diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index a8119e327dda5..0fa3c2530cf97 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -1085,64 +1085,6 @@ tcp_child_ehash_entries - INTEGER Default: 0 -tcp_plb_enabled - BOOLEAN - If set, TCP PLB (Protective Load Balancing) is enabled. PLB is - described in the following paper: - https://doi.org/10.1145/3544216.3544226. Based on PLB parameters, - upon sensing sustained congestion, TCP triggers a change in - flow label field for outgoing IPv6 packets. A change in flow label - field potentially changes the path of outgoing packets for switches - that use ECMP/WCMP for routing. - - Default: 0 - -tcp_plb_cong_thresh - INTEGER - Fraction of packets marked with congestion over a round (RTT) to - tag that round as congested. This is referred to as K in the PLB paper: - https://doi.org/10.1145/3544216.3544226. - - The 0-1 fraction range is mapped to 0-256 range to avoid floating - point operations. For example, 128 means that if at least 50% of - the packets in a round were marked as congested then the round - will be tagged as congested. - - Possible Values: 0 - 256 - - Default: 128 - -tcp_plb_idle_rehash_rounds - INTEGER - Number of consecutive congested rounds (RTT) seen after which - a rehash can be performed, given there are no packets in flight. - This is referred to as M in PLB paper: - https://doi.org/10.1145/3544216.3544226. - - Possible Values: 0 - 31 - - Default: 3 - -tcp_plb_rehash_rounds - INTEGER - Number of consecutive congested rounds (RTT) seen after which - a forced rehash can be performed. Be careful when setting this - parameter, as a small value increases the risk of retransmissions. - This is referred to as N in PLB paper: - https://doi.org/10.1145/3544216.3544226. - - Possible Values: 0 - 31 - - Default: 12 - -tcp_plb_suspend_rto_sec - INTEGER - Time, in seconds, to suspend PLB in event of an RTO. In order to avoid - having PLB repath onto a connectivity "black hole", after an RTO a TCP - connection suspends PLB repathing for a random duration between 1x and - 2x of this parameter. Randomness is added to avoid concurrent rehashing - of multiple TCP connections. This should be set corresponding to the - amount of time it takes to repair a failed link. - - Possible Values: 0 - 255 - - Default: 60 - UDP variables ============= diff --git a/include/linux/tcp.h b/include/linux/tcp.h index efc517dfe039d..9cd289ad3f5b5 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -255,8 +255,7 @@ struct tcp_sock { u8 compressed_ack; u8 dup_ack_counter:2, tlp_retrans:1, /* TLP is a retransmission */ - fast_ack_mode:2, /* which fast ack mode ? */ - unused:3; + unused:5; u32 chrono_start; /* Start time in jiffies of a TCP chrono */ u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */ u8 chrono_type:2, /* current chronograph type */ @@ -450,9 +449,6 @@ struct tcp_sock { */ struct request_sock __rcu *fastopen_rsk; struct saved_syn *saved_syn; - -/* Rerouting information */ - u16 ecn_rehash; /* PLB triggered rehash attempts */ }; enum tsq_enum { diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h index 273610e431967..c2b15f7e55161 100644 --- a/include/net/inet_connection_sock.h +++ b/include/net/inet_connection_sock.h @@ -135,8 +135,7 @@ struct inet_connection_sock { u32 icsk_probes_tstamp; u32 icsk_user_timeout; -/* XXX inflated by temporary internal debugging info */ - u64 icsk_ca_priv[224 / sizeof(u64)]; + u64 icsk_ca_priv[104 / sizeof(u64)]; #define ICSK_CA_PRIV_SIZE sizeof_field(struct inet_connection_sock, icsk_ca_priv) }; diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index 69eae05120418..2d8ca77311462 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -183,11 +183,6 @@ struct netns_ipv4 { unsigned long tfo_active_disable_stamp; u32 tcp_challenge_timestamp; u32 tcp_challenge_count; - u8 sysctl_tcp_plb_enabled; - int sysctl_tcp_plb_cong_thresh; - u8 sysctl_tcp_plb_idle_rehash_rounds; - u8 sysctl_tcp_plb_rehash_rounds; - u8 sysctl_tcp_plb_suspend_rto_sec; int sysctl_udp_wmem_min; int sysctl_udp_rmem_min; diff --git a/include/net/tcp.h b/include/net/tcp.h index 43648cbddd45f..e9c8f88f47696 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -375,7 +375,6 @@ static inline void tcp_dec_quickack_mode(struct sock *sk, #define TCP_ECN_QUEUE_CWR 2 #define TCP_ECN_DEMAND_CWR 4 #define TCP_ECN_SEEN 8 -#define TCP_ECN_ECT_PERMANENT 16 enum tcp_tw_status { TCP_TW_SUCCESS = 0, @@ -825,11 +824,6 @@ static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) return max_t(s64, t1 - t0, 0); } -static inline u32 tcp_stamp32_us_delta(u32 t1, u32 t0) -{ - return max_t(s32, t1 - t0, 0); -} - static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) { return tcp_ns_to_ts(skb->skb_mstamp_ns); @@ -905,14 +899,9 @@ struct tcp_skb_cb { /* pkts S/ACKed so far upon tx of skb, incl retrans: */ __u32 delivered; /* start of send pipeline phase */ - u32 first_tx_mstamp; + u64 first_tx_mstamp; /* when we reached the "delivered" count */ - 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 */ + u64 delivered_mstamp; } tx; /* only used for outgoing skbs */ union { struct inet_skb_parm h4; @@ -1038,11 +1027,7 @@ 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 -/* 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) +#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN) union tcp_cc_info; @@ -1062,11 +1047,8 @@ struct ack_sample { */ struct rate_sample { u64 prior_mstamp; /* starting timestamp for interval */ - u32 prior_lost; /* tp->lost at "prior_mstamp" */ u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */ - u32 tx_in_flight; /* packets in flight at starting timestamp */ - s32 lost; /* number of packets lost over interval */ s32 delivered; /* number of packets delivered over interval */ s32 delivered_ce; /* number of packets delivered w/ CE marks*/ long interval_us; /* time for tp->delivered to incr "delivered" */ @@ -1080,7 +1062,6 @@ struct rate_sample { bool is_app_limited; /* is sample from packet with bubble in pipe? */ bool is_retrans; /* is sample from retransmission? */ bool is_ack_delayed; /* is this (likely) a delayed ACK? */ - bool is_ece; /* did this ACK have ECN marked? */ }; struct tcp_congestion_ops { @@ -1104,11 +1085,8 @@ struct tcp_congestion_ops { /* hook for packet ack accounting (optional) */ void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); - /* 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); + /* override sysctl_tcp_min_tso_segs */ + u32 (*min_tso_segs)(struct sock *sk); /* call when packets are delivered to update cwnd and pacing rate, * after all the ca_state processing. (optional) @@ -1171,14 +1149,6 @@ 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); @@ -1198,7 +1168,6 @@ 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); @@ -2191,23 +2160,6 @@ extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, extern void tcp_rack_reo_timeout(struct sock *sk); extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); -/* tcp_plb.c */ - -#define TCP_PLB_SCALE 8 /* scaling factor for fractions in PLB (e.g. ce_ratio) */ - -/* State for PLB (Protective Load Balancing) for a single TCP connection. */ -struct tcp_plb_state { - u8 consec_cong_rounds:5, /* consecutive congested rounds */ - enabled:1, /* Check if PLB is enabled */ - unused:2; - u32 pause_until; /* jiffies32 when PLB can resume repathing */ -}; - -void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb, - const int cong_ratio); -void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb); -void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb); - /* At how many usecs into the future should the RTO fire? */ static inline s64 tcp_rto_delta_us(const struct sock *sk) { diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h index 0e24f11627d51..50655de04c9b6 100644 --- a/include/uapi/linux/inet_diag.h +++ b/include/uapi/linux/inet_diag.h @@ -231,42 +231,9 @@ struct tcp_bbr_info { __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */ }; -/* Phase as reported in netlink/ss stats. */ -enum tcp_bbr2_phase { - BBR2_PHASE_INVALID = 0, - BBR2_PHASE_STARTUP = 1, - BBR2_PHASE_DRAIN = 2, - BBR2_PHASE_PROBE_RTT = 3, - BBR2_PHASE_PROBE_BW_UP = 4, - BBR2_PHASE_PROBE_BW_DOWN = 5, - BBR2_PHASE_PROBE_BW_CRUISE = 6, - BBR2_PHASE_PROBE_BW_REFILL = 7 -}; - -struct tcp_bbr2_info { - /* u64 bw: bandwidth (app throughput) estimate in Byte per sec: */ - __u32 bbr_bw_lsb; /* lower 32 bits of bw */ - __u32 bbr_bw_msb; /* upper 32 bits of bw */ - __u32 bbr_min_rtt; /* min-filtered RTT in uSec */ - __u32 bbr_pacing_gain; /* pacing gain shifted left 8 bits */ - __u32 bbr_cwnd_gain; /* cwnd gain shifted left 8 bits */ - __u32 bbr_bw_hi_lsb; /* lower 32 bits of bw_hi */ - __u32 bbr_bw_hi_msb; /* upper 32 bits of bw_hi */ - __u32 bbr_bw_lo_lsb; /* lower 32 bits of bw_lo */ - __u32 bbr_bw_lo_msb; /* upper 32 bits of bw_lo */ - __u8 bbr_mode; /* current bbr_mode in state machine */ - __u8 bbr_phase; /* current state machine phase */ - __u8 unused1; /* alignment padding; not used yet */ - __u8 bbr_version; /* MUST be at this offset in struct */ - __u32 bbr_inflight_lo; /* lower/short-term data volume bound */ - __u32 bbr_inflight_hi; /* higher/long-term data volume bound */ - __u32 bbr_extra_acked; /* max excess packets ACKed in epoch */ -}; - union tcp_cc_info { struct tcpvegas_info vegas; struct tcp_dctcp_info dctcp; struct tcp_bbr_info bbr; - struct tcp_bbr2_info bbr2; }; #endif /* _UAPI_INET_DIAG_H_ */ diff --git a/include/uapi/linux/snmp.h b/include/uapi/linux/snmp.h index 8ce035f1c8744..4d7470036a8b5 100644 --- a/include/uapi/linux/snmp.h +++ b/include/uapi/linux/snmp.h @@ -292,7 +292,6 @@ enum LINUX_MIB_TCPDSACKIGNOREDDUBIOUS, /* TCPDSACKIgnoredDubious */ LINUX_MIB_TCPMIGRATEREQSUCCESS, /* TCPMigrateReqSuccess */ LINUX_MIB_TCPMIGRATEREQFAILURE, /* TCPMigrateReqFailure */ - LINUX_MIB_TCPECNREHASH, /* TCPECNRehash */ __LINUX_MIB_MAX }; diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index b6bec331a82e4..2dfb12230f089 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -678,24 +678,6 @@ config TCP_CONG_BBR AQM schemes that do not provide a delay signal. It requires the fq ("Fair Queue") pacing packet scheduler. -config TCP_CONG_BBR2 - tristate "BBR2 TCP" - default n - help - - BBR2 TCP congestion control is a model-based congestion control - algorithm that aims to maximize network utilization, keep queues and - retransmit rates low, and to be able to coexist with Reno/CUBIC in - common scenarios. It builds an explicit model of the network path. It - tolerates a targeted degree of random packet loss and delay that are - unrelated to congestion. It can operate over LAN, WAN, cellular, wifi, - or cable modem links, and can use DCTCP-L4S-style ECN signals. It can - coexist with flows that use loss-based congestion control, and can - operate with shallow buffers, deep buffers, bufferbloat, policers, or - AQM schemes that do not provide a delay signal. It requires pacing, - using either TCP internal pacing or the fq ("Fair Queue") pacing packet - scheduler. - choice prompt "Default TCP congestion control" default DEFAULT_CUBIC @@ -733,9 +715,6 @@ choice config DEFAULT_BBR bool "BBR" if TCP_CONG_BBR=y - config DEFAULT_BBR2 - bool "BBR2" if TCP_CONG_BBR2=y - config DEFAULT_RENO bool "Reno" endchoice @@ -760,7 +739,6 @@ config DEFAULT_TCP_CONG default "dctcp" if DEFAULT_DCTCP default "cdg" if DEFAULT_CDG default "bbr" if DEFAULT_BBR - default "bbr2" if DEFAULT_BBR2 default "cubic" config TCP_MD5SIG diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile index e7a86a50838a8..bbdd9c44f14e3 100644 --- a/net/ipv4/Makefile +++ b/net/ipv4/Makefile @@ -10,7 +10,7 @@ obj-y := route.o inetpeer.o protocol.o \ tcp.o tcp_input.o tcp_output.o tcp_timer.o tcp_ipv4.o \ tcp_minisocks.o tcp_cong.o tcp_metrics.o tcp_fastopen.o \ tcp_rate.o tcp_recovery.o tcp_ulp.o \ - tcp_offload.o tcp_plb.o datagram.o raw.o udp.o udplite.o \ + tcp_offload.o datagram.o raw.o udp.o udplite.o \ udp_offload.o arp.o icmp.o devinet.o af_inet.o igmp.o \ fib_frontend.o fib_semantics.o fib_trie.o fib_notifier.o \ inet_fragment.o ping.o ip_tunnel_core.o gre_offload.o \ @@ -46,7 +46,6 @@ obj-$(CONFIG_INET_TCP_DIAG) += tcp_diag.o obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o obj-$(CONFIG_INET_RAW_DIAG) += raw_diag.o obj-$(CONFIG_TCP_CONG_BBR) += tcp_bbr.o -obj-$(CONFIG_TCP_CONG_BBR2) += tcp_bbr2.o obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o obj-$(CONFIG_TCP_CONG_CDG) += tcp_cdg.o obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c index 2c33c19b24230..5386f460bd208 100644 --- a/net/ipv4/proc.c +++ b/net/ipv4/proc.c @@ -297,7 +297,6 @@ static const struct snmp_mib snmp4_net_list[] = { SNMP_MIB_ITEM("TCPDSACKIgnoredDubious", LINUX_MIB_TCPDSACKIGNOREDDUBIOUS), SNMP_MIB_ITEM("TCPMigrateReqSuccess", LINUX_MIB_TCPMIGRATEREQSUCCESS), SNMP_MIB_ITEM("TCPMigrateReqFailure", LINUX_MIB_TCPMIGRATEREQFAILURE), - SNMP_MIB_ITEM("TCPECNRehash", LINUX_MIB_TCPECNREHASH), SNMP_MIB_SENTINEL }; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 4ad677f2b71d8..604ca1ceb1729 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -41,8 +41,6 @@ static int one_day_secs = 24 * 3600; static u32 fib_multipath_hash_fields_all_mask __maybe_unused = FIB_MULTIPATH_HASH_FIELD_ALL_MASK; static unsigned int tcp_child_ehash_entries_max = 16 * 1024 * 1024; -static int tcp_plb_max_rounds = 31; -static int tcp_plb_max_cong_thresh = 256; /* obsolete */ static int sysctl_tcp_low_latency __read_mostly; @@ -1389,47 +1387,6 @@ static struct ctl_table ipv4_net_table[] = { .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_TWO, }, - { - .procname = "tcp_plb_enabled", - .data = &init_net.ipv4.sysctl_tcp_plb_enabled, - .maxlen = sizeof(u8), - .mode = 0644, - .proc_handler = proc_dou8vec_minmax, - .