT_USEC_TS 64 /* usec timestamps */ -+#define TCPI_OPT_ECN_LOW 128 /* Low-latency ECN configured at init */ - - /* - * Sender's congestion state indicating normal or abnormal situations -diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig -index 8e94ed7c56a0..50dc9970cad2 100644 ---- a/net/ipv4/Kconfig -+++ b/net/ipv4/Kconfig -@@ -668,15 +668,18 @@ config TCP_CONG_BBR - default n - help - -- BBR (Bottleneck Bandwidth and RTT) TCP congestion control aims to -- maximize network utilization and minimize queues. It builds an explicit -- model of the bottleneck delivery rate and path round-trip propagation -- delay. It tolerates packet loss and delay unrelated to congestion. It -- can operate over LAN, WAN, cellular, wifi, or cable modem links. 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 the fq -- ("Fair Queue") pacing packet scheduler. -+ BBR (Bottleneck Bandwidth and RTT) 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. It can operate over LAN, WAN, -+ cellular, wifi, or cable modem links, and can use shallow-threshold -+ ECN signals. It can coexist to some degree 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" -diff --git a/net/ipv4/bpf_tcp_ca.c b/net/ipv4/bpf_tcp_ca.c -index 18227757ec0c..f180befc28bd 100644 ---- a/net/ipv4/bpf_tcp_ca.c -+++ b/net/ipv4/bpf_tcp_ca.c -@@ -305,11 +305,15 @@ static void bpf_tcp_ca_pkts_acked(struct sock *sk, const struct ack_sample *samp - { - } - --static u32 bpf_tcp_ca_min_tso_segs(struct sock *sk) -+static u32 bpf_tcp_ca_tso_segs(struct sock *sk, unsigned int mss_now) - { - return 0; - } - -+static void bpf_tcp_ca_skb_marked_lost(struct sock *sk, const struct sk_buff *skb) -+{ -+} -+ - static void bpf_tcp_ca_cong_control(struct sock *sk, u32 ack, int flag, - const struct rate_sample *rs) - { -@@ -340,7 +344,8 @@ static struct tcp_congestion_ops __bpf_ops_tcp_congestion_ops = { - .cwnd_event = bpf_tcp_ca_cwnd_event, - .in_ack_event = bpf_tcp_ca_in_ack_event, - .pkts_acked = bpf_tcp_ca_pkts_acked, -- .min_tso_segs = bpf_tcp_ca_min_tso_segs, -+ .tso_segs = bpf_tcp_ca_tso_segs, -+ .skb_marked_lost = bpf_tcp_ca_skb_marked_lost, - .cong_control = bpf_tcp_ca_cong_control, - .undo_cwnd = bpf_tcp_ca_undo_cwnd, - .sndbuf_expand = bpf_tcp_ca_sndbuf_expand, -diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c -index ec6911034138..df7731a30198 100644 ---- a/net/ipv4/tcp.c -+++ b/net/ipv4/tcp.c -@@ -3120,6 +3120,7 @@ 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 */ -@@ -3846,6 +3847,8 @@ void tcp_get_info(struct sock *sk, struct tcp_info *info) - info->tcpi_options |= TCPI_OPT_ECN; - if (tp->ecn_flags & TCP_ECN_SEEN) - info->tcpi_options |= TCPI_OPT_ECN_SEEN; -+ if (tp->ecn_flags & TCP_ECN_LOW) -+ info->tcpi_options |= TCPI_OPT_ECN_LOW; - if (tp->syn_data_acked) - info->tcpi_options |= TCPI_OPT_SYN_DATA; - if (tp->tcp_usec_ts) -diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c -index 760941e55153..a180fa648d5e 100644 ---- a/net/ipv4/tcp_bbr.c -+++ b/net/ipv4/tcp_bbr.c -@@ -1,18 +1,19 @@ --/* Bottleneck Bandwidth and RTT (BBR) congestion control -+/* BBR (Bottleneck Bandwidth and RTT) congestion control - * -- * BBR congestion control computes the sending rate based on the delivery -- * rate (throughput) estimated from ACKs. In a nutshell: -+ * BBR 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 shallow-threshold 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. - * -- * On each ACK, update our model of the network path: -- * bottleneck_bandwidth = windowed_max(delivered / elapsed, 10 round trips) -- * min_rtt = windowed_min(rtt, 10 seconds) -- * pacing_rate = pacing_gain * bottleneck_bandwidth -- * cwnd = max(cwnd_gain * bottleneck_bandwidth * min_rtt, 4) -- * -- * The core algorithm does not react directly to packet losses or delays, -- * although BBR may adjust the size of next send per ACK when loss is -- * observed, or adjust the sending rate if it estimates there is a -- * traffic policer, in order to keep the drop rate reasonable. -+ * 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: - * -@@ -65,6 +66,13 @@ - #include <linux/random.h> - #include <linux/win_minmax.h> - -+#include <trace/events/tcp.h> -+#include "tcp_dctcp.h" -+ -+#define BBR_VERSION 3 -+ -+#define bbr_param(sk,name) (bbr_ ## name) -+ - /* 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. -@@ -85,36 +93,41 @@ enum bbr_mode { - 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 */ -- struct minmax bw; /* Max recent delivery rate in pkts/uS << 24 */ -- u32 rtt_cnt; /* count of packet-timed rounds elapsed */ -+ u32 probe_rtt_min_us; /* min RTT in probe_rtt_win_ms win */ -+ u32 probe_rtt_min_stamp; /* timestamp of probe_rtt_min_us*/ - u32 next_rtt_delivered; /* scb->tx.delivered at end of round */ - u64 cycle_mstamp; /* time of this cycle phase start */ -- u32 mode:3, /* current bbr_mode in state machine */ -+ u32 mode:2, /* 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? */ - idle_restart:1, /* restarting after idle? */ - probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */ -- unused:13, -- lt_is_sampling:1, /* taking long-term ("LT") samples now? */ -- lt_rtt_cnt:7, /* round trips in long-term interval */ -- lt_use_bw:1; /* use lt_bw as our bw estimate? */ -- u32 lt_bw; /* LT est delivery rate in pkts/uS << 24 */ -- u32 lt_last_delivered; /* LT intvl start: tp->delivered */ -- u32 lt_last_stamp; /* LT intvl start: tp->delivered_mstamp */ -- u32 lt_last_lost; /* LT intvl start: tp->lost */ -+ init_cwnd:7, /* initial cwnd */ -+ unused_1:10; - u32 pacing_gain:10, /* current gain for setting pacing rate */ - cwnd_gain:10, /* 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 */ -- cycle_idx:3, /* current index in pacing_gain cycle array */ -+ cycle_idx:2, /* current index in pacing_gain cycle array */ - has_seen_rtt:1, /* have we seen an RTT sample yet? */ -- unused_b:5; -+ unused_2:6; - u32 prior_cwnd; /* prior cwnd upon entering loss recovery */ - u32 full_bw; /* recent bw, to estimate if pipe is full */ - -@@ -124,19 +137,67 @@ struct bbr { - 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 */ -- unused_c:6; -+ /* BBR v3 state: */ -+ full_bw_now:1, /* recently reached full bw plateau? */ -+ 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? */ -+ unused_3:1; -+ 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]; /* max recent measured bw sample */ -+ 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 prior_rcv_nxt; /* tp->rcv_nxt when CE state last changed */ -+ 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 */ -+ -+ u8 unused_4; /* to preserve alignment */ -+ struct tcp_plb_state plb; - }; - --#define CYCLE_LEN 8 /* number of phases in a pacing gain cycle */ -+struct bbr_context { -+ u32 sample_bw; -+}; - --/* Window length of bw filter (in rounds): */ --static const int bbr_bw_rtts = CYCLE_LEN + 2; - /* Window length of min_rtt filter (in sec): */ - static const u32 bbr_min_rtt_win_sec = 10; - /* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode: */ - static const u32 bbr_probe_rtt_mode_ms = 200; --/* Skip TSO below the following bandwidth (bits/sec): */ --static const int bbr_min_tso_rate = 1200000; -+/* Window length of probe_rtt_min_us filter (in ms), and consequently the -+ * typical interval between PROBE_RTT mode entries. The default is 5000ms. -+ * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC -+ */ -+static const u32 bbr_probe_rtt_win_ms = 5000; -+/* Proportion of cwnd to estimated BDP in PROBE_RTT, in units of BBR_UNIT: */ -+static const u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2; -+ -+/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting -+ * in bigger TSO bursts. 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 const u32 bbr_tso_rtt_shift = 9; - - /* 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 -@@ -146,13 +207,15 @@ static const int bbr_min_tso_rate = 1200000; - */ - 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 -+/* We use a startup_pacing_gain of 4*ln(2) because it's the smallest value - * that will allow a smoothly increasing pacing rate that will double each RTT - * and send the same number of packets per RTT that an un-paced, slow-starting - * Reno or CUBIC flow would: - */ --static const int bbr_high_gain = BBR_UNIT * 2885 / 1000 + 1; --/* The pacing gain of 1/high_gain in BBR_DRAIN is calculated to typically drain -+static const int bbr_startup_pacing_gain = BBR_UNIT * 277 / 100 + 1; -+/* The gain for deriving startup cwnd: */ -+static const int bbr_startup_cwnd_gain = BBR_UNIT * 2; -+/* The pacing gain in BBR_DRAIN is calculated to typically drain - * the queue created in BBR_STARTUP in a single round: - */ - static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885; -@@ -160,13 +223,17 @@ static const int bbr_drain_gain = BBR_UNIT * 1000 / 2885; - static const int bbr_cwnd_gain = BBR_UNIT * 2; - /* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw: */ - static const int bbr_pacing_gain[] = { -- BBR_UNIT * 5 / 4, /* probe for more available bw */ -- BBR_UNIT * 3 / 4, /* drain queue and/or yield bw to other flows */ -- BBR_UNIT, BBR_UNIT, BBR_UNIT, /* cruise at 1.0*bw to utilize pipe, */ -- BBR_UNIT, BBR_UNIT, BBR_UNIT /* without creating excess queue... */ -+ BBR_UNIT * 5 / 4, /* UP: probe for more available bw */ -+ BBR_UNIT * 91 / 100, /* DOWN: drain queue and/or yield bw */ -+ BBR_UNIT, /* CRUISE: try to use pipe w/ some headroom */ -+ BBR_UNIT, /* REFILL: refill pipe to estimated 100% */ -+}; -+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% */ - }; --/* Randomize the starting gain cycling phase over N phases: */ --static const u32 bbr_cycle_rand = 7; - - /* Try to keep at least this many packets in flight, if things go smoothly. For - * smooth functioning, a sliding window protocol ACKing every other packet -@@ -174,24 +241,12 @@ static const u32 bbr_cycle_rand = 7; - */ - static const u32 bbr_cwnd_min_target = 4; - --/* To estimate if BBR_STARTUP mode (i.e. high_gain) has filled pipe... */ -+/* To estimate if BBR_STARTUP or BBR_BW_PROBE_UP has filled pipe... */ - /* If bw has increased significantly (1.25x), there may be more bw available: */ - static const u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4; - /* But after 3 rounds w/o significant bw growth, estimate pipe is full: */ - static const u32 bbr_full_bw_cnt = 3; - --/* "long-term" ("LT") bandwidth estimator parameters... */ --/* The minimum number of rounds in an LT bw sampling interval: */ --static const u32 bbr_lt_intvl_min_rtts = 4; --/* If lost/delivered ratio > 20%, interval is "lossy" and we may be policed: */ --static const u32 bbr_lt_loss_thresh = 50; --/* If 2 intervals have a bw ratio <= 1/8, their bw is "consistent": */ --static const u32 bbr_lt_bw_ratio = BBR_UNIT / 8; --/* If 2 intervals have a bw diff <= 4 Kbit/sec their bw is "consistent": */ --static const u32 bbr_lt_bw_diff = 4000 / 8; --/* If we estimate we're policed, use lt_bw for this many round trips: */ --static const u32 bbr_lt_bw_max_rtts = 48; -- - /* Gain factor for adding extra_acked to target cwnd: */ - static const int bbr_extra_acked_gain = BBR_UNIT; - /* Window length of extra_acked window. */ -@@ -201,8 +256,121 @@ static const u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20; - /* Time period for clamping cwnd increment due to ack aggregation */ - static const u32 bbr_extra_acked_max_us = 100 * 1000; - -+/* Flags to control BBR ECN-related behavior... */ -+ -+/* Ensure ACKs only ACK packets with consistent ECN CE status? */ -+static const bool bbr_precise_ece_ack = true; -+ -+/* Max RTT (in usec) at which to use sender-side ECN logic. -+ * Disabled when 0 (ECN allowed at any RTT). -+ */ -+static const u32 bbr_ecn_max_rtt_us = 5000; -+ -+/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE. -+ * No loss response when 0. -+ */ -+static const u32 bbr_beta = BBR_UNIT * 30 / 100; -+ -+/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE (1/16 = 6.25%) */ -+static const u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16; -+ -+/* The initial value for ecn_alpha; 1.0 allows a flow to respond quickly -+ * to congestion if the bottleneck is congested when the flow starts up. -+ */ -+static const u32 bbr_ecn_alpha_init = BBR_UNIT; -+ -+/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE. -+ * No ECN based bounding when 0. -+ */ -+static const 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. -+ */ -+static const u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2; /* 1/2 = 50% */ -+ -+/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN -+ * clears then make the first round's increment to inflight_hi the following -+ * fraction of inflight_hi. -+ */ -+static const u32 bbr_ecn_reprobe_gain = BBR_UNIT * 1 / 2; -+ -+/* Estimate bw probing has gone too far if loss rate exceeds this level. */ -+static const u32 bbr_loss_thresh = BBR_UNIT * 2 / 100; /* 2% loss */ -+ -+/* Slow down for a packet loss recovered by TLP? */ -+static const bool bbr_loss_probe_recovery = true; -+ -+/* 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. -+ */ -+static const u32 bbr_full_loss_cnt = 6; -+ -+/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh -+ * meets this count. -+ */ -+static const u32 bbr_full_ecn_cnt = 2; -+ -+/* Fraction of unutilized headroom to try to leave in path upon high loss. */ -+static const u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100; -+ -+/* How much do we increase cwnd_gain when probing for bandwidth in -+ * BBR_BW_PROBE_UP? This specifies the increment in units of -+ * BBR_UNIT/4. The default is 1, meaning 0.25. -+ * The min value is 0 (meaning 0.0); max is 3 (meaning 0.75). -+ */ -+static const u32 bbr_bw_probe_cwnd_gain = 1; -+ -+/* 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 const u32 bbr_bw_probe_max_rounds = 63; -+ -+/* Max amount of randomness to inject in round counting for Reno-coexistence. -+ */ -+static const 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 const u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC; /* 2 secs */ -+ -+/* Use BBR-native probes spread over this many usec: */ -+static const u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC; /* 1 secs */ -+ -+/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */ -+static const bool bbr_fast_path = true; -+ -+/* Use fast ack mode? */ -+static const bool bbr_fast_ack_mode = true; -+ -+static u32 bbr_max_bw(const struct sock *sk); -+static u32 bbr_bw(const struct sock *sk); -+static void bbr_exit_probe_rtt(struct sock *sk); -+static void bbr_reset_congestion_signals(struct sock *sk); -+static void bbr_run_loss_probe_recovery(struct sock *sk); -+ - static void bbr_check_probe_rtt_done(struct sock *sk); - -+/* This connection can use ECN if both endpoints have signaled ECN support in -+ * the handshake and the per-route settings indicated this is a -+ * shallow-threshold ECN environment, meaning both: -+ * (a) ECN CE marks indicate low-latency/shallow-threshold congestion, and -+ * (b) TCP endpoints provide precise ACKs that only ACK data segments -+ * with consistent ECN CE status -+ */ -+static bool bbr_can_use_ecn(const struct sock *sk) -+{ -+ return (tcp_sk(sk)->ecn_flags & TCP_ECN_OK) && -+ (tcp_sk(sk)->ecn_flags & TCP_ECN_LOW); -+} -+ - /* Do we estimate that STARTUP filled the pipe? */ - static bool bbr_full_bw_reached(const struct sock *sk) - { -@@ -214,17 +382,17 @@ static bool bbr_full_bw_reached(const struct sock *sk) - /* 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); -+ const struct bbr *bbr = inet_csk_ca(sk); - -- return minmax_get(&bbr->bw); -+ 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); -+ const struct bbr *bbr = inet_csk_ca(sk); - -- return bbr->lt_use_bw ? bbr->lt_bw : bbr_max_bw(sk); -+ return min(bbr_max_bw(sk), bbr->bw_lo); - } - - /* Return maximum extra acked in past k-2k round trips, -@@ -241,15 +409,23 @@ static u16 bbr_extra_acked(const struct sock *sk) - * 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) -+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 - bbr_pacing_margin_percent); -- return rate >> BW_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); - } - - /* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */ -@@ -257,12 +433,13 @@ 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); -+ rate = bbr_rate_bytes_per_sec(sk, rate, gain, -+ bbr_pacing_margin_percent); - rate = min_t(u64, rate, READ_ONCE(sk->sk_max_pacing_rate)); - return rate; - } - --/* Initialize pacing rate to: high_gain * init_cwnd / RTT. */ -+/* Initialize pacing rate to: startup_pacing_gain * init_cwnd / RTT. */ - static void bbr_init_pacing_rate_from_rtt(struct sock *sk) - { - struct tcp_sock *tp = tcp_sk(sk); -@@ -279,7 +456,7 @@ static void bbr_init_pacing_rate_from_rtt(struct sock *sk) - bw = (u64)tcp_snd_cwnd(tp) * BW_UNIT; - do_div(bw, rtt_us); - WRITE_ONCE(sk->sk_pacing_rate, -- bbr_bw_to_pacing_rate(sk, bw, bbr_high_gain)); -+ bbr_bw_to_pacing_rate(sk, bw, bbr_param(sk, startup_pacing_gain))); - } - - /* Pace using current bw estimate and a gain factor. */ -@@ -295,26 +472,48 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) - WRITE_ONCE(sk->sk_pacing_rate, rate); - } - --/* override sysctl_tcp_min_tso_segs */ --__bpf_kfunc static u32 bbr_min_tso_segs(struct sock *sk) -+/* Return the number of segments BBR would like in a TSO/GSO skb, given a -+ * particular max gso size as a constraint. TODO: make this simpler and more -+ * consistent by switching bbr to just call tcp_tso_autosize(). -+ */ -+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 = READ_ONCE(sk->sk_pacing_rate) >> READ_ONCE(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_param(sk, tso_rtt_shift)) { -+ r = bbr->min_rtt_us >> bbr_param(sk, tso_rtt_shift); -+ if (r < BITS_PER_TYPE(u32)) /* prevent undefined behavior */ -+ bytes += GSO_LEGACY_MAX_SIZE >> r; -+ } -+ -+ bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER); -+ segs = max_t(u32, bytes / mss_now, -+ sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); -+ return segs; -+} -+ -+/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */ -+__bpf_kfunc static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) - { -- return READ_ONCE(sk->sk_pacing_rate) < (bbr_min_tso_rate >> 3) ? 