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE, - }, - { - .procname = "tcp_plb_cong_thresh", - .data = &init_net.ipv4.sysctl_tcp_plb_cong_thresh, - .maxlen = sizeof(int), - .mode = 0644, - .proc_handler = proc_dointvec_minmax, - .extra1 = SYSCTL_ZERO, - .extra2 = &tcp_plb_max_cong_thresh, - }, - { - .procname = "tcp_plb_idle_rehash_rounds", - .data = &init_net.ipv4.sysctl_tcp_plb_idle_rehash_rounds, - .maxlen = sizeof(u8), - .mode = 0644, - .proc_handler = proc_dou8vec_minmax, - .extra2 = &tcp_plb_max_rounds, - }, - { - .procname = "tcp_plb_rehash_rounds", - .data = &init_net.ipv4.sysctl_tcp_plb_rehash_rounds, - .maxlen = sizeof(u8), - .mode = 0644, - .proc_handler = proc_dou8vec_minmax, - .extra2 = &tcp_plb_max_rounds, - }, - { - .procname = "tcp_plb_suspend_rto_sec", - .data = &init_net.ipv4.sysctl_tcp_plb_suspend_rto_sec, - .maxlen = sizeof(u8), - .mode = 0644, - .proc_handler = proc_dou8vec_minmax, - }, { .procname = "tcp_collapse_max_bytes", .data = &init_net.ipv4.sysctl_tcp_collapse_max_bytes, diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 3acfcb9a727cb..fab25d4f3a6f1 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -3189,7 +3189,6 @@ int tcp_disconnect(struct sock *sk, int flags) tp->rx_opt.dsack = 0; tp->rx_opt.num_sacks = 0; tp->rcv_ooopack = 0; - tp->fast_ack_mode = 0; /* Clean up fastopen related fields */ diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c index bfbf158c71f4c..54eec33c6e1c6 100644 --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -294,40 +294,26 @@ static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) sk->sk_pacing_rate = rate; } +/* override sysctl_tcp_min_tso_segs */ static u32 bbr_min_tso_segs(struct sock *sk) { return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2; } -/* Return the number of segments BBR would like in a TSO/GSO skb, given - * a particular max gso size as a constraint. - */ -static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now, - u32 gso_max_size) -{ - u32 segs; - u64 bytes; - - /* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */ - bytes = sk->sk_pacing_rate >> sk->sk_pacing_shift; - - bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER); - segs = max_t(u32, div_u64(bytes, mss_now), bbr_min_tso_segs(sk)); - return segs; -} - -/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */ -static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) -{ - return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size); -} - -/* Like bbr_tso_segs(), using mss_cache, ignoring driver's sk_gso_max_size. */ static u32 bbr_tso_segs_goal(struct sock *sk) { struct tcp_sock *tp = tcp_sk(sk); + u32 segs, bytes; + + /* Sort of tcp_tso_autosize() but ignoring + * driver provided sk_gso_max_size. + */ + bytes = min_t(unsigned long, + sk->sk_pacing_rate >> READ_ONCE(sk->sk_pacing_shift), + GSO_LEGACY_MAX_SIZE - 1 - MAX_TCP_HEADER); + segs = max_t(u32, bytes / tp->mss_cache, bbr_min_tso_segs(sk)); - return bbr_tso_segs_generic(sk, tp->mss_cache, GSO_LEGACY_MAX_SIZE); + return min(segs, 0x7FU); } /* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */ @@ -1163,7 +1149,7 @@ static struct tcp_congestion_ops tcp_bbr_cong_ops __read_mostly = { .undo_cwnd = bbr_undo_cwnd, .cwnd_event = bbr_cwnd_event, .ssthresh = bbr_ssthresh, - .tso_segs = bbr_tso_segs, + .min_tso_segs = bbr_min_tso_segs, .get_info = bbr_get_info, .set_state = bbr_set_state, }; diff --git a/net/ipv4/tcp_bbr2.c b/net/ipv4/tcp_bbr2.c deleted file mode 100644 index 2e39f7a353be1..0000000000000 --- a/net/ipv4/tcp_bbr2.c +++ /dev/null @@ -1,2692 +0,0 @@ -/* BBR (Bottleneck Bandwidth and RTT) congestion control, v2 - * - * BBRv2 is a model-based congestion control algorithm that aims for low - * queues, low loss, and (bounded) Reno/CUBIC coexistence. To maintain a model - * of the network path, it uses measurements of bandwidth and RTT, as well as - * (if they occur) packet loss and/or DCTCP/L4S-style ECN signals. Note that - * although it can use ECN or loss signals explicitly, it does not require - * either; it can bound its in-flight data based on its estimate of the BDP. - * - * The model has both higher and lower bounds for the operating range: - * lo: bw_lo, inflight_lo: conservative short-term lower bound - * hi: bw_hi, inflight_hi: robust long-term upper bound - * The bandwidth-probing time scale is (a) extended dynamically based on - * estimated BDP to improve coexistence with Reno/CUBIC; (b) bounded by - * an interactive wall-clock time-scale to be more scalable and responsive - * than Reno and CUBIC. - * - * Here is a state transition diagram for BBR: - * - * | - * V - * +---> STARTUP ----+ - * | | | - * | V | - * | DRAIN ----+ - * | | | - * | V | - * +---> PROBE_BW ----+ - * | ^ | | - * | | | | - * | +----+ | - * | | - * +---- PROBE_RTT <--+ - * - * A BBR flow starts in STARTUP, and ramps up its sending rate quickly. - * When it estimates the pipe is full, it enters DRAIN to drain the queue. - * In steady state a BBR flow only uses PROBE_BW and PROBE_RTT. - * A long-lived BBR flow spends the vast majority of its time remaining - * (repeatedly) in PROBE_BW, fully probing and utilizing the pipe's bandwidth - * in a fair manner, with a small, bounded queue. *If* a flow has been - * continuously sending for the entire min_rtt window, and hasn't seen an RTT - * sample that matches or decreases its min_rtt estimate for 10 seconds, then - * it briefly enters PROBE_RTT to cut inflight to a minimum value to re-probe - * the path's two-way propagation delay (min_rtt). When exiting PROBE_RTT, if - * we estimated that we reached the full bw of the pipe then we enter PROBE_BW; - * otherwise we enter STARTUP to try to fill the pipe. - * - * BBR is described in detail in: - * "BBR: Congestion-Based Congestion Control", - * Neal Cardwell, Yuchung Cheng, C. Stephen Gunn, Soheil Hassas Yeganeh, - * Van Jacobson. ACM Queue, Vol. 14 No. 5, September-October 2016. - * - * There is a public e-mail list for discussing BBR development and testing: - * https://groups.google.com/forum/#!forum/bbr-dev - * - * NOTE: BBR might be used with the fq qdisc ("man tc-fq") with pacing enabled, - * otherwise TCP stack falls back to an internal pacing using one high - * resolution timer per TCP socket and may use more resources. - */ -#include -#include -#include -#include -#include - -#include "tcp_dctcp.h" - -/* Scale factor for rate in pkt/uSec unit to avoid truncation in bandwidth - * estimation. The rate unit ~= (1500 bytes / 1 usec / 2^24) ~= 715 bps. - * This handles bandwidths from 0.06pps (715bps) to 256Mpps (3Tbps) in a u32. - * Since the minimum window is >=4 packets, the lower bound isn't - * an issue. The upper bound isn't an issue with existing technologies. - */ -#define BW_SCALE 24 -#define BW_UNIT (1 << BW_SCALE) - -#define BBR_SCALE 8 /* scaling factor for fractions in BBR (e.g. gains) */ -#define BBR_UNIT (1 << BBR_SCALE) - -#define FLAG_DEBUG_VERBOSE 0x1 /* Verbose debugging messages */ -#define FLAG_DEBUG_LOOPBACK 0x2 /* Do NOT skip loopback addr */ - -#define CYCLE_LEN 8 /* number of phases in a pacing gain cycle */ - -/* BBR has the following modes for deciding how fast to send: */ -enum bbr_mode { - BBR_STARTUP, /* ramp up sending rate rapidly to fill pipe */ - BBR_DRAIN, /* drain any queue created during startup */ - BBR_PROBE_BW, /* discover, share bw: pace around estimated bw */ - BBR_PROBE_RTT, /* cut inflight to min to probe min_rtt */ -}; - -/* How does the incoming ACK stream relate to our bandwidth probing? */ -enum bbr_ack_phase { - BBR_ACKS_INIT, /* not probing; not getting probe feedback */ - BBR_ACKS_REFILLING, /* sending at est. bw to fill pipe */ - BBR_ACKS_PROBE_STARTING, /* inflight rising to probe bw */ - BBR_ACKS_PROBE_FEEDBACK, /* getting feedback from bw probing */ - BBR_ACKS_PROBE_STOPPING, /* stopped probing; still getting feedback */ -}; - -/* BBR congestion control block */ -struct bbr { - u32 min_rtt_us; /* min RTT in min_rtt_win_sec window */ - u32 min_rtt_stamp; /* timestamp of min_rtt_us */ - u32 probe_rtt_done_stamp; /* end time for BBR_PROBE_RTT mode */ - u32 probe_rtt_min_us; /* min RTT in bbr_probe_rtt_win_ms window */ - u32 probe_rtt_min_stamp; /* timestamp of probe_rtt_min_us*/ - u32 next_rtt_delivered; /* scb->tx.delivered at end of round */ - u32 prior_rcv_nxt; /* tp->rcv_nxt when CE state last changed */ - u64 cycle_mstamp; /* time of this cycle phase start */ - u32 mode:3, /* current bbr_mode in state machine */ - prev_ca_state:3, /* CA state on previous ACK */ - packet_conservation:1, /* use packet conservation? */ - round_start:1, /* start of packet-timed tx->ack round? */ - ce_state:1, /* If most recent data has CE bit set */ - bw_probe_up_rounds:5, /* cwnd-limited rounds in PROBE_UP */ - try_fast_path:1, /* can we take fast path? */ - unused2:11, - idle_restart:1, /* restarting after idle? */ - probe_rtt_round_done:1, /* a BBR_PROBE_RTT round at 4 pkts? */ - cycle_idx:3, /* current index in pacing_gain cycle array */ - has_seen_rtt:1; /* have we seen an RTT sample yet? */ - u32 pacing_gain:11, /* current gain for setting pacing rate */ - cwnd_gain:11, /* current gain for setting cwnd */ - full_bw_reached:1, /* reached full bw in Startup? */ - full_bw_cnt:2, /* number of rounds without large bw gains */ - init_cwnd:7; /* initial cwnd */ - u32 prior_cwnd; /* prior cwnd upon entering loss recovery */ - u32 full_bw; /* recent bw, to estimate if pipe is full */ - - /* For tracking ACK aggregation: */ - u64 ack_epoch_mstamp; /* start of ACK sampling epoch */ - u16 extra_acked[2]; /* max excess data ACKed in epoch */ - u32 ack_epoch_acked:20, /* packets (S)ACKed in sampling epoch */ - extra_acked_win_rtts:5, /* age of extra_acked, in round trips */ - extra_acked_win_idx:1, /* current index in extra_acked array */ - /* BBR v2 state: */ - unused1:2, - startup_ecn_rounds:2, /* consecutive hi ECN STARTUP rounds */ - loss_in_cycle:1, /* packet loss in this cycle? */ - ecn_in_cycle:1; /* ECN in this cycle? */ - u32 loss_round_delivered; /* scb->tx.delivered ending loss round */ - u32 undo_bw_lo; /* bw_lo before latest losses */ - u32 undo_inflight_lo; /* inflight_lo before latest losses */ - u32 undo_inflight_hi; /* inflight_hi before latest losses */ - u32 bw_latest; /* max delivered bw in last round trip */ - u32 bw_lo; /* lower bound on sending bandwidth */ - u32 bw_hi[2]; /* upper bound of sending bandwidth range*/ - u32 inflight_latest; /* max delivered data in last round trip */ - u32 inflight_lo; /* lower bound of inflight data range */ - u32 inflight_hi; /* upper bound of inflight data range */ - u32 bw_probe_up_cnt; /* packets delivered per inflight_hi incr */ - u32 bw_probe_up_acks; /* packets (S)ACKed since inflight_hi incr */ - u32 probe_wait_us; /* PROBE_DOWN until next clock-driven probe */ - u32 ecn_eligible:1, /* sender can use ECN (RTT, handshake)? */ - ecn_alpha:9, /* EWMA delivered_ce/delivered; 0..256 */ - bw_probe_samples:1, /* rate samples reflect bw probing? */ - prev_probe_too_high:1, /* did last PROBE_UP go too high? */ - stopped_risky_probe:1, /* last PROBE_UP stopped due to risk? */ - rounds_since_probe:8, /* packet-timed rounds since probed bw */ - loss_round_start:1, /* loss_round_delivered round trip? */ - loss_in_round:1, /* loss marked in this round trip? */ - ecn_in_round:1, /* ECN marked in this round trip? */ - ack_phase:3, /* bbr_ack_phase: meaning of ACKs */ - loss_events_in_round:4,/* losses in STARTUP round */ - initialized:1; /* has bbr_init() been called? */ - u32 alpha_last_delivered; /* tp->delivered at alpha update */ - u32 alpha_last_delivered_ce; /* tp->delivered_ce at alpha update */ - struct tcp_plb_state plb; - - /* Params configurable using setsockopt. Refer to correspoding - * module param for detailed description of params. - */ - struct bbr_params { - u32 high_gain:11, /* max allowed value: 2047 */ - drain_gain:10, /* max allowed value: 1023 */ - cwnd_gain:11; /* max allowed value: 2047 */ - u32 cwnd_min_target:4, /* max allowed value: 15 */ - min_rtt_win_sec:5, /* max allowed value: 31 */ - probe_rtt_mode_ms:9, /* max allowed value: 511 */ - full_bw_cnt:3, /* max allowed value: 7 */ - cwnd_tso_budget:1, /* allowed values: {0, 1} */ - unused3:6, - drain_to_target:1, /* boolean */ - precise_ece_ack:1, /* boolean */ - extra_acked_in_startup:1, /* allowed values: {0, 1} */ - fast_path:1; /* boolean */ - u32 full_bw_thresh:10, /* max allowed value: 1023 */ - startup_cwnd_gain:11, /* max allowed value: 2047 */ - bw_probe_pif_gain:9, /* max allowed value: 511 */ - usage_based_cwnd:1, /* boolean */ - unused2:1; - u16 probe_rtt_win_ms:14, /* max allowed value: 16383 */ - refill_add_inc:2; /* max allowed value: 3 */ - u16 extra_acked_gain:11, /* max allowed value: 2047 */ - extra_acked_win_rtts:5; /* max allowed value: 31*/ - u16 pacing_gain[CYCLE_LEN]; /* max allowed value: 1023 */ - /* Mostly BBR v2 parameters below here: */ - u32 ecn_alpha_gain:8, /* max allowed value: 255 */ - ecn_factor:8, /* max allowed value: 255 */ - ecn_thresh:8, /* max allowed value: 255 */ - beta:8; /* max allowed value: 255 */ - u32 ecn_max_rtt_us:19, /* max allowed value: 524287 */ - bw_probe_reno_gain:9, /* max allowed value: 511 */ - full_loss_cnt:4; /* max allowed value: 15 */ - u32 probe_rtt_cwnd_gain:8, /* max allowed value: 255 */ - inflight_headroom:8, /* max allowed value: 255 */ - loss_thresh:8, /* max allowed value: 255 */ - bw_probe_max_rounds:8; /* max allowed value: 255 */ - u32 bw_probe_rand_rounds:4, /* max allowed value: 15 */ - bw_probe_base_us:26, /* usecs: 0..2^26-1 (67 secs) */ - full_ecn_cnt:2; /* max allowed value: 3 */ - u32 bw_probe_rand_us:26, /* usecs: 0..2^26-1 (67 secs) */ - undo:1, /* boolean */ - tso_rtt_shift:4, /* max allowed value: 15 */ - unused5:1; - u32 ecn_reprobe_gain:9, /* max allowed value: 511 */ - unused1:14, - ecn_alpha_init:9; /* max allowed value: 256 */ - } params; - - struct { - u32 snd_isn; /* Initial sequence number */ - u32 rs_bw; /* last valid rate sample bw */ - u32 target_cwnd; /* target cwnd, based on BDP */ - u8 undo:1, /* Undo even happened but not yet logged */ - unused:7; - char event; /* single-letter event debug codes */ - u16 unused2; - } debug; -}; - -struct bbr_context { - u32 sample_bw; - u32 target_cwnd; - u32 log:1; -}; - -/* Window length of min_rtt filter (in sec). Max allowed value is 31 (0x1F) */ -static u32 bbr_min_rtt_win_sec = 10; -/* Minimum time (in ms) spent at bbr_cwnd_min_target in BBR_PROBE_RTT mode. - * Max allowed value is 511 (0x1FF). - */ -static u32 bbr_probe_rtt_mode_ms = 200; -/* Window length of probe_rtt_min_us filter (in ms), and consequently the - * typical interval between PROBE_RTT mode entries. - * Note that bbr_probe_rtt_win_ms must be <= bbr_min_rtt_win_sec * MSEC_PER_SEC - */ -static u32 bbr_probe_rtt_win_ms = 5000; -/* Skip TSO below the following bandwidth (bits/sec): */ -static int bbr_min_tso_rate = 1200000; - -/* Use min_rtt to help adapt TSO burst size, with smaller min_rtt resulting - * in bigger TSO bursts. By default we cut the RTT-based allowance in half - * for every 2^9 usec (aka 512 us) of RTT, so that the RTT-based allowance - * is below 1500 bytes after 6 * ~500 usec = 3ms. - */ -static u32 bbr_tso_rtt_shift = 9; /* halve allowance per 2^9 usecs, 512us */ - -/* Select cwnd TSO budget approach: - * 0: padding - * 1: flooring - */ -static uint bbr_cwnd_tso_budget = 1; - -/* Pace at ~1% below estimated bw, on average, to reduce queue at bottleneck. - * In order to help drive the network toward lower queues and low latency while - * maintaining high utilization, the average pacing rate aims to be slightly - * lower than the estimated bandwidth. This is an important aspect of the - * design. - */ -static const int bbr_pacing_margin_percent = 1; - -/* We use a high_gain value of 2/ln(2) because it's the smallest pacing gain - * that will allow a smoothly increasing pacing rate that will double each RTT - * and send the same number of packets per RTT that an un-paced, slow-starting - * Reno or CUBIC flow would. Max allowed value is 2047 (0x7FF). - */ -static int bbr_high_gain = BBR_UNIT * 2885 / 1000 + 1; -/* The gain for deriving startup cwnd. Max allowed value is 2047 (0x7FF). */ -static int bbr_startup_cwnd_gain = BBR_UNIT * 2885 / 1000 + 1; -/* The pacing gain of 1/high_gain in BBR_DRAIN is calculated to typically drain - * the queue created in BBR_STARTUP in a single round. Max allowed value - * is 1023 (0x3FF). - */ -static int bbr_drain_gain = BBR_UNIT * 1000 / 2885; -/* The gain for deriving steady-state cwnd tolerates delayed/stretched ACKs. - * Max allowed value is 2047 (0x7FF). - */ -static int bbr_cwnd_gain = BBR_UNIT * 2; -/* The pacing_gain values for the PROBE_BW gain cycle, to discover/share bw. - * Max allowed value for each element is 1023 (0x3FF). - */ -enum bbr_pacing_gain_phase { - BBR_BW_PROBE_UP = 0, /* push up inflight to probe for bw/vol */ - BBR_BW_PROBE_DOWN = 1, /* drain excess inflight from the queue */ - BBR_BW_PROBE_CRUISE = 2, /* use pipe, w/ headroom in queue/pipe */ - BBR_BW_PROBE_REFILL = 3, /* v2: refill the pipe again to 100% */ -}; -static int bbr_pacing_gain[] = { - BBR_UNIT * 5 / 4, /* probe for more available bw */ - BBR_UNIT * 3 / 4, /* drain queue and/or yield bw to other flows */ - BBR_UNIT, BBR_UNIT, BBR_UNIT, /* cruise at 1.0*bw to utilize pipe, */ - BBR_UNIT, BBR_UNIT, BBR_UNIT /* without creating excess queue... */ -}; - -/* Try to keep at least this many packets in flight, if things go smoothly. For - * smooth functioning, a sliding window protocol ACKing every other packet - * needs at least 4 packets in flight. Max allowed value is 15 (0xF). - */ -static u32 bbr_cwnd_min_target = 4; - -/* Cwnd to BDP proportion in PROBE_RTT mode scaled by BBR_UNIT. Default: 50%. - * Use 0 to disable. Max allowed value is 255. - */ -static u32 bbr_probe_rtt_cwnd_gain = BBR_UNIT * 1 / 2; - -/* To estimate if BBR_STARTUP mode (i.e. high_gain) has filled pipe... */ -/* If bw has increased significantly (1.25x), there may be more bw available. - * Max allowed value is 1023 (0x3FF). - */ -static u32 bbr_full_bw_thresh = BBR_UNIT * 5 / 4; -/* But after 3 rounds w/o significant bw growth, estimate pipe is full. - * Max allowed value is 7 (0x7). - */ -static u32 bbr_full_bw_cnt = 3; - -static u32 bbr_flags; /* Debugging related stuff */ - -/* Whether to debug using printk. - */ -static bool bbr_debug_with_printk; - -/* Whether to debug using ftrace event tcp:tcp_bbr_event. - * Ignored when bbr_debug_with_printk is set. - */ -static bool bbr_debug_ftrace; - -/* Experiment: each cycle, try to hold sub-unity gain until inflight <= BDP. */ -static bool bbr_drain_to_target = true; /* default: enabled */ - -/* Experiment: Flags to control BBR with ECN behavior. - */ -static bool bbr_precise_ece_ack = true; /* default: enabled */ - -/* The max rwin scaling shift factor is 14 (RFC 1323), so the max sane rwin is - * (2^(16+14) B)/(1024 B/packet) = 1M packets. - */ -static u32 bbr_cwnd_warn_val = 1U << 20; - -static u16 bbr_debug_port_mask; - -/* BBR module parameters. These are module parameters only in Google prod. - * Upstream these are intentionally not module parameters. - */ -static int bbr_pacing_gain_size = CYCLE_LEN; - -/* Gain factor for adding extra_acked to target cwnd: */ -static int bbr_extra_acked_gain = 256; - -/* Window length of extra_acked window. Max allowed val is 31. */ -static u32 bbr_extra_acked_win_rtts = 5; - -/* Max allowed val for ack_epoch_acked, after which sampling epoch is reset */ -static u32 bbr_ack_epoch_acked_reset_thresh = 1U << 20; - -/* Time period for clamping cwnd increment due to ack aggregation */ -static u32 bbr_extra_acked_max_us = 100 * 1000; - -/* Use extra acked in startup ? - * 0: disabled - * 1: use latest extra_acked value from 1-2 rtt in startup - */ -static int bbr_extra_acked_in_startup = 1; /* default: enabled */ - -/* Experiment: don't grow cwnd beyond twice of what we just probed. */ -static bool bbr_usage_based_cwnd; /* default: disabled */ - -/* For lab testing, researchers can enable BBRv2 ECN support with this flag, - * when they know that any ECN marks that the connections experience will be - * DCTCP/L4S-style ECN marks, rather than RFC3168 ECN marks. - * TODO(ncardwell): Production use of the BBRv2 ECN functionality depends on - * negotiation or configuration that is outside the scope of the BBRv2 - * alpha release. - */ -static bool bbr_ecn_enable = false; - -module_param_named(min_tso_rate, bbr_min_tso_rate, int, 0644); -module_param_named(tso_rtt_shift, bbr_tso_rtt_shift, int, 0644); -module_param_named(high_gain, bbr_high_gain, int, 0644); -module_param_named(drain_gain, bbr_drain_gain, int, 0644); -module_param_named(startup_cwnd_gain, bbr_startup_cwnd_gain, int, 0644); -module_param_named(cwnd_gain, bbr_cwnd_gain, int, 0644); -module_param_array_named(pacing_gain, bbr_pacing_gain, int, - &bbr_pacing_gain_size, 0644); -module_param_named(cwnd_min_target, bbr_cwnd_min_target, uint, 0644); -module_param_named(probe_rtt_cwnd_gain, - bbr_probe_rtt_cwnd_gain, uint, 0664); -module_param_named(cwnd_warn_val, bbr_cwnd_warn_val, uint, 0664); -module_param_named(debug_port_mask, bbr_debug_port_mask, ushort, 0644); -module_param_named(flags, bbr_flags, uint, 0644); -module_param_named(debug_ftrace, bbr_debug_ftrace, bool, 0644); -module_param_named(debug_with_printk, bbr_debug_with_printk, bool, 0644); -module_param_named(min_rtt_win_sec, bbr_min_rtt_win_sec, uint, 0644); -module_param_named(probe_rtt_mode_ms, bbr_probe_rtt_mode_ms, uint, 0644); -module_param_named(probe_rtt_win_ms, bbr_probe_rtt_win_ms, uint, 0644); -module_param_named(full_bw_thresh, bbr_full_bw_thresh, uint, 0644); -module_param_named(full_bw_cnt, bbr_full_bw_cnt, uint, 0644); -module_param_named(cwnd_tso_bduget, bbr_cwnd_tso_budget, uint, 0664); -module_param_named(extra_acked_gain, bbr_extra_acked_gain, int, 0664); -module_param_named(extra_acked_win_rtts, - bbr_extra_acked_win_rtts, uint, 0664); -module_param_named(extra_acked_max_us, - bbr_extra_acked_max_us, uint, 0664); -module_param_named(ack_epoch_acked_reset_thresh, - bbr_ack_epoch_acked_reset_thresh, uint, 0664); -module_param_named(drain_to_target, bbr_drain_to_target, bool, 0664); -module_param_named(precise_ece_ack, bbr_precise_ece_ack, bool, 0664); -module_param_named(extra_acked_in_startup, - bbr_extra_acked_in_startup, int, 0664); -module_param_named(usage_based_cwnd, bbr_usage_based_cwnd, bool, 0664); -module_param_named(ecn_enable, bbr_ecn_enable, bool, 0664); - -static void bbr2_exit_probe_rtt(struct sock *sk); -static void bbr2_reset_congestion_signals(struct sock *sk); - -static void bbr_check_probe_rtt_done(struct sock *sk); - -/* Do we estimate that STARTUP filled the pipe? */ -static bool bbr_full_bw_reached(const struct sock *sk) -{ - const struct bbr *bbr = inet_csk_ca(sk); - - return bbr->full_bw_reached; -} - -/* Return the windowed max recent bandwidth sample, in pkts/uS << BW_SCALE. */ -static u32 bbr_max_bw(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return max(bbr->bw_hi[0], bbr->bw_hi[1]); -} - -/* Return the estimated bandwidth of the path, in pkts/uS << BW_SCALE. */ -static u32 bbr_bw(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return min(bbr_max_bw(sk), bbr->bw_lo); -} - -/* Return maximum extra acked in past k-2k round trips, - * where k = bbr_extra_acked_win_rtts. - */ -static u16 bbr_extra_acked(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return max(bbr->extra_acked[0], bbr->extra_acked[1]); -} - -/* Return rate in bytes per second, optionally with a gain. - * The order here is chosen carefully to avoid overflow of u64. This should - * work for input rates of up to 2.9Tbit/sec and gain of 2.89x. - */ -static u64 bbr_rate_bytes_per_sec(struct sock *sk, u64 rate, int gain, - int margin) -{ - unsigned int mss = tcp_sk(sk)->mss_cache; - - rate *= mss; - rate *= gain; - rate >>= BBR_SCALE; - rate *= USEC_PER_SEC / 100 * (100 - margin); - rate >>= BW_SCALE; - rate = max(rate, 1ULL); - return rate; -} - -static u64 bbr_bw_bytes_per_sec(struct sock *sk, u64 rate) -{ - return bbr_rate_bytes_per_sec(sk, rate, BBR_UNIT, 0); -} - -static u64 bbr_rate_kbps(struct sock *sk, u64 rate) -{ - rate = bbr_bw_bytes_per_sec(sk, rate); - rate *= 8; - do_div(rate, 1000); - return rate; -} - -static u32 bbr_tso_segs_goal(struct sock *sk); -static void bbr_debug(struct sock *sk, u32 acked, - const struct rate_sample *rs, struct bbr_context *ctx) -{ - static const char ca_states[] = { - [TCP_CA_Open] = 'O', - [TCP_CA_Disorder] = 'D', - [TCP_CA_CWR] = 'C', - [TCP_CA_Recovery] = 'R', - [TCP_CA_Loss] = 'L', - }; - static const char mode[] = { - 'G', /* Growing - BBR_STARTUP */ - 'D', /* Drain - BBR_DRAIN */ - 'W', /* Window - BBR_PROBE_BW */ - 'M', /* Min RTT - BBR_PROBE_RTT */ - }; - static const char ack_phase[] = { /* bbr_ack_phase strings */ - 'I', /* BBR_ACKS_INIT - 'Init' */ - 'R', /* BBR_ACKS_REFILLING - 'Refilling' */ - 'B', /* BBR_ACKS_PROBE_STARTING - 'Before' */ - 'F', /* BBR_ACKS_PROBE_FEEDBACK - 'Feedback' */ - 'A', /* BBR_ACKS_PROBE_STOPPING - 'After' */ - }; - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - const u32 una = tp->snd_una - bbr->debug.snd_isn; - const u32 fack = tcp_highest_sack_seq(tp); - const u16 dport = ntohs(inet_sk(sk)->inet_dport); - bool is_port_match = (bbr_debug_port_mask && - ((dport & bbr_debug_port_mask) == 0)); - char debugmsg[320]; - - if (sk->sk_state == TCP_SYN_SENT) - return; /* no bbr_init() yet if SYN retransmit -> CA_Loss */ - - if (!tp->snd_cwnd || tp->snd_cwnd > bbr_cwnd_warn_val) { - char addr[INET6_ADDRSTRLEN + 10] = { 0 }; - - if (sk->sk_family == AF_INET) - snprintf(addr, sizeof(addr), "%pI4:%u", - &inet_sk(sk)->inet_daddr, dport); - else if (sk->sk_family == AF_INET6) - snprintf(addr, sizeof(addr), "%pI6:%u", - &sk->sk_v6_daddr, dport); - - WARN_ONCE(1, - "BBR %s cwnd alert: %u " - "snd_una: %u ca: %d pacing_gain: %u cwnd_gain: %u " - "bw: %u rtt: %u min_rtt: %u " - "acked: %u tso_segs: %u " - "bw: %d %ld %d pif: %u\n", - addr, tp->snd_cwnd, - una, inet_csk(sk)->icsk_ca_state, - bbr->pacing_gain, bbr->cwnd_gain, - bbr_max_bw(sk), (tp->srtt_us >> 3), bbr->min_rtt_us, - acked, bbr_tso_segs_goal(sk), - rs->delivered, rs->interval_us, rs->is_retrans, - tcp_packets_in_flight(tp)); - } - - if (likely(!bbr_debug_with_printk && !bbr_debug_ftrace)) - return; - - if (!sock_flag(sk, SOCK_DBG) && !is_port_match) - return; - - if (!ctx->log && !tp->app_limited && !(bbr_flags & FLAG_DEBUG_VERBOSE)) - return; - - if (ipv4_is_loopback(inet_sk(sk)->inet_daddr) && - !(bbr_flags & FLAG_DEBUG_LOOPBACK)) - return; - - snprintf(debugmsg, sizeof(debugmsg) - 1, - "BBR %pI4:%-5u %5u,%03u:%-7u %c " - "%c %2u br %2u cr %2d rtt %5ld d %2d i %5ld mrtt %d %cbw %llu " - "bw %llu lb %llu ib %llu qb %llu " - "a %u if %2u %c %c dl %u l %u al %u # %u t %u %c %c " - "lr %d er %d ea %d bwl %lld il %d ih %d c %d " - "v %d %c %u %c %s\n", - &inet_sk(sk)->inet_daddr, dport, - una / 1000, una % 1000, fack - tp->snd_una, - ca_states[inet_csk(sk)->icsk_ca_state], - bbr->debug.undo ? '@' : mode[bbr->mode], - tp->snd_cwnd, - bbr_extra_acked(sk), /* br (legacy): extra_acked */ - rs->tx_in_flight, /* cr (legacy): tx_inflight */ - rs->rtt_us, - rs->delivered, - rs->interval_us, - bbr->min_rtt_us, - rs->is_app_limited ? '_' : 'l', - bbr_rate_kbps(sk, ctx->sample_bw), /* lbw: latest sample bw */ - bbr_rate_kbps(sk, bbr_max_bw(sk)), /* bw: max bw */ - 0ULL, /* lb: [obsolete] */ - 0ULL, /* ib: [obsolete] */ - div_u64((u64)sk->sk_pacing_rate * 8, 1000), - acked, - tcp_packets_in_flight(tp), - rs->is_ack_delayed ? 