1 : 2; -+ 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, -- READ_ONCE(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 */ -@@ -334,7 +533,9 @@ __bpf_kfunc 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) { -+ if (event == CA_EVENT_TX_START) { -+ if (!tp->app_limited) -+ return; - bbr->idle_restart = 1; - bbr->ack_epoch_mstamp = tp->tcp_mstamp; - bbr->ack_epoch_acked = 0; -@@ -345,6 +546,16 @@ __bpf_kfunc static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event) - 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_can_use_ecn(sk) && -+ bbr_param(sk, precise_ece_ack)) { -+ u32 state = bbr->ce_state; -+ dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state); -+ bbr->ce_state = state; -+ } else if (event == CA_EVENT_TLP_RECOVERY && -+ bbr_param(sk, loss_probe_recovery)) { -+ bbr_run_loss_probe_recovery(sk); - } - } - -@@ -367,10 +578,10 @@ static u32 bbr_bdp(struct sock *sk, u32 bw, int gain) - * default. This should only happen when the connection is not using TCP - * timestamps and has retransmitted all of the SYN/SYNACK/data packets - * ACKed so far. In this case, an RTO can cut cwnd to 1, in which -- * case we need to slow-start up toward something safe: TCP_INIT_CWND. -+ * 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 TCP_INIT_CWND; /* be safe: cap at default initial cwnd*/ -+ return bbr->init_cwnd; /* be safe: cap at initial cwnd */ - - w = (u64)bw * bbr->min_rtt_us; - -@@ -387,23 +598,23 @@ static u32 bbr_bdp(struct sock *sk, u32 bw, int gain) - * - 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, -+ * Don't worry, at low rates this won't bloat cwnd because -+ * in such cases tso_segs_goal is small. 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; - -- /* Allow enough full-sized skbs in flight to utilize end systems. */ -- cwnd += 3 * bbr_tso_segs_goal(sk); -- -- /* Reduce delayed ACKs by rounding up cwnd to the next even number. */ -- cwnd = (cwnd + 1) & ~1U; -+ tso_segs_goal = 3 * bbr_tso_segs_goal(sk); - -+ /* Allow enough full-sized skbs in flight to utilize end systems. */ -+ cwnd = max_t(u32, cwnd, tso_segs_goal); -+ cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target)); - /* Ensure gain cycling gets inflight above BDP even for small BDPs. */ -- if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == 0) -+ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) - cwnd += 2; - - return cwnd; -@@ -458,10 +669,10 @@ static u32 bbr_ack_aggregation_cwnd(struct sock *sk) - { - u32 max_aggr_cwnd, aggr_cwnd = 0; - -- if (bbr_extra_acked_gain && bbr_full_bw_reached(sk)) { -+ if (bbr_param(sk, extra_acked_gain)) { - max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us) - / BW_UNIT; -- aggr_cwnd = (bbr_extra_acked_gain * bbr_extra_acked(sk)) -+ aggr_cwnd = (bbr_param(sk, extra_acked_gain) * bbr_extra_acked(sk)) - >> BBR_SCALE; - aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd); - } -@@ -469,66 +680,27 @@ static u32 bbr_ack_aggregation_cwnd(struct sock *sk) - return aggr_cwnd; - } - --/* An optimization in BBR to reduce losses: On the first round of recovery, we -- * follow the packet conservation principle: send P packets per P packets acked. -- * After that, we slow-start and send at most 2*P packets per P packets acked. -- * After recovery finishes, or upon undo, we restore the cwnd we had when -- * recovery started (capped by the target cwnd based on estimated BDP). -- * -- * TODO(ycheng/ncardwell): implement a rate-based approach. -- */ --static bool bbr_set_cwnd_to_recover_or_restore( -- struct sock *sk, const struct rate_sample *rs, u32 acked, u32 *new_cwnd) -+/* Returns the cwnd for PROBE_RTT mode. */ -+static u32 bbr_probe_rtt_cwnd(struct sock *sk) - { -- struct tcp_sock *tp = tcp_sk(sk); -- struct bbr *bbr = inet_csk_ca(sk); -- u8 prev_state = bbr->prev_ca_state, state = inet_csk(sk)->icsk_ca_state; -- u32 cwnd = tcp_snd_cwnd(tp); -- -- /* An ACK for P pkts should release at most 2*P packets. We do this -- * in two steps. First, here we deduct the number of lost packets. -- * Then, in bbr_set_cwnd() we slow start up toward the target cwnd. -- */ -- if (rs->losses > 0) -- cwnd = max_t(s32, cwnd - rs->losses, 1); -- -- if (state == TCP_CA_Recovery && prev_state != TCP_CA_Recovery) { -- /* Starting 1st round of Recovery, so do packet conservation. */ -- bbr->packet_conservation = 1; -- bbr->next_rtt_delivered = tp->delivered; /* start round now */ -- /* Cut unused cwnd from app behavior, TSQ, or TSO deferral: */ -- cwnd = tcp_packets_in_flight(tp) + acked; -- } else if (prev_state >= TCP_CA_Recovery && state < TCP_CA_Recovery) { -- /* Exiting loss recovery; restore cwnd saved before recovery. */ -- cwnd = max(cwnd, bbr->prior_cwnd); -- bbr->packet_conservation = 0; -- } -- bbr->prev_ca_state = state; -- -- if (bbr->packet_conservation) { -- *new_cwnd = max(cwnd, tcp_packets_in_flight(tp) + acked); -- return true; /* yes, using packet conservation */ -- } -- *new_cwnd = cwnd; -- return false; -+ return max_t(u32, bbr_param(sk, cwnd_min_target), -+ bbr_bdp(sk, bbr_bw(sk), bbr_param(sk, 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 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 cwnd = tcp_snd_cwnd(tp), target_cwnd = 0; -+ u32 target_cwnd = 0; - - if (!acked) - goto done; /* no packet fully ACKed; just apply caps */ - -- if (bbr_set_cwnd_to_recover_or_restore(sk, rs, acked, &cwnd)) -- goto done; -- - target_cwnd = bbr_bdp(sk, bw, gain); - - /* Increment the cwnd to account for excess ACKed data that seems -@@ -537,74 +709,26 @@ static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs, - 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. */ -- if (bbr_full_bw_reached(sk)) /* only cut cwnd if we filled the pipe */ -- cwnd = min(cwnd + acked, target_cwnd); -- else if (cwnd < target_cwnd || tp->delivered < TCP_INIT_CWND) -- cwnd = cwnd + acked; -- cwnd = max(cwnd, bbr_cwnd_min_target); -+ /* 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; -+ } - -+ cwnd = max_t(u32, cwnd, bbr_param(sk, cwnd_min_target)); - done: -- tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp)); /* apply global cap */ -+ tcp_snd_cwnd_set(tp, min(cwnd, tp->snd_cwnd_clamp)); /* global cap */ - if (bbr->mode == BBR_PROBE_RTT) /* drain queue, refresh min_rtt */ -- tcp_snd_cwnd_set(tp, min(tcp_snd_cwnd(tp), bbr_cwnd_min_target)); --} -- --/* End cycle phase if it's time and/or we hit the phase's in-flight target. */ --static bool bbr_is_next_cycle_phase(struct sock *sk, -- const struct rate_sample *rs) --{ -- struct tcp_sock *tp = tcp_sk(sk); -- struct bbr *bbr = inet_csk_ca(sk); -- bool is_full_length = -- tcp_stamp_us_delta(tp->delivered_mstamp, bbr->cycle_mstamp) > -- bbr->min_rtt_us; -- u32 inflight, bw; -- -- /* The pacing_gain of 1.0 paces at the estimated bw to try to fully -- * use the pipe without increasing the queue. -- */ -- if (bbr->pacing_gain == BBR_UNIT) -- return is_full_length; /* just use wall clock time */ -- -- inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight); -- bw = bbr_max_bw(sk); -- -- /* A pacing_gain > 1.0 probes for bw by trying to raise inflight to at -- * least pacing_gain*BDP; this may take more than min_rtt if min_rtt is -- * small (e.g. on a LAN). We do not persist if packets are lost, since -- * a path with small buffers may not hold that much. -- */ -- if (bbr->pacing_gain > BBR_UNIT) -- return is_full_length && -- (rs->losses || /* perhaps pacing_gain*BDP won't fit */ -- inflight >= bbr_inflight(sk, bw, bbr->pacing_gain)); -- -- /* A pacing_gain < 1.0 tries to drain extra queue we added if bw -- * probing didn't find more bw. If inflight falls to match BDP then we -- * estimate queue is drained; persisting would underutilize the pipe. -- */ -- return is_full_length || -- inflight <= bbr_inflight(sk, bw, BBR_UNIT); --} -- --static void bbr_advance_cycle_phase(struct sock *sk) --{ -- struct tcp_sock *tp = tcp_sk(sk); -- struct bbr *bbr = inet_csk_ca(sk); -- -- bbr->cycle_idx = (bbr->cycle_idx + 1) & (CYCLE_LEN - 1); -- bbr->cycle_mstamp = tp->delivered_mstamp; --} -- --/* Gain cycling: cycle pacing gain to converge to fair share of available bw. */ --static void bbr_update_cycle_phase(struct sock *sk, -- const struct rate_sample *rs) --{ -- struct bbr *bbr = inet_csk_ca(sk); -- -- if (bbr->mode == BBR_PROBE_BW && bbr_is_next_cycle_phase(sk, rs)) -- bbr_advance_cycle_phase(sk); -+ tcp_snd_cwnd_set(tp, min_t(u32, tcp_snd_cwnd(tp), -+ bbr_probe_rtt_cwnd(sk))); - } - - static void bbr_reset_startup_mode(struct sock *sk) -@@ -614,191 +738,49 @@ static void bbr_reset_startup_mode(struct sock *sk) - bbr->mode = BBR_STARTUP; - } - --static void bbr_reset_probe_bw_mode(struct sock *sk) --{ -- struct bbr *bbr = inet_csk_ca(sk); -- -- bbr->mode = BBR_PROBE_BW; -- bbr->cycle_idx = CYCLE_LEN - 1 - get_random_u32_below(bbr_cycle_rand); -- bbr_advance_cycle_phase(sk); /* flip to next phase of gain cycle */ --} -- --static void bbr_reset_mode(struct sock *sk) --{ -- if (!bbr_full_bw_reached(sk)) -- bbr_reset_startup_mode(sk); -- else -- bbr_reset_probe_bw_mode(sk); --} -- --/* Start a new long-term sampling interval. */ --static void bbr_reset_lt_bw_sampling_interval(struct sock *sk) --{ -- struct tcp_sock *tp = tcp_sk(sk); -- struct bbr *bbr = inet_csk_ca(sk); -- -- bbr->lt_last_stamp = div_u64(tp->delivered_mstamp, USEC_PER_MSEC); -- bbr->lt_last_delivered = tp->delivered; -- bbr->lt_last_lost = tp->lost; -- bbr->lt_rtt_cnt = 0; --} -- --/* Completely reset long-term