'd' : '.', - bbr->round_start ? '*' : '.', - tp->delivered, tp->lost, - tp->app_limited, - 0, /* #: [obsolete] */ - ctx->target_cwnd, - tp->reord_seen ? 'r' : '.', /* r: reordering seen? */ - ca_states[bbr->prev_ca_state], - (rs->lost + rs->delivered) > 0 ? - (1000 * rs->lost / - (rs->lost + rs->delivered)) : 0, /* lr: loss rate x1000 */ - (rs->delivered) > 0 ? - (1000 * rs->delivered_ce / - (rs->delivered)) : 0, /* er: ECN rate x1000 */ - 1000 * bbr->ecn_alpha >> BBR_SCALE, /* ea: ECN alpha x1000 */ - bbr->bw_lo == ~0U ? - -1 : (s64)bbr_rate_kbps(sk, bbr->bw_lo), /* bwl */ - bbr->inflight_lo, /* il */ - bbr->inflight_hi, /* ih */ - bbr->bw_probe_up_cnt, /* c */ - 2, /* v: version */ - bbr->debug.event, - bbr->cycle_idx, - ack_phase[bbr->ack_phase], - bbr->bw_probe_samples ? "Y" : "N"); - debugmsg[sizeof(debugmsg) - 1] = 0; - - /* printk takes a higher precedence. */ - if (bbr_debug_with_printk) - printk(KERN_DEBUG "%s", debugmsg); - - if (unlikely(bbr->debug.undo)) - bbr->debug.undo = 0; -} - -/* Convert a BBR bw and gain factor to a pacing rate in bytes per second. */ -static unsigned long bbr_bw_to_pacing_rate(struct sock *sk, u32 bw, int gain) -{ - u64 rate = bw; - - rate = bbr_rate_bytes_per_sec(sk, rate, gain, - bbr_pacing_margin_percent); - rate = min_t(u64, rate, sk->sk_max_pacing_rate); - return rate; -} - -/* Initialize pacing rate to: high_gain * init_cwnd / RTT. */ -static void bbr_init_pacing_rate_from_rtt(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u64 bw; - u32 rtt_us; - - if (tp->srtt_us) { /* any RTT sample yet? */ - rtt_us = max(tp->srtt_us >> 3, 1U); - bbr->has_seen_rtt = 1; - } else { /* no RTT sample yet */ - rtt_us = USEC_PER_MSEC; /* use nominal default RTT */ - } - bw = (u64)tp->snd_cwnd * BW_UNIT; - do_div(bw, rtt_us); - sk->sk_pacing_rate = bbr_bw_to_pacing_rate(sk, bw, bbr->params.high_gain); -} - -/* Pace using current bw estimate and a gain factor. */ -static void bbr_set_pacing_rate(struct sock *sk, u32 bw, int gain) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - unsigned long rate = bbr_bw_to_pacing_rate(sk, bw, gain); - - if (unlikely(!bbr->has_seen_rtt && tp->srtt_us)) - bbr_init_pacing_rate_from_rtt(sk); - if (bbr_full_bw_reached(sk) || rate > sk->sk_pacing_rate) - sk->sk_pacing_rate = rate; -} - -static u32 bbr_min_tso_segs(struct sock *sk) -{ - return sk->sk_pacing_rate < (bbr_min_tso_rate >> 3) ? 1 : 2; -} - -/* Return the number of segments BBR would like in a TSO/GSO skb, given - * a particular max gso size as a constraint. - */ -static u32 bbr_tso_segs_generic(struct sock *sk, unsigned int mss_now, - u32 gso_max_size) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 segs, r; - u64 bytes; - - /* Budget a TSO/GSO burst size allowance based on bw (pacing_rate). */ - bytes = sk->sk_pacing_rate >> sk->sk_pacing_shift; - - /* Budget a TSO/GSO burst size allowance based on min_rtt. For every - * K = 2^tso_rtt_shift microseconds of min_rtt, halve the burst. - * The min_rtt-based burst allowance is: 64 KBytes / 2^(min_rtt/K) - */ - if (bbr->params.tso_rtt_shift) { - r = bbr->min_rtt_us >> bbr->params.tso_rtt_shift; - if (r < BITS_PER_TYPE(u32)) /* prevent undefined behavior */ - bytes += GSO_MAX_SIZE >> r; - } - - bytes = min_t(u32, bytes, gso_max_size - 1 - MAX_TCP_HEADER); - segs = max_t(u32, div_u64(bytes, mss_now), bbr_min_tso_segs(sk)); - return segs; -} - -/* Custom tcp_tso_autosize() for BBR, used at transmit time to cap skb size. */ -static u32 bbr_tso_segs(struct sock *sk, unsigned int mss_now) -{ - return bbr_tso_segs_generic(sk, mss_now, sk->sk_gso_max_size); -} - -/* Like bbr_tso_segs(), using mss_cache, ignoring driver's sk_gso_max_size. */ -static u32 bbr_tso_segs_goal(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - - return bbr_tso_segs_generic(sk, tp->mss_cache, GSO_MAX_SIZE); -} - -/* Save "last known good" cwnd so we can restore it after losses or PROBE_RTT */ -static void bbr_save_cwnd(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr->prev_ca_state < TCP_CA_Recovery && bbr->mode != BBR_PROBE_RTT) - bbr->prior_cwnd = tp->snd_cwnd; /* this cwnd is good enough */ - else /* loss recovery or BBR_PROBE_RTT have temporarily cut cwnd */ - bbr->prior_cwnd = max(bbr->prior_cwnd, tp->snd_cwnd); -} - -static void bbr_cwnd_event(struct sock *sk, enum tcp_ca_event event) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - if (event == CA_EVENT_TX_START) { - tcp_plb_check_rehash(sk, &bbr->plb); - - if (!tp->app_limited) - return; - bbr->idle_restart = 1; - bbr->ack_epoch_mstamp = tp->tcp_mstamp; - bbr->ack_epoch_acked = 0; - /* Avoid pointless buffer overflows: pace at est. bw if we don't - * need more speed (we're restarting from idle and app-limited). - */ - if (bbr->mode == BBR_PROBE_BW) - bbr_set_pacing_rate(sk, bbr_bw(sk), BBR_UNIT); - else if (bbr->mode == BBR_PROBE_RTT) - bbr_check_probe_rtt_done(sk); - } else if ((event == CA_EVENT_ECN_IS_CE || - event == CA_EVENT_ECN_NO_CE) && - bbr_ecn_enable && - bbr->params.precise_ece_ack) { - u32 state = bbr->ce_state; - dctcp_ece_ack_update(sk, event, &bbr->prior_rcv_nxt, &state); - bbr->ce_state = state; - if (tp->fast_ack_mode == 2 && event == CA_EVENT_ECN_IS_CE) - tcp_enter_quickack_mode(sk, TCP_MAX_QUICKACKS); - } -} - -/* Calculate bdp based on min RTT and the estimated bottleneck bandwidth: - * - * bdp = ceil(bw * min_rtt * gain) - * - * The key factor, gain, controls the amount of queue. While a small gain - * builds a smaller queue, it becomes more vulnerable to noise in RTT - * measurements (e.g., delayed ACKs or other ACK compression effects). This - * noise may cause BBR to under-estimate the rate. - */ -static u32 bbr_bdp(struct sock *sk, u32 bw, int gain) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 bdp; - u64 w; - - /* If we've never had a valid RTT sample, cap cwnd at the initial - * default. This should only happen when the connection is not using TCP - * timestamps and has retransmitted all of the SYN/SYNACK/data packets - * ACKed so far. In this case, an RTO can cut cwnd to 1, in which - * case we need to slow-start up toward something safe: initial cwnd. - */ - if (unlikely(bbr->min_rtt_us == ~0U)) /* no valid RTT samples yet? */ - return bbr->init_cwnd; /* be safe: cap at initial cwnd */ - - w = (u64)bw * bbr->min_rtt_us; - - /* Apply a gain to the given value, remove the BW_SCALE shift, and - * round the value up to avoid a negative feedback loop. - */ - bdp = (((w * gain) >> BBR_SCALE) + BW_UNIT - 1) / BW_UNIT; - - return bdp; -} - -/* To achieve full performance in high-speed paths, we budget enough cwnd to - * fit full-sized skbs in-flight on both end hosts to fully utilize the path: - * - one skb in sending host Qdisc, - * - one skb in sending host TSO/GSO engine - * - one skb being received by receiver host LRO/GRO/delayed-ACK engine - * Don't worry, at low rates (bbr_min_tso_rate) this won't bloat cwnd because - * in such cases tso_segs_goal is 1. The minimum cwnd is 4 packets, - * which allows 2 outstanding 2-packet sequences, to try to keep pipe - * full even with ACK-every-other-packet delayed ACKs. - */ -static u32 bbr_quantization_budget(struct sock *sk, u32 cwnd) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 tso_segs_goal; - - tso_segs_goal = 3 * bbr_tso_segs_goal(sk); - - /* Allow enough full-sized skbs in flight to utilize end systems. */ - if (bbr->params.cwnd_tso_budget == 1) { - cwnd = max_t(u32, cwnd, tso_segs_goal); - cwnd = max_t(u32, cwnd, bbr->params.cwnd_min_target); - } else { - cwnd += tso_segs_goal; - cwnd = (cwnd + 1) & ~1U; - } - /* Ensure gain cycling gets inflight above BDP even for small BDPs. */ - if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) - cwnd += 2; - - return cwnd; -} - -/* Find inflight based on min RTT and the estimated bottleneck bandwidth. */ -static u32 bbr_inflight(struct sock *sk, u32 bw, int gain) -{ - u32 inflight; - - inflight = bbr_bdp(sk, bw, gain); - inflight = bbr_quantization_budget(sk, inflight); - - return inflight; -} - -/* With pacing at lower layers, there's often less data "in the network" than - * "in flight". With TSQ and departure time pacing at lower layers (e.g. fq), - * we often have several skbs queued in the pacing layer with a pre-scheduled - * earliest departure time (EDT). BBR adapts its pacing rate based on the - * inflight level that it estimates has already been "baked in" by previous - * departure time decisions. We calculate a rough estimate of the number of our - * packets that might be in the network at the earliest departure time for the - * next skb scheduled: - * in_network_at_edt = inflight_at_edt - (EDT - now) * bw - * If we're increasing inflight, then we want to know if the transmit of the - * EDT skb will push inflight above the target, so inflight_at_edt includes - * bbr_tso_segs_goal() from the skb departing at EDT. If decreasing inflight, - * then estimate if inflight will sink too low just before the EDT transmit. - */ -static u32 bbr_packets_in_net_at_edt(struct sock *sk, u32 inflight_now) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u64 now_ns, edt_ns, interval_us; - u32 interval_delivered, inflight_at_edt; - - now_ns = tp->tcp_clock_cache; - edt_ns = max(tp->tcp_wstamp_ns, now_ns); - interval_us = div_u64(edt_ns - now_ns, NSEC_PER_USEC); - interval_delivered = (u64)bbr_bw(sk) * interval_us >> BW_SCALE; - inflight_at_edt = inflight_now; - if (bbr->pacing_gain > BBR_UNIT) /* increasing inflight */ - inflight_at_edt += bbr_tso_segs_goal(sk); /* include EDT skb */ - if (interval_delivered >= inflight_at_edt) - return 0; - return inflight_at_edt - interval_delivered; -} - -/* Find the cwnd increment based on estimate of ack aggregation */ -static u32 bbr_ack_aggregation_cwnd(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 max_aggr_cwnd, aggr_cwnd = 0; - - if (bbr->params.extra_acked_gain && - (bbr_full_bw_reached(sk) || bbr->params.extra_acked_in_startup)) { - max_aggr_cwnd = ((u64)bbr_bw(sk) * bbr_extra_acked_max_us) - / BW_UNIT; - aggr_cwnd = (bbr->params.extra_acked_gain * bbr_extra_acked(sk)) - >> BBR_SCALE; - aggr_cwnd = min(aggr_cwnd, max_aggr_cwnd); - } - - return aggr_cwnd; -} - -/* Returns the cwnd for PROBE_RTT mode. */ -static u32 bbr_probe_rtt_cwnd(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr->params.probe_rtt_cwnd_gain == 0) - return bbr->params.cwnd_min_target; - return max_t(u32, bbr->params.cwnd_min_target, - bbr_bdp(sk, bbr_bw(sk), bbr->params.probe_rtt_cwnd_gain)); -} - -/* Slow-start up toward target cwnd (if bw estimate is growing, or packet loss - * has drawn us down below target), or snap down to target if we're above it. - */ -static void bbr_set_cwnd(struct sock *sk, const struct rate_sample *rs, - u32 acked, u32 bw, int gain, u32 cwnd, - struct bbr_context *ctx) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 target_cwnd = 0, prev_cwnd = tp->snd_cwnd, max_probe; - - if (!acked) - goto done; /* no packet fully ACKed; just apply caps */ - - target_cwnd = bbr_bdp(sk, bw, gain); - - /* Increment the cwnd to account for excess ACKed data that seems - * due to aggregation (of data and/or ACKs) visible in the ACK stream. - */ - target_cwnd += bbr_ack_aggregation_cwnd(sk); - target_cwnd = bbr_quantization_budget(sk, target_cwnd); - - /* If we're below target cwnd, slow start cwnd toward target cwnd. */ - bbr->debug.target_cwnd = target_cwnd; - - /* Update cwnd and enable fast path if cwnd reaches target_cwnd. */ - bbr->try_fast_path = 0; - if (bbr_full_bw_reached(sk)) { /* only cut cwnd if we filled the pipe */ - cwnd += acked; - if (cwnd >= target_cwnd) { - cwnd = target_cwnd; - bbr->try_fast_path = 1; - } - } else if (cwnd < target_cwnd || cwnd < 2 * bbr->init_cwnd) { - cwnd += acked; - } else { - bbr->try_fast_path = 1; - } - - /* When growing cwnd, don't grow beyond twice what we just probed. */ - if (bbr->params.usage_based_cwnd) { - max_probe = max(2 * tp->max_packets_out, tp->snd_cwnd); - cwnd = min(cwnd, max_probe); - } - - cwnd = max_t(u32, cwnd, bbr->params.cwnd_min_target); -done: - tp->snd_cwnd = min(cwnd, tp->snd_cwnd_clamp); /* apply global cap */ - if (bbr->mode == BBR_PROBE_RTT) /* drain queue, refresh min_rtt */ - tp->snd_cwnd = min_t(u32, tp->snd_cwnd, bbr_probe_rtt_cwnd(sk)); - - ctx->target_cwnd = target_cwnd; - ctx->log = (tp->snd_cwnd != prev_cwnd); -} - -/* See if we have reached next round trip */ -static void bbr_update_round_start(struct sock *sk, - const struct rate_sample *rs, struct bbr_context *ctx) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr->round_start = 0; - - /* See if we've reached the next RTT */ - if (rs->interval_us > 0 && - !before(rs->prior_delivered, bbr->next_rtt_delivered)) { - bbr->next_rtt_delivered = tp->delivered; - bbr->round_start = 1; - } -} - -/* Calculate the bandwidth based on how fast packets are delivered */ -static void bbr_calculate_bw_sample(struct sock *sk, - const struct rate_sample *rs, struct bbr_context *ctx) -{ - struct bbr *bbr = inet_csk_ca(sk); - u64 bw = 0; - - /* Divide delivered by the interval to find a (lower bound) bottleneck - * bandwidth sample. Delivered is in packets and interval_us in uS and - * ratio will be <<1 for most connections. So delivered is first scaled. - * Round up to allow growth at low rates, even with integer division. - */ - if (rs->interval_us > 0) { - if (WARN_ONCE(rs->delivered < 0, - "negative delivered: %d interval_us: %ld\n", - rs->delivered, rs->interval_us)) - return; - - bw = DIV_ROUND_UP_ULL((u64)rs->delivered * BW_UNIT, rs->interval_us); - } - - ctx->sample_bw = bw; - bbr->debug.rs_bw = bw; -} - -/* Estimates the windowed max degree of ack aggregation. - * This is used to provision extra in-flight data to keep sending during - * inter-ACK silences. - * - * Degree of ack aggregation is estimated as extra data acked beyond expected. - * - * max_extra_acked = "maximum recent excess data ACKed beyond max_bw * interval" - * cwnd += max_extra_acked - * - * Max extra_acked is clamped by cwnd and bw * bbr_extra_acked_max_us (100 ms). - * Max filter is an approximate sliding window of 5-10 (packet timed) round - * trips for non-startup phase, and 1-2 round trips for startup. - */ -static void bbr_update_ack_aggregation(struct sock *sk, - const struct rate_sample *rs) -{ - u32 epoch_us, expected_acked, extra_acked; - struct bbr *bbr = inet_csk_ca(sk); - struct tcp_sock *tp = tcp_sk(sk); - u32 extra_acked_win_rtts_thresh = bbr->params.extra_acked_win_rtts; - - if (!bbr->params.extra_acked_gain || rs->acked_sacked <= 0 || - rs->delivered < 0 || rs->interval_us <= 0) - return; - - if (bbr->round_start) { - bbr->extra_acked_win_rtts = min(0x1F, - bbr->extra_acked_win_rtts + 1); - if (bbr->params.extra_acked_in_startup && - !bbr_full_bw_reached(sk)) - extra_acked_win_rtts_thresh = 1; - if (bbr->extra_acked_win_rtts >= - extra_acked_win_rtts_thresh) { - bbr->extra_acked_win_rtts = 0; - bbr->extra_acked_win_idx = bbr->extra_acked_win_idx ? - 0 : 1; - bbr->extra_acked[bbr->extra_acked_win_idx] = 0; - } - } - - /* Compute how many packets we expected to be delivered over epoch. */ - epoch_us = tcp_stamp_us_delta(tp->delivered_mstamp, - bbr->ack_epoch_mstamp); - expected_acked = ((u64)bbr_bw(sk) * epoch_us) / BW_UNIT; - - /* Reset the aggregation epoch if ACK rate is below expected rate or - * significantly large no. of ack received since epoch (potentially - * quite old epoch). - */ - if (bbr->ack_epoch_acked <= expected_acked || - (bbr->ack_epoch_acked + rs->acked_sacked >= - bbr_ack_epoch_acked_reset_thresh)) { - bbr->ack_epoch_acked = 0; - bbr->ack_epoch_mstamp = tp->delivered_mstamp; - expected_acked = 0; - } - - /* Compute excess data delivered, beyond what was expected. */ - bbr->ack_epoch_acked = min_t(u32, 0xFFFFF, - bbr->ack_epoch_acked + rs->acked_sacked); - extra_acked = bbr->ack_epoch_acked - expected_acked; - extra_acked = min(extra_acked, tp->snd_cwnd); - if (extra_acked > bbr->extra_acked[bbr->extra_acked_win_idx]) - bbr->extra_acked[bbr->extra_acked_win_idx] = extra_acked; -} - -/* Estimate when the pipe is full, using the change in delivery rate: BBR - * estimates that STARTUP filled the pipe if the estimated bw hasn't changed by - * at least bbr_full_bw_thresh (25%) after bbr_full_bw_cnt (3) non-app-limited - * rounds. Why 3 rounds: 1: rwin autotuning grows the rwin, 2: we fill the - * higher rwin, 3: we get higher delivery rate samples. Or transient - * cross-traffic or radio noise can go away. CUBIC Hystart shares a similar - * design goal, but uses delay and inter-ACK spacing instead of bandwidth. - */ -static void bbr_check_full_bw_reached(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 bw_thresh; - - if (bbr_full_bw_reached(sk) || !bbr->round_start || rs->is_app_limited) - return; - - bw_thresh = (u64)bbr->full_bw * bbr->params.full_bw_thresh >> BBR_SCALE; - if (bbr_max_bw(sk) >= bw_thresh) { - bbr->full_bw = bbr_max_bw(sk); - bbr->full_bw_cnt = 0; - return; - } - ++bbr->full_bw_cnt; - bbr->full_bw_reached = bbr->full_bw_cnt >= bbr->params.full_bw_cnt; -} - -/* If pipe is probably full, drain the queue and then enter steady-state. */ -static bool bbr_check_drain(struct sock *sk, const struct rate_sample *rs, - struct bbr_context *ctx) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr->mode == BBR_STARTUP && bbr_full_bw_reached(sk)) { - bbr->mode = BBR_DRAIN; /* drain queue we created */ - tcp_sk(sk)->snd_ssthresh = - bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); - bbr2_reset_congestion_signals(sk); - } /* fall through to check if in-flight is already small: */ - if (bbr->mode == BBR_DRAIN && - bbr_packets_in_net_at_edt(sk, tcp_packets_in_flight(tcp_sk(sk))) <= - bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT)) - return true; /* exiting DRAIN now */ - return false; -} - -static void bbr_check_probe_rtt_done(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - if (!(bbr->probe_rtt_done_stamp && - after(tcp_jiffies32, bbr->probe_rtt_done_stamp))) - return; - - bbr->probe_rtt_min_stamp = tcp_jiffies32; /* schedule next PROBE_RTT */ - tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd); - bbr2_exit_probe_rtt(sk); -} - -/* The goal of PROBE_RTT mode is to have BBR flows cooperatively and - * periodically drain the bottleneck queue, to converge to measure the true - * min_rtt (unloaded propagation delay). This allows the flows to keep queues - * small (reducing queuing delay and packet loss) and achieve fairness among - * BBR flows. - * - * The min_rtt filter window is 10 seconds. When the min_rtt estimate expires, - * we enter PROBE_RTT mode and cap the cwnd at bbr_cwnd_min_target=4 packets. - * After at least bbr_probe_rtt_mode_ms=200ms and at least one packet-timed - * round trip elapsed with that flight size <= 4, we leave PROBE_RTT mode and - * re-enter the previous mode. BBR uses 200ms to approximately bound the - * performance penalty of PROBE_RTT's cwnd capping to roughly 2% (200ms/10s). - * - * Note that flows need only pay 2% if they are busy sending over the last 10 - * seconds. Interactive applications (e.g., Web, RPCs, video chunks) often have - * natural silences or low-rate periods within 10 seconds where the rate is low - * enough for long enough to drain its queue in the bottleneck. We pick up - * these min RTT measurements opportunistically with our min_rtt filter. :-) - */ -static void bbr_update_min_rtt(struct sock *sk, const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - bool probe_rtt_expired, min_rtt_expired; - u32 expire; - - /* Track min RTT in probe_rtt_win_ms to time next PROBE_RTT state. */ - expire = bbr->probe_rtt_min_stamp + - msecs_to_jiffies(bbr->params.probe_rtt_win_ms); - probe_rtt_expired = after(tcp_jiffies32, expire); - if (rs->rtt_us >= 0 && - (rs->rtt_us <= bbr->probe_rtt_min_us || - (probe_rtt_expired && !rs->is_ack_delayed))) { - bbr->probe_rtt_min_us = rs->rtt_us; - bbr->probe_rtt_min_stamp = tcp_jiffies32; - } - /* Track min RTT seen in the min_rtt_win_sec filter window: */ - expire = bbr->min_rtt_stamp + bbr->params.min_rtt_win_sec * HZ; - min_rtt_expired = after(tcp_jiffies32, expire); - if (bbr->probe_rtt_min_us <= bbr->min_rtt_us || - min_rtt_expired) { - bbr->min_rtt_us = bbr->probe_rtt_min_us; - bbr->min_rtt_stamp = bbr->probe_rtt_min_stamp; - } - - if (bbr->params.probe_rtt_mode_ms > 0 && probe_rtt_expired && - !bbr->idle_restart && bbr->mode != BBR_PROBE_RTT) { - bbr->mode = BBR_PROBE_RTT; /* dip, drain queue */ - bbr_save_cwnd(sk); /* note cwnd so we can restore it */ - bbr->probe_rtt_done_stamp = 0; - bbr->ack_phase = BBR_ACKS_PROBE_STOPPING; - bbr->next_rtt_delivered = tp->delivered; - } - - if (bbr->mode == BBR_PROBE_RTT) { - /* Ignore low rate samples during this mode. */ - tp->app_limited = - (tp->delivered + tcp_packets_in_flight(tp)) ? : 1; - /* Maintain min packets in flight for max(200 ms, 1 round). */ - if (!bbr->probe_rtt_done_stamp && - tcp_packets_in_flight(tp) <= bbr_probe_rtt_cwnd(sk)) { - bbr->probe_rtt_done_stamp = tcp_jiffies32 + - msecs_to_jiffies(bbr->params.probe_rtt_mode_ms); - bbr->probe_rtt_round_done = 0; - bbr->next_rtt_delivered = tp->delivered; - } else if (bbr->probe_rtt_done_stamp) { - if (bbr->round_start) - bbr->probe_rtt_round_done = 1; - if (bbr->probe_rtt_round_done) - bbr_check_probe_rtt_done(sk); - } - } - /* Restart after idle ends only once we process a new S/ACK for data */ - if (rs->delivered > 0) - bbr->idle_restart = 0; -} - -static void bbr_update_gains(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - switch (bbr->mode) { - case BBR_STARTUP: - bbr->pacing_gain = bbr->params.high_gain; - bbr->cwnd_gain = bbr->params.startup_cwnd_gain; - break; - case BBR_DRAIN: - bbr->pacing_gain = bbr->params.drain_gain; /* slow, to drain */ - bbr->cwnd_gain = bbr->params.startup_cwnd_gain; /* keep cwnd */ - break; - case BBR_PROBE_BW: - bbr->pacing_gain = bbr->params.pacing_gain[bbr->cycle_idx]; - bbr->cwnd_gain = bbr->params.cwnd_gain; - break; - case BBR_PROBE_RTT: - bbr->pacing_gain = BBR_UNIT; - bbr->cwnd_gain = BBR_UNIT; - break; - default: - WARN_ONCE(1, "BBR bad mode: %u\n", bbr->mode); - break; - } -} - -static void bbr_init(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - int i; - - WARN_ON_ONCE(tp->snd_cwnd >= bbr_cwnd_warn_val); - - bbr->initialized = 1; - bbr->params.high_gain = min(0x7FF, bbr_high_gain); - bbr->params.drain_gain = min(0x3FF, bbr_drain_gain); - bbr->params.startup_cwnd_gain = min(0x7FF, bbr_startup_cwnd_gain); - bbr->params.cwnd_gain = min(0x7FF, bbr_cwnd_gain); - bbr->params.cwnd_tso_budget = min(0x1U, bbr_cwnd_tso_budget); - bbr->params.cwnd_min_target = min(0xFU, bbr_cwnd_min_target); - bbr->params.min_rtt_win_sec = min(0x1FU, bbr_min_rtt_win_sec); - bbr->params.probe_rtt_mode_ms = min(0x1FFU, bbr_probe_rtt_mode_ms); - bbr->params.full_bw_cnt = min(0x7U, bbr_full_bw_cnt); - bbr->params.full_bw_thresh = min(0x3FFU, bbr_full_bw_thresh); - bbr->params.extra_acked_gain = min(0x7FF, bbr_extra_acked_gain); - bbr->params.extra_acked_win_rtts = min(0x1FU, bbr_extra_acked_win_rtts); - bbr->params.drain_to_target = bbr_drain_to_target ? 1 : 0; - bbr->params.precise_ece_ack = bbr_precise_ece_ack ? 1 : 0; - bbr->params.extra_acked_in_startup = bbr_extra_acked_in_startup ? 1 : 0; - bbr->params.probe_rtt_cwnd_gain = min(0xFFU, bbr_probe_rtt_cwnd_gain); - bbr->params.probe_rtt_win_ms = - min(0x3FFFU, - min_t(u32, bbr_probe_rtt_win_ms, - bbr->params.min_rtt_win_sec * MSEC_PER_SEC)); - for (i = 0; i < CYCLE_LEN; i++) - bbr->params.pacing_gain[i] = min(0x3FF, bbr_pacing_gain[i]); - bbr->params.usage_based_cwnd = bbr_usage_based_cwnd ? 1 : 0; - bbr->params.tso_rtt_shift = min(0xFU, bbr_tso_rtt_shift); - - bbr->debug.snd_isn = tp->snd_una; - bbr->debug.target_cwnd = 0; - bbr->debug.undo = 0; - - bbr->init_cwnd = min(0x7FU, tp->snd_cwnd); - bbr->prior_cwnd = tp->prior_cwnd; - tp->snd_ssthresh = TCP_INFINITE_SSTHRESH; - bbr->next_rtt_delivered = 0; - bbr->prev_ca_state = TCP_CA_Open; - bbr->packet_conservation = 0; - - bbr->probe_rtt_done_stamp = 0; - bbr->probe_rtt_round_done = 0; - bbr->probe_rtt_min_us = tcp_min_rtt(tp); - bbr->probe_rtt_min_stamp = tcp_jiffies32; - bbr->min_rtt_us = tcp_min_rtt(tp); - bbr->min_rtt_stamp = tcp_jiffies32; - - bbr->has_seen_rtt = 0; - bbr_init_pacing_rate_from_rtt(sk); - - bbr->round_start = 0; - bbr->idle_restart = 0; - bbr->full_bw_reached = 0; - bbr->full_bw = 0; - bbr->full_bw_cnt = 0; - bbr->cycle_mstamp = 0; - bbr->cycle_idx = 0; - bbr->mode = BBR_STARTUP; - bbr->debug.rs_bw = 0; - - bbr->ack_epoch_mstamp = tp->tcp_mstamp; - bbr->ack_epoch_acked = 0; - bbr->extra_acked_win_rtts = 0; - bbr->extra_acked_win_idx = 0; - bbr->extra_acked[0] = 0; - bbr->extra_acked[1] = 0; - - bbr->ce_state = 0; - bbr->prior_rcv_nxt = tp->rcv_nxt; - bbr->try_fast_path = 0; - - cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED); -} - -static u32 bbr_sndbuf_expand(struct sock *sk) -{ - /* Provision 3 * cwnd since BBR may slow-start even during recovery. */ - return 3; -} - -/* __________________________________________________________________________ - * - * Functions new to BBR v2 ("bbr") congestion control are below here. - * __________________________________________________________________________ - */ - -/* Incorporate a new bw sample into the current window of our max filter. */ -static void bbr2_take_bw_hi_sample(struct sock *sk, u32 bw) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->bw_hi[1] = max(bw, bbr->bw_hi[1]); -} - -/* Keep max of last 1-2 cycles. Each PROBE_BW cycle, flip filter window. */ -static void bbr2_advance_bw_hi_filter(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (!bbr->bw_hi[1]) - return; /* no samples in this window; remember old window */ - bbr->bw_hi[0] = bbr->bw_hi[1]; - bbr->bw_hi[1] = 0; -} - -/* How much do we want in flight? Our BDP, unless congestion cut cwnd. */ -static u32 bbr2_target_inflight(struct sock *sk) -{ - u32 bdp = bbr_inflight(sk, bbr_bw(sk), BBR_UNIT); - - return min(bdp, tcp_sk(sk)->snd_cwnd); -} - -static bool bbr2_is_probing_bandwidth(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - return (bbr->mode == BBR_STARTUP) || - (bbr->mode == BBR_PROBE_BW && - (bbr->cycle_idx == BBR_BW_PROBE_REFILL || - bbr->cycle_idx == BBR_BW_PROBE_UP)); -} - -/* Has the given amount of time elapsed since we marked the phase start? */ -static bool bbr2_has_elapsed_in_phase(const struct sock *sk, u32 interval_us) -{ - const struct tcp_sock *tp = tcp_sk(sk); - const struct bbr *bbr = inet_csk_ca(sk); - - return tcp_stamp_us_delta(tp->tcp_mstamp, - bbr->cycle_mstamp + interval_us) > 0; -} - -static void bbr2_handle_queue_too_high_in_startup(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->full_bw_reached = 1; - bbr->inflight_hi = bbr_inflight(sk, bbr_max_bw(sk), BBR_UNIT); -} - -/* Exit STARTUP upon N consecutive rounds with ECN mark rate > ecn_thresh. */ -static void bbr2_check_ecn_too_high_in_startup(struct