bandwidth sampling. */ --static void bbr_reset_lt_bw_sampling(struct sock *sk) --{ -- struct bbr *bbr = inet_csk_ca(sk); -- -- bbr->lt_bw = 0; -- bbr->lt_use_bw = 0; -- bbr->lt_is_sampling = false; -- bbr_reset_lt_bw_sampling_interval(sk); --} -- --/* Long-term bw sampling interval is done. Estimate whether we're policed. */ --static void bbr_lt_bw_interval_done(struct sock *sk, u32 bw) --{ -- struct bbr *bbr = inet_csk_ca(sk); -- u32 diff; -- -- if (bbr->lt_bw) { /* do we have bw from a previous interval? */ -- /* Is new bw close to the lt_bw from the previous interval? */ -- diff = abs(bw - bbr->lt_bw); -- if ((diff * BBR_UNIT <= bbr_lt_bw_ratio * bbr->lt_bw) || -- (bbr_rate_bytes_per_sec(sk, diff, BBR_UNIT) <= -- bbr_lt_bw_diff)) { -- /* All criteria are met; estimate we're policed. */ -- bbr->lt_bw = (bw + bbr->lt_bw) >> 1; /* avg 2 intvls */ -- bbr->lt_use_bw = 1; -- bbr->pacing_gain = BBR_UNIT; /* try to avoid drops */ -- bbr->lt_rtt_cnt = 0; -- return; -- } -- } -- bbr->lt_bw = bw; -- bbr_reset_lt_bw_sampling_interval(sk); --} -- --/* Token-bucket traffic policers are common (see "An Internet-Wide Analysis of -- * Traffic Policing", SIGCOMM 2016). BBR detects token-bucket policers and -- * explicitly models their policed rate, to reduce unnecessary losses. We -- * estimate that we're policed if we see 2 consecutive sampling intervals with -- * consistent throughput and high packet loss. If we think we're being policed, -- * set lt_bw to the "long-term" average delivery rate from those 2 intervals. -+/* See if we have reached next round trip. Upon start of the new round, -+ * returns packets delivered since previous round start plus this ACK. - */ --static void bbr_lt_bw_sampling(struct sock *sk, const struct rate_sample *rs) --{ -- struct tcp_sock *tp = tcp_sk(sk); -- struct bbr *bbr = inet_csk_ca(sk); -- u32 lost, delivered; -- u64 bw; -- u32 t; -- -- if (bbr->lt_use_bw) { /* already using long-term rate, lt_bw? */ -- if (bbr->mode == BBR_PROBE_BW && bbr->round_start && -- ++bbr->lt_rtt_cnt >= bbr_lt_bw_max_rtts) { -- bbr_reset_lt_bw_sampling(sk); /* stop using lt_bw */ -- bbr_reset_probe_bw_mode(sk); /* restart gain cycling */ -- } -- return; -- } -- -- /* Wait for the first loss before sampling, to let the policer exhaust -- * its tokens and estimate the steady-state rate allowed by the policer. -- * Starting samples earlier includes bursts that over-estimate the bw. -- */ -- if (!bbr->lt_is_sampling) { -- if (!rs->losses) -- return; -- bbr_reset_lt_bw_sampling_interval(sk); -- bbr->lt_is_sampling = true; -- } -- -- /* To avoid underestimates, reset sampling if we run out of data. */ -- if (rs->is_app_limited) { -- bbr_reset_lt_bw_sampling(sk); -- return; -- } -- -- if (bbr->round_start) -- bbr->lt_rtt_cnt++; /* count round trips in this interval */ -- if (bbr->lt_rtt_cnt < bbr_lt_intvl_min_rtts) -- return; /* sampling interval needs to be longer */ -- if (bbr->lt_rtt_cnt > 4 * bbr_lt_intvl_min_rtts) { -- bbr_reset_lt_bw_sampling(sk); /* interval is too long */ -- return; -- } -- -- /* End sampling interval when a packet is lost, so we estimate the -- * policer tokens were exhausted. Stopping the sampling before the -- * tokens are exhausted under-estimates the policed rate. -- */ -- if (!rs->losses) -- return; -- -- /* Calculate packets lost and delivered in sampling interval. */ -- lost = tp->lost - bbr->lt_last_lost; -- delivered = tp->delivered - bbr->lt_last_delivered; -- /* Is loss rate (lost/delivered) >= lt_loss_thresh? If not, wait. */ -- if (!delivered || (lost << BBR_SCALE) < bbr_lt_loss_thresh * delivered) -- return; -- -- /* Find average delivery rate in this sampling interval. */ -- t = div_u64(tp->delivered_mstamp, USEC_PER_MSEC) - bbr->lt_last_stamp; -- if ((s32)t < 1) -- return; /* interval is less than one ms, so wait */ -- /* Check if can multiply without overflow */ -- if (t >= ~0U / USEC_PER_MSEC) { -- bbr_reset_lt_bw_sampling(sk); /* interval too long; reset */ -- return; -- } -- t *= USEC_PER_MSEC; -- bw = (u64)delivered * BW_UNIT; -- do_div(bw, t); -- bbr_lt_bw_interval_done(sk, bw); --} -- --/* Estimate the bandwidth based on how fast packets are delivered */ --static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs) -+static u32 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); -- u64 bw; -+ u32 round_delivered = 0; - - bbr->round_start = 0; -- if (rs->delivered < 0 || rs->interval_us <= 0) -- return; /* Not a valid observation */ - - /* See if we've reached the next RTT */ -- if (!before(rs->prior_delivered, bbr->next_rtt_delivered)) { -+ if (rs->interval_us > 0 && -+ !before(rs->prior_delivered, bbr->next_rtt_delivered)) { -+ round_delivered = tp->delivered - bbr->next_rtt_delivered; - bbr->next_rtt_delivered = tp->delivered; -- bbr->rtt_cnt++; - bbr->round_start = 1; -- bbr->packet_conservation = 0; - } -+ return round_delivered; -+} - -- bbr_lt_bw_sampling(sk, rs); -+/* 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) -+{ -+ 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. - */ -- bw = div64_long((u64)rs->delivered * BW_UNIT, rs->interval_us); -- -- /* If this sample is application-limited, it is likely to have a very -- * low delivered count that represents application behavior rather than -- * the available network rate. Such a sample could drag down estimated -- * bw, causing needless slow-down. Thus, to continue to send at the -- * last measured network rate, we filter out app-limited samples unless -- * they describe the path bw at least as well as our bw model. -- * -- * So the goal during app-limited phase is to proceed with the best -- * network rate no matter how long. We automatically leave this -- * phase when app writes faster than the network can deliver :) -- */ -- if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) { -- /* Incorporate new sample into our max bw filter. */ -- minmax_running_max(&bbr->bw, bbr_bw_rtts, bbr->rtt_cnt, bw); -+ 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; - } - - /* Estimates the windowed max degree of ack aggregation. -@@ -812,7 +794,7 @@ static void bbr_update_bw(struct sock *sk, const struct rate_sample *rs) - * - * 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. -+ * 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) -@@ -820,15 +802,19 @@ static void bbr_update_ack_aggregation(struct sock *sk, - 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_param(sk, extra_acked_win_rtts); - -- if (!bbr_extra_acked_gain || rs->acked_sacked <= 0 || -+ if (!bbr_param(sk, extra_acked_gain) || rs->acked_sacked <= 0 || - rs->delivered < 0 || rs->interval_us <= 0) - return; - - if (bbr->round_start) { - bbr->extra_acked_win_rtts = min(0x1F, - bbr->extra_acked_win_rtts + 1); -- if (bbr->extra_acked_win_rtts >= bbr_extra_acked_win_rtts) { -+ if (!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; -@@ -862,49 +848,6 @@ static void bbr_update_ack_aggregation(struct sock *sk, - 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_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_full_bw_cnt; --} -- --/* If pipe is probably full, drain the queue and then enter steady-state. */ --static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs) --{ -- struct bbr *bbr = inet_csk_ca(sk); -- -- if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) { -- bbr->mode = BBR_DRAIN; /* drain queue we created */ -- tcp_sk(sk)->snd_ssthresh = -- bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); -- } /* 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)) -- bbr_reset_probe_bw_mode(sk); /* we estimate queue is drained */ --} -- - static void bbr_check_probe_rtt_done(struct sock *sk) - { - struct tcp_sock *tp = tcp_sk(sk); -@@ -914,9 +857,9 @@ static void bbr_check_probe_rtt_done(struct sock *sk) - after(tcp_jiffies32, bbr->probe_rtt_done_stamp))) - return; - -- bbr->min_rtt_stamp = tcp_jiffies32; /* wait a while until PROBE_RTT */ -+ bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */ - tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd)); -- bbr_reset_mode(sk); -+ bbr_exit_probe_rtt(sk); - } - - /* The goal of PROBE_RTT mode is to have BBR flows cooperatively and -@@ -942,23 +885,35 @@ static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs) - { - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); -- bool filter_expired; -+ bool probe_rtt_expired, min_rtt_expired; -+ u32 expire; - -- /* Track min RTT seen in the min_rtt_win_sec filter window: */ -- filter_expired = after(tcp_jiffies32, -- bbr->min_rtt_stamp + bbr_min_rtt_win_sec * HZ); -+ /* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */ -+ expire = bbr->probe_rtt_min_stamp + -+ msecs_to_jiffies(bbr_param(sk, probe_rtt_win_ms)); -+ probe_rtt_expired = after(tcp_jiffies32, expire); - if (rs->rtt_us >= 0 && -- (rs->rtt_us < bbr->min_rtt_us || -- (filter_expired && !rs->is_ack_delayed))) { -- bbr->min_rtt_us = rs->rtt_us; -- bbr->min_rtt_stamp = tcp_jiffies32; -+ (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_param(sk, 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_probe_rtt_mode_ms > 0 && filter_expired && -+ if (bbr_param(sk, 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) { -@@ -967,9 +922,9 @@ static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs) - (tp->delivered + tcp_packets_in_flight(tp)) ? : 1; - /* Maintain min packets in flight for max(200 ms, 1 round). */ - if (!bbr->probe_rtt_done_stamp && -- tcp_packets_in_flight(tp) <= bbr_cwnd_min_target) { -+ tcp_packets_in_flight(tp) <= bbr_probe_rtt_cwnd(sk)) { - bbr->probe_rtt_done_stamp = tcp_jiffies32 + -- msecs_to_jiffies(bbr_probe_rtt_mode_ms); -+ msecs_to_jiffies(bbr_param(sk, probe_rtt_mode_ms)); - bbr->probe_rtt_round_done = 0; - bbr->next_rtt_delivered = tp->delivered; - } else if (bbr->probe_rtt_done_stamp) { -@@ -990,18 +945,20 @@ static void bbr_update_gains(struct sock *sk) - - switch (bbr->mode) { - case BBR_STARTUP: -- bbr->pacing_gain = bbr_high_gain; -- bbr->cwnd_gain = bbr_high_gain; -+ bbr->pacing_gain = bbr_param(sk, startup_pacing_gain); -+ bbr->cwnd_gain = bbr_param(sk, startup_cwnd_gain); - break; - case BBR_DRAIN: -- bbr->pacing_gain = bbr_drain_gain; /* slow, to drain */ -- bbr->cwnd_gain = bbr_high_gain; /* keep cwnd */ -+ bbr->pacing_gain = bbr_param(sk, drain_gain); /* slow, to drain */ -+ bbr->cwnd_gain = bbr_param(sk, startup_cwnd_gain); /* keep cwnd */ - break; - case BBR_PROBE_BW: -- bbr->pacing_gain = (bbr->lt_use_bw ? -- BBR_UNIT : -- bbr_pacing_gain[bbr->cycle_idx]); -- bbr->cwnd_gain = bbr_cwnd_gain; -+ bbr->pacing_gain = bbr_pacing_gain[bbr->cycle_idx]; -+ bbr->cwnd_gain = bbr_param(sk, cwnd_gain); -+ if (bbr_param(sk, bw_probe_cwnd_gain) && -+ bbr->cycle_idx == BBR_BW_PROBE_UP) -+ bbr->cwnd_gain += -+ BBR_UNIT * bbr_param(sk, bw_probe_cwnd_gain) / 4; - break; - case BBR_PROBE_RTT: - bbr->pacing_gain = BBR_UNIT; -@@ -1013,144 +970,1387 @@ static void bbr_update_gains(struct sock *sk) - } - } - --static void bbr_update_model(struct sock *sk, const struct rate_sample *rs) -+__bpf_kfunc static u32 bbr_sndbuf_expand(struct sock *sk) - { -- bbr_update_bw(sk, rs); -- bbr_update_ack_aggregation(sk, rs); -- bbr_update_cycle_phase(sk, rs); -- bbr_check_full_bw_reached(sk, rs); -- bbr_check_drain(sk, rs); -- bbr_update_min_rtt(sk, rs); -- bbr_update_gains(sk); -+ /* Provision 3 * cwnd since BBR may slow-start even during recovery. */ -+ return 3; - } - --__bpf_kfunc static void bbr_main(struct sock *sk, u32 ack, int flag, const struct rate_sample *rs) -+/* Incorporate a new bw sample into the current window of our max filter. */ -+static void bbr_take_max_bw_sample(struct sock *sk, u32 bw) - { - struct bbr *bbr = inet_csk_ca(sk); -- u32 bw; -- -- bbr_update_model(sk, rs); - -- bw = bbr_bw(sk); -- bbr_set_pacing_rate(sk, bw, bbr->pacing_gain); -- bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain); -+ bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]); - } - --__bpf_kfunc static void bbr_init(struct sock *sk) -+/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */ -+static void bbr_advance_max_bw_filter(struct sock *sk) - { -- struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - -- bbr->prior_cwnd = 0; -- tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; -- bbr->rtt_cnt = 0; -- bbr->next_rtt_delivered = tp->delivered; -- bbr->prev_ca_state = TCP_CA_Open; -- bbr->packet_conservation = 0; -- -- bbr->probe_rtt_done_stamp = 0; -- bbr->probe_rtt_round_done = 0; -- bbr->min_rtt_us = tcp_min_rtt(tp); -- bbr->min_rtt_stamp = tcp_jiffies32; -- -- minmax_reset(&bbr->bw, bbr->rtt_cnt, 0); /* init max bw to 0 */ -+ 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; -+} - -- bbr->has_seen_rtt = 0; -- bbr_init_pacing_rate_from_rtt(sk); -+/* Reset the estimator for reaching full bandwidth based on bw plateau. */ -+static void bbr_reset_full_bw(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(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_reset_lt_bw_sampling(sk); -- bbr_reset_startup_mode(sk); -+ bbr->full_bw_now = 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; -+/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */ -+static u32 bbr_target_inflight(struct sock *sk) -+{ -+ u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT); - -- cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED); -+ return min(bdp, tcp_sk(sk)->snd_cwnd); - } - --__bpf_kfunc static u32 bbr_sndbuf_expand(struct sock *sk) -+static bool bbr_is_probing_bandwidth(struct sock *sk) - { -- /* Provision 3 * cwnd since BBR may slow-start even during recovery. */ -- return 3; -+ 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 bbr_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 bbr_handle_queue_too_high_in_startup(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 bdp; /* estimated BDP in packets, with quantization budget */ -+ -+ bbr->full_bw_reached = 1; -+ -+ bdp = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); -+ bbr->inflight_hi = max(bdp, bbr->inflight_latest); -+} -+ -+/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */ -+static void bbr_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_param(sk, full_ecn_cnt) || !bbr_param(sk, ecn_thresh)) -+ return; -+ -+ if (ce_ratio >= bbr_param(sk, ecn_thresh)) -+ bbr->startup_ecn_rounds++; -+ else -+ bbr->startup_ecn_rounds = 0; -+ -+ if (bbr->startup_ecn_rounds >= bbr_param(sk, full_ecn_cnt)) { -+ bbr_handle_queue_too_high_in_startup(sk); -+ return; -+ } -+} -+ -+/* Updates ecn_alpha and returns ce_ratio. -1 if not available. */ -+static int bbr_update_ecn_alpha(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct net *net = sock_net(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ s32 delivered, delivered_ce; -+ u64 alpha, ce_ratio; -+ u32 gain; -+ bool want_ecn_alpha; -+ -+ /* See if we should use ECN sender logic for this connection. */ -+ if (!bbr->ecn_eligible && bbr_can_use_ecn(sk) && -+ bbr_param(sk, ecn_factor) && -+ (bbr->min_rtt_us <= bbr_ecn_max_rtt_us || -+ !bbr_ecn_max_rtt_us)) -+ bbr->ecn_eligible = 1; -+ -+ /* Skip updating alpha only if not ECN-eligible and PLB is disabled. */ -+ want_ecn_alpha = (bbr->ecn_eligible || -+ (bbr_can_use_ecn(sk) && -+ READ_ONCE(net->ipv4.sysctl_tcp_plb_enabled))); -+ if (!want_ecn_alpha) -+ return -1; -+ -+ 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 -1; -+ -+ BUILD_BUG_ON(BBR_SCALE != TCP_PLB_SCALE); -+ ce_ratio = (u64)delivered_ce << BBR_SCALE; -+ do_div(ce_ratio, delivered); -+ -+ gain = bbr_param(sk, 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; -+ -+ bbr_check_ecn_too_high_in_startup(sk, ce_ratio); -+ return (int)ce_ratio; - } - --/* In theory BBR does not need to undo the cwnd since it does not -- * always reduce cwnd on losses (see bbr_main()). Keep it for now. -+/* Protective Load Balancing (PLB). PLB rehashes outgoing data (to a new IPv6 -+ * flow label) if it encounters sustained congestion in the form of ECN marks. - */ --__bpf_kfunc static u32 bbr_undo_cwnd(struct sock *sk) -+static void bbr_plb(struct sock *sk, const struct rate_sample *rs, int ce_ratio) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (bbr->round_start && ce_ratio >= 0) -+ tcp_plb_update_state(sk, &bbr->plb, ce_ratio); -+ -+ tcp_plb_check_rehash(sk, &bbr->plb); -+} -+ -+/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */ -+static void bbr_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 = tcp_snd_cwnd(tp) / growth_this_round; -+ cnt = max(cnt, 1U); -+ bbr->bw_probe_up_cnt = cnt; -+} -+ -+/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */ -+static void bbr_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 || tcp_snd_cwnd(tp) < bbr->inflight_hi) -+ 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->try_fast_path = 0; /* Need to update cwnd */ -+ } -+ -+ if (bbr->round_start) -+ bbr_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 bbr_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_param(sk, loss_thresh) >> -+ BBR_SCALE; -+ if (rs->lost > loss_thresh) { -+ return true; -+ } -+ } -+ -+ if (rs->delivered_ce > 0 && rs->delivered > 0 && -+ bbr->ecn_eligible && bbr_param(sk, ecn_thresh)) { -+ ecn_thresh = (u64)rs->delivered * bbr_param(sk, 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 bbr_inflight_hi_from_lost_skb(const struct sock *sk, -+ const struct rate_sample *rs, -+ const struct sk_buff *skb) -+{ -+ const struct tcp_sock *tp = tcp_sk(sk); -+ u32 loss_thresh = bbr_param(sk, 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 (inflight_prev < 0) { -+ WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious( -+ pcount, -+ TCP_SKB_CB(skb)->sacked, -+ rs->tx_in_flight), -+ "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_ONCE(lost_prev < 0, -+ "cwnd: %u ca: %d out: %u lost: %u pif: %u " -+ "tx_in_flight: %u tx.lost: %u tp->lost: %u rs->lost: %d " -+ "lost_prev: %d pcount: %d seq: %u end_seq: %u reneg: %u", -+ tcp_snd_cwnd(tp), inet_csk(sk)->icsk_ca_state, -+ tp->packets_out, tp->lost_out, tcp_packets_in_flight(tp), -+ rs->tx_in_flight, TCP_SKB_CB(skb)->tx.lost, tp->lost, -+ rs->lost, lost_prev, pcount, -+ TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, -+ tp->is_sack_reneg)) -+ 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 bbr_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_param(sk, inflight_headroom); -+ headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE; -+ headroom = max(headroom, 1U); -+ return max_t(s32, bbr->inflight_hi - headroom, -+ bbr_param(sk, 