sock *sk, u32 ce_ratio) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr_full_bw_reached(sk) || !bbr->ecn_eligible || - !bbr->params.full_ecn_cnt || !bbr->params.ecn_thresh) - return; - - if (ce_ratio >= bbr->params.ecn_thresh) - bbr->startup_ecn_rounds++; - else - bbr->startup_ecn_rounds = 0; - - if (bbr->startup_ecn_rounds >= bbr->params.full_ecn_cnt) { - bbr->debug.event = 'E'; /* ECN caused STARTUP exit */ - bbr2_handle_queue_too_high_in_startup(sk); - return; - } -} - -static int bbr2_update_ecn_alpha(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - s32 delivered, delivered_ce; - u64 alpha, ce_ratio; - u32 gain; - - if (bbr->params.ecn_factor == 0) - return -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; - - /* See if we should use ECN sender logic for this connection. */ - if (!bbr->ecn_eligible && bbr_ecn_enable && - (bbr->min_rtt_us <= bbr->params.ecn_max_rtt_us || - !bbr->params.ecn_max_rtt_us)) - bbr->ecn_eligible = 1; - - ce_ratio = (u64)delivered_ce << BBR_SCALE; - do_div(ce_ratio, delivered); - gain = bbr->params.ecn_alpha_gain; - alpha = ((BBR_UNIT - gain) * bbr->ecn_alpha) >> BBR_SCALE; - alpha += (gain * ce_ratio) >> BBR_SCALE; - bbr->ecn_alpha = min_t(u32, alpha, BBR_UNIT); - - bbr->alpha_last_delivered = tp->delivered; - bbr->alpha_last_delivered_ce = tp->delivered_ce; - - bbr2_check_ecn_too_high_in_startup(sk, ce_ratio); - return (int)ce_ratio; -} - -/* Each round trip of BBR_BW_PROBE_UP, double volume of probing data. */ -static void bbr2_raise_inflight_hi_slope(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 growth_this_round, cnt; - - /* Calculate "slope": packets S/Acked per inflight_hi increment. */ - growth_this_round = 1 << bbr->bw_probe_up_rounds; - bbr->bw_probe_up_rounds = min(bbr->bw_probe_up_rounds + 1, 30); - cnt = tp->snd_cwnd / growth_this_round; - cnt = max(cnt, 1U); - bbr->bw_probe_up_cnt = cnt; - bbr->debug.event = 'G'; /* Grow inflight_hi slope */ -} - -/* In BBR_BW_PROBE_UP, not seeing high loss/ECN/queue, so raise inflight_hi. */ -static void bbr2_probe_inflight_hi_upward(struct sock *sk, - const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 delta; - - if (!tp->is_cwnd_limited || tp->snd_cwnd < bbr->inflight_hi) { - bbr->bw_probe_up_acks = 0; /* don't accmulate unused credits */ - return; /* not fully using inflight_hi, so don't grow it */ - } - - /* For each bw_probe_up_cnt packets ACKed, increase inflight_hi by 1. */ - bbr->bw_probe_up_acks += rs->acked_sacked; - if (bbr->bw_probe_up_acks >= bbr->bw_probe_up_cnt) { - delta = bbr->bw_probe_up_acks / bbr->bw_probe_up_cnt; - bbr->bw_probe_up_acks -= delta * bbr->bw_probe_up_cnt; - bbr->inflight_hi += delta; - bbr->debug.event = 'I'; /* Increment inflight_hi */ - } - - if (bbr->round_start) - bbr2_raise_inflight_hi_slope(sk); -} - -/* Does loss/ECN rate for this sample say inflight is "too high"? - * This is used by both the bbr_check_loss_too_high_in_startup() function, - * which can be used in either v1 or v2, and the PROBE_UP phase of v2, which - * uses it to notice when loss/ECN rates suggest inflight is too high. - */ -static bool bbr2_is_inflight_too_high(const struct sock *sk, - const struct rate_sample *rs) -{ - const struct bbr *bbr = inet_csk_ca(sk); - u32 loss_thresh, ecn_thresh; - - if (rs->lost > 0 && rs->tx_in_flight) { - loss_thresh = (u64)rs->tx_in_flight * bbr->params.loss_thresh >> - BBR_SCALE; - if (rs->lost > loss_thresh) - return true; - } - - if (rs->delivered_ce > 0 && rs->delivered > 0 && - bbr->ecn_eligible && bbr->params.ecn_thresh) { - ecn_thresh = (u64)rs->delivered * bbr->params.ecn_thresh >> - BBR_SCALE; - if (rs->delivered_ce >= ecn_thresh) - return true; - } - - return false; -} - -/* Calculate the tx_in_flight level that corresponded to excessive loss. - * We find "lost_prefix" segs of the skb where loss rate went too high, - * by solving for "lost_prefix" in the following equation: - * lost / inflight >= loss_thresh - * (lost_prev + lost_prefix) / (inflight_prev + lost_prefix) >= loss_thresh - * Then we take that equation, convert it to fixed point, and - * round up to the nearest packet. - */ -static u32 bbr2_inflight_hi_from_lost_skb(const struct sock *sk, - const struct rate_sample *rs, - const struct sk_buff *skb) -{ - const struct bbr *bbr = inet_csk_ca(sk); - u32 loss_thresh = bbr->params.loss_thresh; - u32 pcount, divisor, inflight_hi; - s32 inflight_prev, lost_prev; - u64 loss_budget, lost_prefix; - - pcount = tcp_skb_pcount(skb); - - /* How much data was in flight before this skb? */ - inflight_prev = rs->tx_in_flight - pcount; - if (WARN_ONCE(inflight_prev < 0, - "tx_in_flight: %u pcount: %u reneg: %u", - rs->tx_in_flight, pcount, tcp_sk(sk)->is_sack_reneg)) - return ~0U; - - /* How much inflight data was marked lost before this skb? */ - lost_prev = rs->lost - pcount; - if (WARN_ON_ONCE(lost_prev < 0)) - return ~0U; - - /* At what prefix of this lost skb did losss rate exceed loss_thresh? */ - loss_budget = (u64)inflight_prev * loss_thresh + BBR_UNIT - 1; - loss_budget >>= BBR_SCALE; - if (lost_prev >= loss_budget) { - lost_prefix = 0; /* previous losses crossed loss_thresh */ - } else { - lost_prefix = loss_budget - lost_prev; - lost_prefix <<= BBR_SCALE; - divisor = BBR_UNIT - loss_thresh; - if (WARN_ON_ONCE(!divisor)) /* loss_thresh is 8 bits */ - return ~0U; - do_div(lost_prefix, divisor); - } - - inflight_hi = inflight_prev + lost_prefix; - return inflight_hi; -} - -/* If loss/ECN rates during probing indicated we may have overfilled a - * buffer, return an operating point that tries to leave unutilized headroom in - * the path for other flows, for fairness convergence and lower RTTs and loss. - */ -static u32 bbr2_inflight_with_headroom(const struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 headroom, headroom_fraction; - - if (bbr->inflight_hi == ~0U) - return ~0U; - - headroom_fraction = bbr->params.inflight_headroom; - headroom = ((u64)bbr->inflight_hi * headroom_fraction) >> BBR_SCALE; - headroom = max(headroom, 1U); - return max_t(s32, bbr->inflight_hi - headroom, - bbr->params.cwnd_min_target); -} - -/* Bound cwnd to a sensible level, based on our current probing state - * machine phase and model of a good inflight level (inflight_lo, inflight_hi). - */ -static void bbr2_bound_cwnd_for_inflight_model(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 cap; - - /* tcp_rcv_synsent_state_process() currently calls tcp_ack() - * and thus cong_control() without first initializing us(!). - */ - if (!bbr->initialized) - return; - - cap = ~0U; - if (bbr->mode == BBR_PROBE_BW && - bbr->cycle_idx != BBR_BW_PROBE_CRUISE) { - /* Probe to see if more packets fit in the path. */ - cap = bbr->inflight_hi; - } else { - if (bbr->mode == BBR_PROBE_RTT || - (bbr->mode == BBR_PROBE_BW && - bbr->cycle_idx == BBR_BW_PROBE_CRUISE)) - cap = bbr2_inflight_with_headroom(sk); - } - /* Adapt to any loss/ECN since our last bw probe. */ - cap = min(cap, bbr->inflight_lo); - - cap = max_t(u32, cap, bbr->params.cwnd_min_target); - tp->snd_cwnd = min(cap, tp->snd_cwnd); -} - -/* Estimate a short-term lower bound on the capacity available now, based - * on measurements of the current delivery process and recent history. When we - * are seeing loss/ECN at times when we are not probing bw, then conservatively - * move toward flow balance by multiplicatively cutting our short-term - * estimated safe rate and volume of data (bw_lo and inflight_lo). We use a - * multiplicative decrease in order to converge to a lower capacity in time - * logarithmic in the magnitude of the decrease. - * - * However, we do not cut our short-term estimates lower than the current rate - * and volume of delivered data from this round trip, since from the current - * delivery process we can estimate the measured capacity available now. - * - * Anything faster than that approach would knowingly risk high loss, which can - * cause low bw for Reno/CUBIC and high loss recovery latency for - * request/response flows using any congestion control. - */ -static void bbr2_adapt_lower_bounds(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u32 ecn_cut, ecn_inflight_lo, beta; - - /* We only use lower-bound estimates when not probing bw. - * When probing we need to push inflight higher to probe bw. - */ - if (bbr2_is_probing_bandwidth(sk)) - return; - - /* ECN response. */ - if (bbr->ecn_in_round && bbr->ecn_eligible && bbr->params.ecn_factor) { - /* Reduce inflight to (1 - alpha*ecn_factor). */ - ecn_cut = (BBR_UNIT - - ((bbr->ecn_alpha * bbr->params.ecn_factor) >> - BBR_SCALE)); - if (bbr->inflight_lo == ~0U) - bbr->inflight_lo = tp->snd_cwnd; - ecn_inflight_lo = (u64)bbr->inflight_lo * ecn_cut >> BBR_SCALE; - } else { - ecn_inflight_lo = ~0U; - } - - /* Loss response. */ - if (bbr->loss_in_round) { - /* Reduce bw and inflight to (1 - beta). */ - if (bbr->bw_lo == ~0U) - bbr->bw_lo = bbr_max_bw(sk); - if (bbr->inflight_lo == ~0U) - bbr->inflight_lo = tp->snd_cwnd; - beta = bbr->params.beta; - bbr->bw_lo = - max_t(u32, bbr->bw_latest, - (u64)bbr->bw_lo * - (BBR_UNIT - beta) >> BBR_SCALE); - bbr->inflight_lo = - max_t(u32, bbr->inflight_latest, - (u64)bbr->inflight_lo * - (BBR_UNIT - beta) >> BBR_SCALE); - } - - /* Adjust to the lower of the levels implied by loss or ECN. */ - bbr->inflight_lo = min(bbr->inflight_lo, ecn_inflight_lo); -} - -/* Reset any short-term lower-bound adaptation to congestion, so that we can - * push our inflight up. - */ -static void bbr2_reset_lower_bounds(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->bw_lo = ~0U; - bbr->inflight_lo = ~0U; -} - -/* After bw probing (STARTUP/PROBE_UP), reset signals before entering a state - * machine phase where we adapt our lower bound based on congestion signals. - */ -static void bbr2_reset_congestion_signals(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->loss_in_round = 0; - bbr->ecn_in_round = 0; - bbr->loss_in_cycle = 0; - bbr->ecn_in_cycle = 0; - bbr->bw_latest = 0; - bbr->inflight_latest = 0; -} - -/* Update (most of) our congestion signals: track the recent rate and volume of - * delivered data, presence of loss, and EWMA degree of ECN marking. - */ -static void bbr2_update_congestion_signals( - struct sock *sk, const struct rate_sample *rs, struct bbr_context *ctx) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - u64 bw; - - bbr->loss_round_start = 0; - if (rs->interval_us <= 0 || !rs->acked_sacked) - return; /* Not a valid observation */ - bw = ctx->sample_bw; - - if (!rs->is_app_limited || bw >= bbr_max_bw(sk)) - bbr2_take_bw_hi_sample(sk, bw); - - bbr->loss_in_round |= (rs->losses > 0); - - /* Update rate and volume of delivered data from latest round trip: */ - bbr->bw_latest = max_t(u32, bbr->bw_latest, ctx->sample_bw); - bbr->inflight_latest = max_t(u32, bbr->inflight_latest, rs->delivered); - - if (before(rs->prior_delivered, bbr->loss_round_delivered)) - return; /* skip the per-round-trip updates */ - /* Now do per-round-trip updates. */ - bbr->loss_round_delivered = tp->delivered; /* mark round trip */ - bbr->loss_round_start = 1; - bbr2_adapt_lower_bounds(sk); - - /* Update windowed "latest" (single-round-trip) filters. */ - bbr->loss_in_round = 0; - bbr->ecn_in_round = 0; - bbr->bw_latest = ctx->sample_bw; - bbr->inflight_latest = rs->delivered; -} - -/* Bandwidth probing can cause loss. To help coexistence with loss-based - * congestion control we spread out our probing in a Reno-conscious way. Due to - * the shape of the Reno sawtooth, the time required between loss epochs for an - * idealized Reno flow is a number of round trips that is the BDP of that - * flow. We count packet-timed round trips directly, since measured RTT can - * vary widely, and Reno is driven by packet-timed round trips. - */ -static bool bbr2_is_reno_coexistence_probe_time(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 inflight, rounds, reno_gain, reno_rounds; - - /* Random loss can shave some small percentage off of our inflight - * in each round. To survive this, flows need robust periodic probes. - */ - rounds = bbr->params.bw_probe_max_rounds; - - reno_gain = bbr->params.bw_probe_reno_gain; - if (reno_gain) { - inflight = bbr2_target_inflight(sk); - reno_rounds = ((u64)inflight * reno_gain) >> BBR_SCALE; - rounds = min(rounds, reno_rounds); - } - return bbr->rounds_since_probe >= rounds; -} - -/* How long do we want to wait before probing for bandwidth (and risking - * loss)? We randomize the wait, for better mixing and fairness convergence. - * - * We bound the Reno-coexistence inter-bw-probe time to be 62-63 round trips. - * This is calculated to allow fairness with a 25Mbps, 30ms Reno flow, - * (eg 4K video to a broadband user): - * BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets - * - * We bound the BBR-native inter-bw-probe wall clock time to be: - * (a) higher than 2 sec: to try to avoid causing loss for a long enough time - * to allow Reno at 30ms to get 4K video bw, the inter-bw-probe time must - * be at least: 25Mbps * .030sec / (1514bytes) * 0.030sec = 1.9secs - * (b) lower than 3 sec: to ensure flows can start probing in a reasonable - * amount of time to discover unutilized bw on human-scale interactive - * time-scales (e.g. perhaps traffic from a web page download that we - * were competing with is now complete). - */ -static void bbr2_pick_probe_wait(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - /* Decide the random round-trip bound for wait until probe: */ - bbr->rounds_since_probe = - prandom_u32_max(bbr->params.bw_probe_rand_rounds); - /* Decide the random wall clock bound for wait until probe: */ - bbr->probe_wait_us = bbr->params.bw_probe_base_us + - prandom_u32_max(bbr->params.bw_probe_rand_us); -} - -static void bbr2_set_cycle_idx(struct sock *sk, int cycle_idx) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr->cycle_idx = cycle_idx; - /* New phase, so need to update cwnd and pacing rate. */ - bbr->try_fast_path = 0; -} - -/* Send at estimated bw to fill the pipe, but not queue. We need this phase - * before PROBE_UP, because as soon as we send faster than the available bw - * we will start building a queue, and if the buffer is shallow we can cause - * loss. If we do not fill the pipe before we cause this loss, our bw_hi and - * inflight_hi estimates will underestimate. - */ -static void bbr2_start_bw_probe_refill(struct sock *sk, u32 bw_probe_up_rounds) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr2_reset_lower_bounds(sk); - if (bbr->inflight_hi != ~0U) - bbr->inflight_hi += bbr->params.refill_add_inc; - bbr->bw_probe_up_rounds = bw_probe_up_rounds; - bbr->bw_probe_up_acks = 0; - bbr->stopped_risky_probe = 0; - bbr->ack_phase = BBR_ACKS_REFILLING; - bbr->next_rtt_delivered = tp->delivered; - bbr2_set_cycle_idx(sk, BBR_BW_PROBE_REFILL); -} - -/* Now probe max deliverable data rate and volume. */ -static void bbr2_start_bw_probe_up(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr->ack_phase = BBR_ACKS_PROBE_STARTING; - bbr->next_rtt_delivered = tp->delivered; - bbr->cycle_mstamp = tp->tcp_mstamp; - bbr2_set_cycle_idx(sk, BBR_BW_PROBE_UP); - bbr2_raise_inflight_hi_slope(sk); -} - -/* Start a new PROBE_BW probing cycle of some wall clock length. Pick a wall - * clock time at which to probe beyond an inflight that we think to be - * safe. This will knowingly risk packet loss, so we want to do this rarely, to - * keep packet loss rates low. Also start a round-trip counter, to probe faster - * if we estimate a Reno flow at our BDP would probe faster. - */ -static void bbr2_start_bw_probe_down(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr2_reset_congestion_signals(sk); - bbr->bw_probe_up_cnt = ~0U; /* not growing inflight_hi any more */ - bbr2_pick_probe_wait(sk); - bbr->cycle_mstamp = tp->tcp_mstamp; /* start wall clock */ - bbr->ack_phase = BBR_ACKS_PROBE_STOPPING; - bbr->next_rtt_delivered = tp->delivered; - bbr2_set_cycle_idx(sk, BBR_BW_PROBE_DOWN); -} - -/* Cruise: maintain what we estimate to be a neutral, conservative - * operating point, without attempting to probe up for bandwidth or down for - * RTT, and only reducing inflight in response to loss/ECN signals. - */ -static void bbr2_start_bw_probe_cruise(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr->inflight_lo != ~0U) - bbr->inflight_lo = min(bbr->inflight_lo, bbr->inflight_hi); - - bbr2_set_cycle_idx(sk, BBR_BW_PROBE_CRUISE); -} - -/* Loss and/or ECN rate is too high while probing. - * Adapt (once per bw probe) by cutting inflight_hi and then restarting cycle. - */ -static void bbr2_handle_inflight_too_high(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - const u32 beta = bbr->params.beta; - - bbr->prev_probe_too_high = 1; - bbr->bw_probe_samples = 0; /* only react once per probe */ - bbr->debug.event = 'L'; /* Loss/ECN too high */ - /* If we are app-limited then we are not robustly - * probing the max volume of inflight data we think - * might be safe (analogous to how app-limited bw - * samples are not known to be robustly probing bw). - */ - if (!rs->is_app_limited) - bbr->inflight_hi = max_t(u32, rs->tx_in_flight, - (u64)bbr2_target_inflight(sk) * - (BBR_UNIT - beta) >> BBR_SCALE); - if (bbr->mode == BBR_PROBE_BW && bbr->cycle_idx == BBR_BW_PROBE_UP) - bbr2_start_bw_probe_down(sk); -} - -/* If we're seeing bw and loss samples reflecting our bw probing, adapt - * using the signals we see. If loss or ECN mark rate gets too high, then adapt - * inflight_hi downward. If we're able to push inflight higher without such - * signals, push higher: adapt inflight_hi upward. - */ -static bool bbr2_adapt_upper_bounds(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - - /* Track when we'll see bw/loss samples resulting from our bw probes. */ - if (bbr->ack_phase == BBR_ACKS_PROBE_STARTING && bbr->round_start) - bbr->ack_phase = BBR_ACKS_PROBE_FEEDBACK; - if (bbr->ack_phase == BBR_ACKS_PROBE_STOPPING && bbr->round_start) { - /* End of samples from bw probing phase. */ - bbr->bw_probe_samples = 0; - bbr->ack_phase = BBR_ACKS_INIT; - /* At this point in the cycle, our current bw sample is also - * our best recent chance at finding the highest available bw - * for this flow. So now is the best time to forget the bw - * samples from the previous cycle, by advancing the window. - */ - if (bbr->mode == BBR_PROBE_BW && !rs->is_app_limited) - bbr2_advance_bw_hi_filter(sk); - /* If we had an inflight_hi, then probed and pushed inflight all - * the way up to hit that inflight_hi without seeing any - * high loss/ECN in all the resulting ACKs from that probing, - * then probe up again, this time letting inflight persist at - * inflight_hi for a round trip, then accelerating beyond. - */ - if (bbr->mode == BBR_PROBE_BW && - bbr->stopped_risky_probe && !bbr->prev_probe_too_high) { - bbr->debug.event = 'R'; /* reprobe */ - bbr2_start_bw_probe_refill(sk, 0); - return true; /* yes, decided state transition */ - } - } - - if (bbr2_is_inflight_too_high(sk, rs)) { - if (bbr->bw_probe_samples) /* sample is from bw probing? */ - bbr2_handle_inflight_too_high(sk, rs); - } else { - /* Loss/ECN rate is declared safe. Adjust upper bound upward. */ - if (bbr->inflight_hi == ~0U) /* no excess queue signals yet? */ - return false; - - /* To be resilient to random loss, we must raise inflight_hi - * if we observe in any phase that a higher level is safe. - */ - if (rs->tx_in_flight > bbr->inflight_hi) { - bbr->inflight_hi = rs->tx_in_flight; - bbr->debug.event = 'U'; /* raise up inflight_hi */ - } - - if (bbr->mode == BBR_PROBE_BW && - bbr->cycle_idx == BBR_BW_PROBE_UP) - bbr2_probe_inflight_hi_upward(sk, rs); - } - - return false; -} - -/* Check if it's time to probe for bandwidth now, and if so, kick it off. */ -static bool bbr2_check_time_to_probe_bw(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 n; - - /* If we seem to be at an operating point where we are not seeing loss - * but we are seeing ECN marks, then when the ECN marks cease we reprobe - * quickly (in case a burst of cross-traffic has ceased and freed up bw, - * or in case we are sharing with multiplicatively probing traffic). - */ - if (bbr->params.ecn_reprobe_gain && bbr->ecn_eligible && - bbr->ecn_in_cycle && !bbr->loss_in_cycle && - inet_csk(sk)->icsk_ca_state == TCP_CA_Open) { - bbr->debug.event = 'A'; /* *A*ll clear to probe *A*gain */ - /* Calculate n so that when bbr2_raise_inflight_hi_slope() - * computes growth_this_round as 2^n it will be roughly the - * desired volume of data (inflight_hi*ecn_reprobe_gain). - */ - n = ilog2((((u64)bbr->inflight_hi * - bbr->params.ecn_reprobe_gain) >> BBR_SCALE)); - bbr2_start_bw_probe_refill(sk, n); - return true; - } - - if (bbr2_has_elapsed_in_phase(sk, bbr->probe_wait_us) || - bbr2_is_reno_coexistence_probe_time(sk)) { - bbr2_start_bw_probe_refill(sk, 0); - return true; - } - return false; -} - -/* Is it time to transition from PROBE_DOWN to PROBE_CRUISE? */ -static bool bbr2_check_time_to_cruise(struct sock *sk, u32 inflight, u32 bw) -{ - struct bbr *bbr = inet_csk_ca(sk); - bool is_under_bdp, is_long_enough; - - /* Always need to pull inflight down to leave headroom in queue. */ - if (inflight > bbr2_inflight_with_headroom(sk)) - return false; - - is_under_bdp = inflight <= bbr_inflight(sk, bw, BBR_UNIT); - if (bbr->params.drain_to_target) - return is_under_bdp; - - is_long_enough = bbr2_has_elapsed_in_phase(sk, bbr->min_rtt_us); - return is_under_bdp || is_long_enough; -} - -/* PROBE_BW state machine: cruise, refill, probe for bw, or drain? */ -static void bbr2_update_cycle_phase(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - bool is_risky = false, is_queuing = false; - u32 inflight, bw; - - if (!bbr_full_bw_reached(sk)) - return; - - /* In DRAIN, PROBE_BW, or PROBE_RTT, adjust upper bounds. */ - if (bbr2_adapt_upper_bounds(sk, rs)) - return; /* already decided state transition */ - - if (bbr->mode != BBR_PROBE_BW) - return; - - inflight = bbr_packets_in_net_at_edt(sk, rs->prior_in_flight); - bw = bbr_max_bw(sk); - - switch (bbr->cycle_idx) { - /* First we spend most of our time cruising with a pacing_gain of 1.0, - * which paces at the estimated bw, to try to fully use the pipe - * without building queue. If we encounter loss/ECN marks, we adapt - * by slowing down. - */ - case BBR_BW_PROBE_CRUISE: - if (bbr2_check_time_to_probe_bw(sk)) - return; /* already decided state transition */ - break; - - /* After cruising, when it's time to probe, we first "refill": we send - * at the estimated bw to fill the pipe, before probing higher and - * knowingly risking overflowing the bottleneck buffer (causing loss). - */ - case BBR_BW_PROBE_REFILL: - if (bbr->round_start) { - /* After one full round trip of sending in REFILL, we - * start to see bw samples reflecting our REFILL, which - * may be putting too much data in flight. - */ - bbr->bw_probe_samples = 1; - bbr2_start_bw_probe_up(sk); - } - break; - - /* After we refill the pipe, we probe by using a pacing_gain > 1.0, to - * probe for bw. If we have not seen loss/ECN, we try to raise inflight - * to at least pacing_gain*BDP; note that this may take more than - * min_rtt if min_rtt is small (e.g. on a LAN). - * - * We terminate PROBE_UP bandwidth probing upon any of the following: - * - * (1) We've pushed inflight up to hit the inflight_hi target set in the - * most recent previous bw probe phase. Thus we want to start - * draining the queue immediately because it's very likely the most - * recently sent packets will fill the queue and cause drops. - * (checked here) - * (2) We have probed for at least 1*min_rtt_us, and the - * estimated queue is high enough (inflight > 1.25 * estimated_bdp). - * (checked here) - * (3) Loss filter says loss rate is "too high". - * (checked in bbr_is_inflight_too_high()) - * (4) ECN filter says ECN mark rate is "too high". - * (checked in bbr_is_inflight_too_high()) - */ - case BBR_BW_PROBE_UP: - if (bbr->prev_probe_too_high && - inflight >= bbr->inflight_hi) { - bbr->stopped_risky_probe = 1; - is_risky = true; - bbr->debug.event = 'D'; /* D for danger */ - } else if (bbr2_has_elapsed_in_phase(sk, bbr->min_rtt_us) && - inflight >= - bbr_inflight(sk, bw, - bbr->params.bw_probe_pif_gain)) { - is_queuing = true; - bbr->debug.event = 'Q'; /* building Queue */ - } - if (is_risky || is_queuing) { - bbr->prev_probe_too_high = 0; /* no loss/ECN (yet) */ - bbr2_start_bw_probe_down(sk); /* restart w/ down */ - } - break; - - /* After probing in PROBE_UP, we have usually accumulated some data in - * the bottleneck buffer (if bw probing didn't find more bw). We next - * enter PROBE_DOWN to try to drain any excess data from the queue. To - * do this, we use a pacing_gain < 1.0. We hold this pacing gain until - * our inflight is less then that target cruising point, which is the - * minimum of (a) the amount needed to leave headroom, and (b) the - * estimated BDP. Once inflight falls to match the target, we estimate - * the queue is drained; persisting would underutilize the pipe. - */ - case BBR_BW_PROBE_DOWN: - if (bbr2_check_time_to_probe_bw(sk)) - return; /* already decided state transition */ - if (bbr2_check_time_to_cruise(sk, inflight, bw)) - bbr2_start_bw_probe_cruise(sk); - break; - - default: - WARN_ONCE(1, "BBR invalid cycle index %u\n", bbr->cycle_idx); - } -} - -/* Exiting PROBE_RTT, so return to bandwidth probing in STARTUP or PROBE_BW. */ -static void bbr2_exit_probe_rtt(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr2_reset_lower_bounds(sk); - if (bbr_full_bw_reached(sk)) { - bbr->mode = BBR_PROBE_BW; - /* Raising inflight after PROBE_RTT may cause loss, so reset - * the PROBE_BW clock and schedule the next bandwidth probe for - * a friendly and randomized future point in time. - */ - bbr2_start_bw_probe_down(sk); - /* Since we are exiting PROBE_RTT, we know inflight is - * below our estimated BDP, so it is reasonable to cruise. - */ - bbr2_start_bw_probe_cruise(sk); - } else { - bbr->mode = BBR_STARTUP; - } -} - -/* Exit STARTUP based on loss rate > 1% and loss gaps in round >= N. Wait until - * the end of the round in recovery to get a good estimate of how many packets - * have been lost, and how many we need to drain with a low pacing rate. - */ -static void bbr2_check_loss_too_high_in_startup(struct sock *sk, - const struct rate_sample *rs) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr_full_bw_reached(sk)) - return; - - /* For STARTUP exit, check the loss rate at the end of each round trip - * of Recovery episodes in STARTUP. We check the loss rate at the end - * of the round trip to filter out noisy/low loss and have a better - * sense of inflight (extent of loss), so we can drain more accurately. - */ - if (rs->losses && bbr->loss_events_in_round < 0xf) - bbr->loss_events_in_round++; /* update saturating counter */ - if (bbr->params.full_loss_cnt && bbr->loss_round_start && - inet_csk(sk)->icsk_ca_state == TCP_CA_Recovery && - bbr->loss_events_in_round >= bbr->params.full_loss_cnt && - bbr2_is_inflight_too_high(sk, rs)) { - bbr->debug.event = 'P'; /* Packet loss caused STARTUP exit */ - bbr2_handle_queue_too_high_in_startup(sk); - return; - } - if (bbr->loss_round_start) - bbr->loss_events_in_round = 0; -} - -/* If we are done draining, advance into steady state operation in PROBE_BW. */ -static void bbr2_check_drain(struct