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 bbr_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 = bbr_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_param(sk, cwnd_min_target)); -+ tcp_snd_cwnd_set(tp, min(cap, tcp_snd_cwnd(tp))); -+} -+ -+/* How should we multiplicatively cut bw or inflight limits based on ECN? */ -+static u32 bbr_ecn_cut(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ return BBR_UNIT - -+ ((bbr->ecn_alpha * bbr_param(sk, ecn_factor)) >> BBR_SCALE); -+} -+ -+/* Init lower bounds if have not inited yet. */ -+static void bbr_init_lower_bounds(struct sock *sk, bool init_bw) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ if (init_bw && bbr->bw_lo == ~0U) -+ bbr->bw_lo = bbr_max_bw(sk); -+ if (bbr->inflight_lo == ~0U) -+ bbr->inflight_lo = tcp_snd_cwnd(tp); -+} -+ -+/* Reduce bw and inflight to (1 - beta). */ -+static void bbr_loss_lower_bounds(struct sock *sk, u32 *bw, u32 *inflight) -+{ -+ struct bbr* bbr = inet_csk_ca(sk); -+ u32 loss_cut = BBR_UNIT - bbr_param(sk, beta); -+ -+ *bw = max_t(u32, bbr->bw_latest, -+ (u64)bbr->bw_lo * loss_cut >> BBR_SCALE); -+ *inflight = max_t(u32, bbr->inflight_latest, -+ (u64)bbr->inflight_lo * loss_cut >> BBR_SCALE); -+} -+ -+/* Reduce inflight to (1 - alpha*ecn_factor). */ -+static void bbr_ecn_lower_bounds(struct sock *sk, u32 *inflight) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 ecn_cut = bbr_ecn_cut(sk); -+ -+ *inflight = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE; -+} -+ -+/* 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 bbr_adapt_lower_bounds(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 ecn_inflight_lo = ~0U; -+ -+ /* We only use lower-bound estimates when not probing bw. -+ * When probing we need to push inflight higher to probe bw. -+ */ -+ if (bbr_is_probing_bandwidth(sk)) -+ return; -+ -+ /* ECN response. */ -+ if (bbr->ecn_in_round && bbr_param(sk, ecn_factor)) { -+ bbr_init_lower_bounds(sk, false); -+ bbr_ecn_lower_bounds(sk, &ecn_inflight_lo); -+ } -+ -+ /* Loss response. */ -+ if (bbr->loss_in_round) { -+ bbr_init_lower_bounds(sk, true); -+ bbr_loss_lower_bounds(sk, &bbr->bw_lo, &bbr->inflight_lo); -+ } -+ -+ /* Adjust to the lower of the levels implied by loss/ECN. */ -+ bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo); -+ bbr->bw_lo = max(1U, bbr->bw_lo); -+} -+ -+/* Reset any short-term lower-bound adaptation to congestion, so that we can -+ * push our inflight up. -+ */ -+static void bbr_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 bbr_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; -+} -+ -+static void bbr_exit_loss_recovery(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp), bbr->prior_cwnd)); -+ bbr->try_fast_path = 0; /* bound cwnd using latest model */ -+} -+ -+/* Update rate and volume of delivered data from latest round trip. */ -+static void bbr_update_latest_delivery_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); -+ -+ bbr->loss_round_start = 0; -+ if (rs->interval_us <= 0 || !rs->acked_sacked) -+ return; /* Not a valid observation */ -+ -+ 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)) { -+ bbr->loss_round_delivered = tp->delivered; -+ bbr->loss_round_start = 1; /* mark start of new round trip */ -+ } -+} -+ -+/* Once per round, reset filter for latest rate and volume of delivered data. */ -+static void bbr_advance_latest_delivery_signals( -+ struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ /* If ACK matches a TLP retransmit, persist the filter. If we detect -+ * that a TLP retransmit plugged a tail loss, we'll want to remember -+ * how much data the path delivered before the tail loss. -+ */ -+ if (bbr->loss_round_start && !rs->is_acking_tlp_retrans_seq) { -+ bbr->bw_latest = ctx->sample_bw; -+ bbr->inflight_latest = rs->delivered; -+ } -+} -+ -+/* 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 bbr_update_congestion_signals( -+ struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) - { - struct bbr *bbr = inet_csk_ca(sk); -+ u64 bw; -+ -+ if (rs->interval_us <= 0 || !rs->acked_sacked) -+ return; /* Not a valid observation */ -+ bw = ctx->sample_bw; - -- bbr->full_bw = 0; /* spurious slow-down; reset full pipe detection */ -+ if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) -+ bbr_take_max_bw_sample(sk, bw); -+ -+ bbr->loss_in_round |= (rs->losses > 0); -+ -+ if (!bbr->loss_round_start) -+ return; /* skip the per-round-trip updates */ -+ /* Now do per-round-trip updates. */ -+ bbr_adapt_lower_bounds(sk, rs); -+ -+ bbr->loss_in_round = 0; -+ bbr->ecn_in_round = 0; -+} -+ -+/* 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 bbr_is_reno_coexistence_probe_time(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 rounds; -+ -+ /* Random loss can shave some small percentage off of our inflight -+ * in each round. To survive this, flows need robust periodic probes. -+ */ -+ rounds = min_t(u32, bbr_param(sk, bw_probe_max_rounds), bbr_target_inflight(sk)); -+ 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 bbr_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_param(sk, bw_probe_rand_rounds)); -+ /* Decide the random wall clock bound for wait until probe: */ -+ bbr->probe_wait_us = bbr_param(sk, bw_probe_base_us) + -+ get_random_u32_below(bbr_param(sk, bw_probe_rand_us)); -+} -+ -+static void bbr_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 bbr_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); -+ -+ bbr_reset_lower_bounds(sk); -+ 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; -+ bbr_set_cycle_idx(sk, BBR_BW_PROBE_REFILL); -+} -+ -+/* Now probe max deliverable data rate and volume. */ -+static void bbr_start_bw_probe_up(struct sock *sk, struct bbr_context *ctx) -+{ -+ 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; -+ bbr_reset_full_bw(sk); -+ bbr->full_bw = ctx->sample_bw; -+ bbr_set_cycle_idx(sk, BBR_BW_PROBE_UP); -+ bbr_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 bbr_start_bw_probe_down(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr_reset_congestion_signals(sk); -+ bbr->bw_probe_up_cnt = ~0U; /* not growing inflight_hi any more */ -+ bbr_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; -+ bbr_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 bbr_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); -+ -+ bbr_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 bbr_handle_inflight_too_high(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ const u32 beta = bbr_param(sk, beta); -+ -+ bbr->prev_probe_too_high = 1; -+ bbr->bw_probe_samples = 0; /* only react once per probe */ -+ /* 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)bbr_target_inflight(sk) * -+ (BBR_UNIT - beta) >> BBR_SCALE); -+ } -+ if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) -+ bbr_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 bbr_adapt_upper_bounds(struct sock *sk, -+ const struct rate_sample *rs, -+ struct bbr_context *ctx) -+{ -+ 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) -+ bbr_advance_max_bw_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_start_bw_probe_refill(sk, 0); -+ return true; /* yes, decided state transition */ -+ } -+ } -+ if (bbr_is_inflight_too_high(sk, rs)) { -+ if (bbr->bw_probe_samples) /* sample is from bw probing? */ -+ bbr_handle_inflight_too_high(sk, rs); -+ } else { -+ /* Loss/ECN rate is declared safe. Adjust upper bound upward. */ -+ -+ if (bbr->inflight_hi == ~0U) -+ return false; /* no excess queue signals yet */ -+ -+ /* To be resilient to random loss, we must raise bw/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; -+ } -+ -+ if (bbr->mode == BBR_PROBE_BW && -+ bbr->cycle_idx == BBR_BW_PROBE_UP) -+ bbr_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 bbr_check_time_to_probe_bw(struct sock *sk, -+ const struct rate_sample *rs) -+{ -+ 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 cross-traffic has ceased and freed up bw). -+ */ -+ if (bbr_param(sk, ecn_reprobe_gain) && bbr->ecn_eligible && -+ bbr->ecn_in_cycle && !bbr->loss_in_cycle && -+ inet_csk(sk)->icsk_ca_state == TCP_CA_Open) { -+ /* Calculate n so that when bbr_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_param(sk, ecn_reprobe_gain)) >> BBR_SCALE)); -+ bbr_start_bw_probe_refill(sk, n); -+ return true; -+ } -+ -+ if (bbr_has_elapsed_in_phase(sk, bbr->probe_wait_us) || -+ bbr_is_reno_coexistence_probe_time(sk)) { -+ bbr_start_bw_probe_refill(sk, 0); -+ return true; -+ } -+ return false; -+} -+ -+/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */ -+static bool bbr_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw) -+{ -+ /* Always need to pull inflight down to leave headroom in queue. */ -+ if (inflight > bbr_inflight_with_headroom(sk)) -+ return false; -+ -+ return inflight <= bbr_inflight(sk, bw, BBR_UNIT); -+} -+ -+/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */ -+static void bbr_update_cycle_phase(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); -+ bool is_bw_probe_done = false; -+ u32 inflight, bw; -+ -+ if (!bbr_full_bw_reached(sk)) -+ return; -+ -+ /* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */ -+ if (bbr_adapt_upper_bounds(sk, rs, ctx)) -+ 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 (bbr_check_time_to_probe_bw(sk, rs)) -+ 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; -+ bbr_start_bw_probe_up(sk, ctx); -+ } -+ 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. -+ * (2) If inflight_hi has not limited bandwidth growth recently, and -+ * yet delivered bandwidth has not increased much recently -+ * (bbr->full_bw_now). -+ * (3) Loss filter says loss rate is "too high". -+ * (4) ECN filter says ECN mark rate is "too high". -+ * -+ * (1) (2) checked here, (3) (4) 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_bw_probe_done = true; -+ } else { -+ if (tp->is_cwnd_limited && -+ tcp_snd_cwnd(tp) >= bbr->inflight_hi) { -+ /* inflight_hi is limiting bw growth */ -+ bbr_reset_full_bw(sk); -+ bbr->full_bw = ctx->sample_bw; -+ } else if (bbr->full_bw_now) { -+ /* Plateau in estimated bw. Pipe looks full. */ -+ is_bw_probe_done = true; -+ } -+ } -+ if (is_bw_probe_done) { -+ bbr->prev_probe_too_high = 0; /* no loss/ECN (yet) */ -+ bbr_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 (bbr_check_time_to_probe_bw(sk, rs)) -+ return; /* already decided state transition */ -+ if (bbr_check_time_to_cruise(sk, inflight, bw)) -+ bbr_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 bbr_exit_probe_rtt(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr_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. -+ */ -+ bbr_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. -+ */ -+ bbr_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 bbr_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_param(sk, full_loss_cnt) && bbr->loss_round_start && -+ inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery && -+ bbr->loss_events_in_round >= bbr_param(sk, full_loss_cnt) && -+ bbr_is_inflight_too_high(sk, rs)) { -+ bbr_handle_queue_too_high_in_startup(sk); -+ return; -+ } -+ if (bbr->loss_round_start) -+ bbr->loss_events_in_round = 0; -+} -+ -+/* Estimate when the pipe is full, using the change in delivery rate: BBR -+ * estimates bw probing 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_context *ctx) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ u32 bw_thresh, full_cnt, thresh; -+ -+ if (bbr->full_bw_now || rs->is_app_limited) -+ return; -+ -+ thresh = bbr_param(sk, full_bw_thresh); -+ full_cnt = bbr_param(sk, full_bw_cnt); -+ bw_thresh = (u64)bbr->full_bw * thresh >> BBR_SCALE; -+ if (ctx->sample_bw >= bw_thresh) { -+ bbr_reset_full_bw(sk); -+ bbr->full_bw = ctx->sample_bw; -+ return; -+ } -+ if (!bbr->round_start) -+ return; -+ ++bbr->full_bw_cnt; -+ bbr->full_bw_now = bbr->full_bw_cnt >= full_cnt; -+ bbr->full_bw_reached |= bbr->full_bw_now; -+} -+ -+/* If pipe is probably full, drain the queue and then enter steady-state. */ -+static void bbr_check_drain(struct sock *sk, const struct rate_sample *rs, -+ struct bbr_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 */ -+ /* Set ssthresh to export purely for monitoring, to signal -+ * completion of initial STARTUP by setting to a non- -+ * TCP_INFINITE_SSTHRESH value (ssthresh is not used by BBR). -+ */ -+ tcp_sk(sk)->snd_ssthresh = -+ bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); -+ bbr_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)) { -+ bbr->mode = BBR_PROBE_BW; -+ bbr_start_bw_probe_down(sk); -+ } -+} -+ -+static void bbr_update_model(struct sock *sk, const struct rate_sample *rs, -+ struct bbr_context *ctx) -+{ -+ bbr_update_congestion_signals(sk, rs, ctx); -+ bbr_update_ack_aggregation(sk, rs); -+ bbr_check_loss_too_high_in_startup(sk, rs); -+ bbr_check_full_bw_reached(sk, rs, ctx); -+ bbr_check_drain(sk, rs, ctx); -+ bbr_update_cycle_phase(sk, rs, ctx); -+ 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 bbr_run_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_param(sk, 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; -+ bbr_check_drain(sk, rs, ctx); -+ bbr_update_cycle_phase(sk, rs, ctx); -+ 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; -+} -+ -+__bpf_kfunc static void bbr_main(struct sock *sk, u32 ack, int flag, 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, round_delivered; -+ int ce_ratio = -1; -+ -+ round_delivered = bbr_update_round_start(sk, rs, &ctx); -+ if (bbr->round_start) { -+ bbr->rounds_since_probe = -+ min_t(s32, bbr->rounds_since_probe + 1, 0xFF); -+ ce_ratio = bbr_update_ecn_alpha(sk); -+ } -+ bbr_plb(sk, rs, ce_ratio); -+ -+ bbr->ecn_in_round |= (bbr->ecn_eligible && rs->is_ece); -+ bbr_calculate_bw_sample(sk, rs, &ctx); -+ bbr_update_latest_delivery_signals(sk, rs, &ctx); -+ -+ if (bbr_run_fast_path(sk, &update_model, rs, &ctx)) -+ goto out; -+ -+ if (update_model) -+ bbr_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, -+ tcp_snd_cwnd(tp), &ctx); -+ bbr_bound_cwnd_for_inflight_model(sk); -+ -+out: -+ bbr_advance_latest_delivery_signals(sk, rs, &ctx); -+ 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; -+} -+ -+__bpf_kfunc static void bbr_init(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr->initialized = 1; -+ -+ bbr->init_cwnd = min(0x7FU, tcp_snd_cwnd(tp)); -+ bbr->prior_cwnd = tp->prior_cwnd; -+ tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; -+ bbr->next_rtt_delivered = tp->delivered; -+ bbr->prev_ca_state = TCP_CA_Open; -+ -+ 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_reset_lt_bw_sampling(sk); -- return tcp_snd_cwnd(tcp_sk(sk)); -+ bbr->cycle_mstamp = 0; -+ bbr->cycle_idx = 0; -+ -+ bbr_reset_startup_mode(sk); -+ -+ bbr->ack_epoch_mstamp = tp->tcp_mstamp; -+ bbr->ack_epoch_acked = 0; -+ bbr->extra_acked_win_rtts = 0; -+ bbr->extra_acked_win_idx = 0; -+ bbr->extra_acked[0] = 0; -+ bbr->extra_acked[1] = 0; -+ -+ 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); -+ -+ /* 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; -+ bbr_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_reset_full_bw(sk); -+ 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_param(sk, ecn_alpha_init); -+ bbr->alpha_last_delivered = 0; -+ bbr->alpha_last_delivered_ce = 0; -+ bbr->plb.pause_until = 0; -+ -+ tp->fast_ack_mode = bbr_fast_ack_mode ? 1 : 0; -+ -+ if (bbr_can_use_ecn(sk)) -+ tp->ecn_flags |= TCP_ECN_ECT_PERMANENT; -+} -+ -+/* BBR marks the current round trip as a loss round. */ -+static void bbr_note_loss(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ /* Capture "current" data over the full round trip of loss, to -+ * have a better chance of observing 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; - } - --/* Entering loss recovery, so save cwnd for when we exit or undo recovery. */ -+/* Core TCP stack informs us that the given skb was just marked lost. */ -+__bpf_kfunc static void bbr_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 = {}; -+ -+ bbr_note_loss(sk); -+ -+ 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. -+ */ -+ 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 (bbr_is_inflight_too_high(sk, &rs)) { -+ rs.tx_in_flight = bbr_inflight_hi_from_lost_skb(sk, &rs, skb); -+ bbr_handle_inflight_too_high(sk, &rs); -+ } -+} -+ -+static void bbr_run_loss_probe_recovery(struct sock *sk) -+{ -+ struct tcp_sock *tp = tcp_sk(sk); -+ struct bbr *bbr = inet_csk_ca(sk); -+ struct rate_sample rs = {0}; -+ -+ bbr_note_loss(sk); -+ -+ if (!bbr->bw_probe_samples) -+ return; /* not sent while probing for bandwidth */ -+ /* We are probing for bandwidth. Construct a rate sample that -+ * estimates what happened in the flight leading up to this -+ * loss, then see if the loss rate went too high. -+ */ -+ rs.lost = 1; /* TLP probe repaired loss of a single segment */ -+ rs.tx_in_flight = bbr->inflight_latest + rs.lost; -+ rs.is_app_limited = tp->tlp_orig_data_app_limited; -+ if (bbr_is_inflight_too_high(sk, &rs)) -+ bbr_handle_inflight_too_high(sk, &rs); -+} -+ -+/* Revert short-term model if current loss recovery event was spurious. */ -+__bpf_kfunc static u32 bbr_undo_cwnd(struct sock *sk) -+{ -+ struct bbr *bbr = inet_csk_ca(sk); -+ -+ bbr_reset_full_bw(sk); /* spurious slow-down; reset full bw detector */ -+ bbr->loss_in_round = 0; -+ -+ /* 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); -+ bbr->try_fast_path = 0; /* take slow path to set proper cwnd, pacing */ -+ return bbr->prior_cwnd; -+} -+ -+/* Entering loss recovery, so save state for when we undo recovery. */ - __bpf_kfunc static u32 bbr_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_bbr_phase bbr_get_phase(struct bbr *bbr) -+{ -+ switch (bbr->mode) { -+ case BBR_STARTUP: -+ return BBR_PHASE_STARTUP; -+ case BBR_DRAIN: -+ return BBR_PHASE_DRAIN; -+ case BBR_PROBE_BW: -+ break; -+ case BBR_PROBE_RTT: -+ return BBR_PHASE_PROBE_RTT; -+ default: -+ return BBR_PHASE_INVALID; -+ } -+ switch (bbr->cycle_idx) { -+ case BBR_BW_PROBE_UP: -+ return BBR_PHASE_PROBE_BW_UP; -+ case BBR_BW_PROBE_DOWN: -+ return BBR_PHASE_PROBE_BW_DOWN; -+ case BBR_BW_PROBE_CRUISE: -+ return BBR_PHASE_PROBE_BW_CRUISE; -+ case BBR_BW_PROBE_REFILL: -+ return BBR_PHASE_PROBE_BW_REFILL; -+ default: -+ return BBR_PHASE_INVALID; -+ } -+} -+ - static size_t bbr_get_info(struct sock *sk, u32 ext, int *attr, -- union tcp_cc_info *info) -+ union tcp_cc_info *info) - { - if (ext & (1 << (INET_DIAG_BBRINFO - 1)) || - ext & (1 << (INET_DIAG_VEGASINFO - 1))) { -- struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); -- u64 bw = bbr_bw(sk); -- -- bw = bw * tp->mss_cache * USEC_PER_SEC >> BW_SCALE; -- memset(&info->bbr, 0, sizeof(info->bbr)); -- info->bbr.bbr_bw_lo = (u32)bw; -- info->bbr.bbr_bw_hi = (u32)(bw >> 32); -- info->bbr.bbr_min_rtt = bbr->min_rtt_us; -- info->bbr.bbr_pacing_gain = bbr->pacing_gain; -- info->bbr.bbr_cwnd_gain = bbr->cwnd_gain; -+ 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); -+ struct tcp_bbr_info *bbr_info = &info->bbr; -+ -+ memset(bbr_info, 0, sizeof(*bbr_info)); -+ bbr_info->bbr_bw_lo = (u32)bw; -+ bbr_info->bbr_bw_hi = (u32)(bw >> 32); -+ bbr_info->bbr_min_rtt = bbr->min_rtt_us; -+ bbr_info->bbr_pacing_gain = bbr->pacing_gain; -+ bbr_info->bbr_cwnd_gain = bbr->cwnd_gain; -+ bbr_info->bbr_bw_hi_lsb = (u32)bw_hi; -+ bbr_info->bbr_bw_hi_msb = (u32)(bw_hi >> 32); -+ bbr_info->bbr_bw_lo_lsb = (u32)bw_lo; -+ bbr_info->bbr_bw_lo_msb = (u32)(bw_lo >> 32); -+ bbr_info->bbr_mode = bbr->mode; -+ bbr_info->bbr_phase = (__u8)bbr_get_phase(bbr); -+ bbr_info->bbr_version = (__u8)BBR_VERSION; -+ bbr_info->bbr_inflight_lo = bbr->inflight_lo; -+ bbr_info->bbr_inflight_hi = bbr->inflight_hi; -+ bbr_info->bbr_extra_acked = bbr_extra_acked(sk); - *attr = INET_DIAG_BBRINFO; -- return sizeof(info->bbr); -+ return sizeof(*bbr_info); - } - return 0; - } - - __bpf_kfunc static void bbr_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 }; - - bbr->prev_ca_state = TCP_CA_Loss; -- bbr->full_bw = 0; -- bbr->round_start = 1; /* treat RTO like end of a round */ -- bbr_lt_bw_sampling(sk, &rs); -+ tcp_plb_update_state_upon_rto(sk, &bbr->plb); -+ /* The tcp_write_timeout() call to sk_rethink_txhash() likely -+ * repathed this flow, so re-learn the min network RTT on the -+ * new path: -+ */ -+ bbr_reset_full_bw(sk); -+ if (!bbr_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(tcp_snd_cwnd(tp), bbr->prior_cwnd); -+ } -+ } else if (bbr->prev_ca_state == TCP_CA_Loss && -+ new_state != TCP_CA_Loss) { -+ bbr_exit_loss_recovery(sk); - } - } - -+ - static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = { -- .flags = TCP_CONG_NON_RESTRICTED, -+ .flags = TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS, - .name = "bbr", - .owner = THIS_MODULE, - .init = bbr_init, - .cong_control = bbr_main, - .sndbuf_expand = bbr_sndbuf_expand, -+ .skb_marked_lost = bbr_skb_marked_lost, - .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, - }; -@@ -1159,10 +2359,11 @@ BTF_KFUNCS_START(tcp_bbr_check_kfunc_ids) - BTF_ID_FLAGS(func, bbr_init) - BTF_ID_FLAGS(func, bbr_main) - BTF_ID_FLAGS(func, bbr_sndbuf_expand) -+BTF_ID_FLAGS(func, bbr_skb_marked_lost) - BTF_ID_FLAGS(func, bbr_undo_cwnd) - BTF_ID_FLAGS(func, bbr_cwnd_event) - BTF_ID_FLAGS(func, bbr_ssthresh) --BTF_ID_FLAGS(func, bbr_min_tso_segs) -+BTF_ID_FLAGS(func, bbr_tso_segs) - BTF_ID_FLAGS(func, bbr_set_state) - BTF_KFUNCS_END(tcp_bbr_check_kfunc_ids) - -@@ -1195,5 +2396,12 @@ 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_AUTHOR("David Morley <morleyd@google.com>"); -+ - MODULE_LICENSE("Dual BSD/GPL"); - MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)"); -+MODULE_VERSION(__stringify(BBR_VERSION)); -diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c -index 28ffcfbeef14..7b13915ba288 100644 ---- a/net/ipv4/tcp_cong.c -+++ b/net/ipv4/tcp_cong.c -@@ -237,6 +237,7 @@ 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 570e87ad9a56..c539ac50f7a6 100644 ---- a/net/ipv4/tcp_input.c -+++ b/net/ipv4/tcp_input.c -@@ -365,7 +365,7 @@ 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)) { -@@ -376,7 +376,7 @@ 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; -@@ -1115,7 +1115,12 @@ 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) -@@ -1496,6 +1501,17 @@ 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 -@@ -3790,7 +3806,8 @@ static void tcp_replace_ts_recent(struct tcp_sock *tp, u32 seq) - /* This routine deals with acks during a TLP episode and ends an episode by - * resetting tlp_high_seq. Ref: TLP algorithm in draft-ietf-tcpm-rack - */ --static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag) -+static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag, -+ struct rate_sample *rs) - { - struct tcp_sock *tp = tcp_sk(sk); - -@@ -3807,6 +3824,7 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag) - /* ACK advances: there was a loss, so reduce cwnd. Reset - * tlp_high_seq in tcp_init_cwnd_reduction() - */ -+ tcp_ca_event(sk, CA_EVENT_TLP_RECOVERY); - tcp_init_cwnd_reduction(sk); - tcp_set_ca_state(sk, TCP_CA_CWR); - tcp_end_cwnd_reduction(sk); -@@ -3817,6 +3835,11 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag) - FLAG_NOT_DUP | FLAG_DATA_SACKED))) { - /* Pure dupack: original and TLP probe arrived; no loss */ - tp->tlp_high_seq = 0; -+ } else { -+ /* This ACK matches a TLP retransmit. We cannot yet tell if -+ * this ACK is for the original or the TLP retransmit. -+ */ -+ rs->is_acking_tlp_retrans_seq = 1; - } - } - -@@ -3925,6 +3948,7 @@ 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. -@@ -3999,7 +4023,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) - tcp_rack_update_reo_wnd(sk, &rs); - - if (tp->tlp_high_seq) -- tcp_process_tlp_ack(sk, ack, flag); -+ tcp_process_tlp_ack(sk, ack, flag, &rs); - - if (tcp_ack_is_dubious(sk, flag)) { - if (!(flag & (FLAG_SND_UNA_ADVANCED | -@@ -4023,6 +4047,7 @@ 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); -@@ -4042,7 +4067,7 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag) - tcp_ack_probe(sk); - - if (tp->tlp_high_seq) -- tcp_process_tlp_ack(sk, ack, flag); -+ tcp_process_tlp_ack(sk, ack, flag, &rs); - return 1; - - old_ack: -@@ -5714,13 +5739,14 @@ 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_minisocks.c b/net/ipv4/tcp_minisocks.c -index 0fbebf6266e9..6eb1d369c584 100644 ---- a/net/ipv4/tcp_minisocks.c -+++ b/net/ipv4/tcp_minisocks.c -@@ -460,6 +460,8 @@ void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst) - u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); - bool ca_got_dst = false; - -+ tcp_set_ecn_low_from_dst(sk, dst); -+ - if (ca_key != TCP_CA_UNSPEC) { - const struct tcp_congestion_ops *ca; - -diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c -index 95618d0e78e4..3f4bdd2b6476 100644 ---- a/net/ipv4/tcp_output.c -+++ b/net/ipv4/tcp_output.c -@@ -336,10 +336,9 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) - bool bpf_needs_ecn = tcp_bpf_ca_needs_ecn(sk); - bool use_ecn = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_ecn) == 1 || - tcp_ca_needs_ecn(sk) || bpf_needs_ecn; -+ const struct dst_entry *dst = __sk_dst_get(sk); - - if (!use_ecn) { -- const struct dst_entry *dst = __sk_dst_get(sk); -- - if (dst && dst_feature(dst, RTAX_FEATURE_ECN)) - use_ecn = true; - } -@@ -351,6 +350,9 @@ static void tcp_ecn_send_syn(struct sock *sk, struct sk_buff *skb) - tp->ecn_flags = TCP_ECN_OK; - if (tcp_ca_needs_ecn(sk) || bpf_needs_ecn) - INET_ECN_xmit(sk); -+ -+ if (dst) -+ tcp_set_ecn_low_from_dst(sk, dst); - } - } - -@@ -388,7 +390,8 @@ 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); - } -@@ -1601,7 +1604,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, - { - 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; -@@ -1676,6 +1679,30 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, - - if (diff) - tcp_adjust_pcount(sk, skb, diff); -+ -+ inflight_prev = TCP_SKB_CB(skb)->tx.in_flight - old_factor; -+ if (inflight_prev < 0) { -+ WARN_ONCE(tcp_skb_tx_in_flight_is_suspicious( -+ old_factor, -+ TCP_SKB_CB(skb)->sacked, -+ TCP_SKB_CB(skb)->tx.in_flight), -+ "inconsistent: tx.in_flight: %u " -+ "old_factor: %d mss: %u sacked: %u " -+ "1st pcount: %d 2nd pcount: %d " -+ "1st len: %u 2nd len: %u ", -+ TCP_SKB_CB(skb)->tx.in_flight, old_factor, -+ mss_now, TCP_SKB_CB(skb)->sacked, -+ tcp_skb_pcount(skb), tcp_skb_pcount(buff), -+ skb->len, buff->len); -+ inflight_prev = 0; -+ } -+ /* Set 1st tx.in_flight as if 1st were sent by itself: */ -+ TCP_SKB_CB(skb)->tx.in_flight = inflight_prev + -+ tcp_skb_pcount(skb); -+ /* Set 2nd tx.in_flight with new 1st and 2nd pcounts: */ -+ TCP_SKB_CB(buff)->tx.in_flight = inflight_prev + -+ tcp_skb_pcount(skb) + -+ tcp_skb_pcount(buff); - } - - /* Link BUFF into the send queue. */ -@@ -2033,13 +2060,12 @@ 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, -+ sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs); - return min_t(u32, tso_segs, sk->sk_gso_max_segs); - } - -@@ -2767,6 +2793,7 @@ 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 */ - } - -@@ -2981,6 +3008,7 @@ void tcp_send_loss_probe(struct sock *sk) - if (WARN_ON(!skb || !tcp_skb_pcount(skb))) - goto rearm_timer; - -+ tp->tlp_orig_data_app_limited = TCP_SKB_CB(skb)->tx.is_app_limited; - if (__tcp_retransmit_skb(sk, skb, 1)) - goto rearm_timer; - -diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c -index a8f6d9d06f2e..8737f2134648 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->tx_in_flight = scb->tx.in_flight; - rs->last_end_seq = scb->end_seq; - - /* 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 4d40615dc8fc..f27941201ef2 100644 ---- a/net/ipv4/tcp_timer.c -+++ b/net/ipv4/tcp_timer.c -@@ -689,6 +689,7 @@ 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; - --- -2.46.0.rc1 - |