sock *sk, const struct rate_sample *rs, - struct bbr_context *ctx) -{ - struct bbr *bbr = inet_csk_ca(sk); - - if (bbr_check_drain(sk, rs, ctx)) { - bbr->mode = BBR_PROBE_BW; - bbr2_start_bw_probe_down(sk); - } -} - -static void bbr2_update_model(struct sock *sk, const struct rate_sample *rs, - struct bbr_context *ctx) -{ - bbr2_update_congestion_signals(sk, rs, ctx); - bbr_update_ack_aggregation(sk, rs); - bbr2_check_loss_too_high_in_startup(sk, rs); - bbr_check_full_bw_reached(sk, rs); - bbr2_check_drain(sk, rs, ctx); - bbr2_update_cycle_phase(sk, rs); - bbr_update_min_rtt(sk, rs); -} - -/* Fast path for app-limited case. - * - * On each ack, we execute bbr state machine, which primarily consists of: - * 1) update model based on new rate sample, and - * 2) update control based on updated model or state change. - * - * There are certain workload/scenarios, e.g. app-limited case, where - * either we can skip updating model or we can skip update of both model - * as well as control. This provides signifcant softirq cpu savings for - * processing incoming acks. - * - * In case of app-limited, if there is no congestion (loss/ecn) and - * if observed bw sample is less than current estimated bw, then we can - * skip some of the computation in bbr state processing: - * - * - if there is no rtt/mode/phase change: In this case, since all the - * parameters of the network model are constant, we can skip model - * as well control update. - * - * - else we can skip rest of the model update. But we still need to - * update the control to account for the new rtt/mode/phase. - * - * Returns whether we can take fast path or not. - */ -static bool bbr2_fast_path(struct sock *sk, bool *update_model, - const struct rate_sample *rs, struct bbr_context *ctx) -{ - struct bbr *bbr = inet_csk_ca(sk); - u32 prev_min_rtt_us, prev_mode; - - if (bbr->params.fast_path && bbr->try_fast_path && - rs->is_app_limited && ctx->sample_bw < bbr_max_bw(sk) && - !bbr->loss_in_round && !bbr->ecn_in_round) { - prev_mode = bbr->mode; - prev_min_rtt_us = bbr->min_rtt_us; - bbr2_check_drain(sk, rs, ctx); - bbr2_update_cycle_phase(sk, rs); - bbr_update_min_rtt(sk, rs); - - if (bbr->mode == prev_mode && - bbr->min_rtt_us == prev_min_rtt_us && - bbr->try_fast_path) - return true; - - /* Skip model update, but control still needs to be updated */ - *update_model = false; - } - return false; -} - -static void bbr2_main(struct sock *sk, const struct rate_sample *rs) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - struct bbr_context ctx = { 0 }; - bool update_model = true; - u32 bw; - int ce_ratio = -1; - - bbr->debug.event = '.'; /* init to default NOP (no event yet) */ - - bbr_update_round_start(sk, rs, &ctx); - if (bbr->round_start) { - bbr->rounds_since_probe = - min_t(s32, bbr->rounds_since_probe + 1, 0xFF); - ce_ratio = bbr2_update_ecn_alpha(sk); - tcp_plb_update_state(sk, &bbr->plb, ce_ratio); - tcp_plb_check_rehash(sk, &bbr->plb); - } - - bbr->ecn_in_round |= rs->is_ece; - bbr_calculate_bw_sample(sk, rs, &ctx); - - if (bbr2_fast_path(sk, &update_model, rs, &ctx)) - goto out; - - if (update_model) - bbr2_update_model(sk, rs, &ctx); - - bbr_update_gains(sk); - bw = bbr_bw(sk); - bbr_set_pacing_rate(sk, bw, bbr->pacing_gain); - bbr_set_cwnd(sk, rs, rs->acked_sacked, bw, bbr->cwnd_gain, - tp->snd_cwnd, &ctx); - bbr2_bound_cwnd_for_inflight_model(sk); - -out: - bbr->prev_ca_state = inet_csk(sk)->icsk_ca_state; - bbr->loss_in_cycle |= rs->lost > 0; - bbr->ecn_in_cycle |= rs->delivered_ce > 0; - - bbr_debug(sk, rs->acked_sacked, rs, &ctx); -} - -/* Module parameters that are settable by TCP_CONGESTION_PARAMS are declared - * down here, so that the algorithm functions that use the parameters must use - * the per-socket parameters; if they accidentally use the global version - * then there will be a compile error. - * TODO(ncardwell): move all per-socket parameters down to this section. - */ - -/* On losses, scale down inflight and pacing rate by beta scaled by BBR_SCALE. - * No loss response when 0. Max allwed value is 255. - */ -static u32 bbr_beta = BBR_UNIT * 30 / 100; - -/* Gain factor for ECN mark ratio samples, scaled by BBR_SCALE. - * Max allowed value is 255. - */ -static u32 bbr_ecn_alpha_gain = BBR_UNIT * 1 / 16; /* 1/16 = 6.25% */ - -/* The initial value for the ecn_alpha state variable. Default and max - * BBR_UNIT (256), representing 1.0. This allows a flow to respond quickly - * to congestion if the bottleneck is congested when the flow starts up. - */ -static u32 bbr_ecn_alpha_init = BBR_UNIT; /* 1.0, to respond quickly */ - -/* On ECN, cut inflight_lo to (1 - ecn_factor * ecn_alpha) scaled by BBR_SCALE. - * No ECN based bounding when 0. Max allwed value is 255. - */ -static u32 bbr_ecn_factor = BBR_UNIT * 1 / 3; /* 1/3 = 33% */ - -/* Estimate bw probing has gone too far if CE ratio exceeds this threshold. - * Scaled by BBR_SCALE. Disabled when 0. Max allowed is 255. - */ -static u32 bbr_ecn_thresh = BBR_UNIT * 1 / 2; /* 1/2 = 50% */ - -/* Max RTT (in usec) at which to use sender-side ECN logic. - * Disabled when 0 (ECN allowed at any RTT). - * Max allowed for the parameter is 524287 (0x7ffff) us, ~524 ms. - */ -static u32 bbr_ecn_max_rtt_us = 5000; - -/* If non-zero, if in a cycle with no losses but some ECN marks, after ECN - * clears then use a multiplicative increase to quickly reprobe bw by - * starting inflight probing at the given multiple of inflight_hi. - * Default for this experimental knob is 0 (disabled). - * Planned value for experiments: BBR_UNIT * 1 / 2 = 128, representing 0.5. - */ -static u32 bbr_ecn_reprobe_gain; - -/* Estimate bw probing has gone too far if loss rate exceeds this level. */ -static u32 bbr_loss_thresh = BBR_UNIT * 2 / 100; /* 2% loss */ - -/* Exit STARTUP if number of loss marking events in a Recovery round is >= N, - * and loss rate is higher than bbr_loss_thresh. - * Disabled if 0. Max allowed value is 15 (0xF). - */ -static u32 bbr_full_loss_cnt = 8; - -/* Exit STARTUP if number of round trips with ECN mark rate above ecn_thresh - * meets this count. Max allowed value is 3. - */ -static u32 bbr_full_ecn_cnt = 2; - -/* Fraction of unutilized headroom to try to leave in path upon high loss. */ -static u32 bbr_inflight_headroom = BBR_UNIT * 15 / 100; - -/* Multiplier to get target inflight (as multiple of BDP) for PROBE_UP phase. - * Default is 1.25x, as in BBR v1. Max allowed is 511. - */ -static u32 bbr_bw_probe_pif_gain = BBR_UNIT * 5 / 4; - -/* Multiplier to get Reno-style probe epoch duration as: k * BDP round trips. - * If zero, disables this BBR v2 Reno-style BDP-scaled coexistence mechanism. - * Max allowed is 511. - */ -static u32 bbr_bw_probe_reno_gain = BBR_UNIT; - -/* Max number of packet-timed rounds to wait before probing for bandwidth. If - * we want to tolerate 1% random loss per round, and not have this cut our - * inflight too much, we must probe for bw periodically on roughly this scale. - * If low, limits Reno/CUBIC coexistence; if high, limits loss tolerance. - * We aim to be fair with Reno/CUBIC up to a BDP of at least: - * BDP = 25Mbps * .030sec /(1514bytes) = 61.9 packets - */ -static u32 bbr_bw_probe_max_rounds = 63; - -/* Max amount of randomness to inject in round counting for Reno-coexistence. - * Max value is 15. - */ -static u32 bbr_bw_probe_rand_rounds = 2; - -/* Use BBR-native probe time scale starting at this many usec. - * We aim to be fair with Reno/CUBIC up to an inter-loss time epoch of at least: - * BDP*RTT = 25Mbps * .030sec /(1514bytes) * 0.030sec = 1.9 secs - */ -static u32 bbr_bw_probe_base_us = 2 * USEC_PER_SEC; /* 2 secs */ - -/* Use BBR-native probes spread over this many usec: */ -static u32 bbr_bw_probe_rand_us = 1 * USEC_PER_SEC; /* 1 secs */ - -/* Undo the model changes made in loss recovery if recovery was spurious? */ -static bool bbr_undo = true; - -/* Use fast path if app-limited, no loss/ECN, and target cwnd was reached? */ -static bool bbr_fast_path = true; /* default: enabled */ - -/* Use fast ack mode ? */ -static int bbr_fast_ack_mode = 1; /* default: rwnd check off */ - -/* How much to additively increase inflight_hi when entering REFILL? */ -static u32 bbr_refill_add_inc; /* default: disabled */ - -module_param_named(beta, bbr_beta, uint, 0644); -module_param_named(ecn_alpha_gain, bbr_ecn_alpha_gain, uint, 0644); -module_param_named(ecn_alpha_init, bbr_ecn_alpha_init, uint, 0644); -module_param_named(ecn_factor, bbr_ecn_factor, uint, 0644); -module_param_named(ecn_thresh, bbr_ecn_thresh, uint, 0644); -module_param_named(ecn_max_rtt_us, bbr_ecn_max_rtt_us, uint, 0644); -module_param_named(ecn_reprobe_gain, bbr_ecn_reprobe_gain, uint, 0644); -module_param_named(loss_thresh, bbr_loss_thresh, uint, 0664); -module_param_named(full_loss_cnt, bbr_full_loss_cnt, uint, 0664); -module_param_named(full_ecn_cnt, bbr_full_ecn_cnt, uint, 0664); -module_param_named(inflight_headroom, bbr_inflight_headroom, uint, 0664); -module_param_named(bw_probe_pif_gain, bbr_bw_probe_pif_gain, uint, 0664); -module_param_named(bw_probe_reno_gain, bbr_bw_probe_reno_gain, uint, 0664); -module_param_named(bw_probe_max_rounds, bbr_bw_probe_max_rounds, uint, 0664); -module_param_named(bw_probe_rand_rounds, bbr_bw_probe_rand_rounds, uint, 0664); -module_param_named(bw_probe_base_us, bbr_bw_probe_base_us, uint, 0664); -module_param_named(bw_probe_rand_us, bbr_bw_probe_rand_us, uint, 0664); -module_param_named(undo, bbr_undo, bool, 0664); -module_param_named(fast_path, bbr_fast_path, bool, 0664); -module_param_named(fast_ack_mode, bbr_fast_ack_mode, uint, 0664); -module_param_named(refill_add_inc, bbr_refill_add_inc, uint, 0664); - -static void bbr2_init(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - const struct net *net = sock_net(sk); - - bbr_init(sk); /* run shared init code for v1 and v2 */ - - /* BBR v2 parameters: */ - bbr->params.beta = min_t(u32, 0xFFU, bbr_beta); - bbr->params.ecn_alpha_gain = min_t(u32, 0xFFU, bbr_ecn_alpha_gain); - bbr->params.ecn_alpha_init = min_t(u32, BBR_UNIT, bbr_ecn_alpha_init); - bbr->params.ecn_factor = min_t(u32, 0xFFU, bbr_ecn_factor); - bbr->params.ecn_thresh = min_t(u32, 0xFFU, bbr_ecn_thresh); - bbr->params.ecn_max_rtt_us = min_t(u32, 0x7ffffU, bbr_ecn_max_rtt_us); - bbr->params.ecn_reprobe_gain = min_t(u32, 0x1FF, bbr_ecn_reprobe_gain); - bbr->params.loss_thresh = min_t(u32, 0xFFU, bbr_loss_thresh); - bbr->params.full_loss_cnt = min_t(u32, 0xFU, bbr_full_loss_cnt); - bbr->params.full_ecn_cnt = min_t(u32, 0x3U, bbr_full_ecn_cnt); - bbr->params.inflight_headroom = - min_t(u32, 0xFFU, bbr_inflight_headroom); - bbr->params.bw_probe_pif_gain = - min_t(u32, 0x1FFU, bbr_bw_probe_pif_gain); - bbr->params.bw_probe_reno_gain = - min_t(u32, 0x1FFU, bbr_bw_probe_reno_gain); - bbr->params.bw_probe_max_rounds = - min_t(u32, 0xFFU, bbr_bw_probe_max_rounds); - bbr->params.bw_probe_rand_rounds = - min_t(u32, 0xFU, bbr_bw_probe_rand_rounds); - bbr->params.bw_probe_base_us = - min_t(u32, (1 << 26) - 1, bbr_bw_probe_base_us); - bbr->params.bw_probe_rand_us = - min_t(u32, (1 << 26) - 1, bbr_bw_probe_rand_us); - bbr->params.undo = bbr_undo; - bbr->params.fast_path = bbr_fast_path ? 1 : 0; - bbr->params.refill_add_inc = min_t(u32, 0x3U, bbr_refill_add_inc); - - /* BBR v2 state: */ - bbr->initialized = 1; - /* Start sampling ECN mark rate after first full flight is ACKed: */ - bbr->loss_round_delivered = tp->delivered + 1; - bbr->loss_round_start = 0; - bbr->undo_bw_lo = 0; - bbr->undo_inflight_lo = 0; - bbr->undo_inflight_hi = 0; - bbr->loss_events_in_round = 0; - bbr->startup_ecn_rounds = 0; - bbr2_reset_congestion_signals(sk); - bbr->bw_lo = ~0U; - bbr->bw_hi[0] = 0; - bbr->bw_hi[1] = 0; - bbr->inflight_lo = ~0U; - bbr->inflight_hi = ~0U; - bbr->bw_probe_up_cnt = ~0U; - bbr->bw_probe_up_acks = 0; - bbr->bw_probe_up_rounds = 0; - bbr->probe_wait_us = 0; - bbr->stopped_risky_probe = 0; - bbr->ack_phase = BBR_ACKS_INIT; - bbr->rounds_since_probe = 0; - bbr->bw_probe_samples = 0; - bbr->prev_probe_too_high = 0; - bbr->ecn_eligible = 0; - bbr->ecn_alpha = bbr->params.ecn_alpha_init; - bbr->alpha_last_delivered = 0; - bbr->alpha_last_delivered_ce = 0; - - bbr->plb.enabled = 0; - bbr->plb.consec_cong_rounds = 0; - bbr->plb.pause_until = 0; - if ((tp->ecn_flags & TCP_ECN_OK) && - net->ipv4.sysctl_tcp_plb_enabled) - bbr->plb.enabled = 1; - - tp->fast_ack_mode = min_t(u32, 0x2U, bbr_fast_ack_mode); - - if ((tp->ecn_flags & TCP_ECN_OK) && bbr_ecn_enable) - tp->ecn_flags |= TCP_ECN_ECT_PERMANENT; -} - -/* Core TCP stack informs us that the given skb was just marked lost. */ -static void bbr2_skb_marked_lost(struct sock *sk, const struct sk_buff *skb) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - struct tcp_skb_cb *scb = TCP_SKB_CB(skb); - struct rate_sample rs; - - /* Capture "current" data over the full round trip of loss, - * to have a better chance to see the full capacity of the path. - */ - if (!bbr->loss_in_round) /* first loss in this round trip? */ - bbr->loss_round_delivered = tp->delivered; /* set round trip */ - bbr->loss_in_round = 1; - bbr->loss_in_cycle = 1; - - if (!bbr->bw_probe_samples) - return; /* not an skb sent while probing for bandwidth */ - if (unlikely(!scb->tx.delivered_mstamp)) - return; /* skb was SACKed, reneged, marked lost; ignore it */ - /* We are probing for bandwidth. Construct a rate sample that - * estimates what happened in the flight leading up to this lost skb, - * then see if the loss rate went too high, and if so at which packet. - */ - memset(&rs, 0, sizeof(rs)); - rs.tx_in_flight = scb->tx.in_flight; - rs.lost = tp->lost - scb->tx.lost; - rs.is_app_limited = scb->tx.is_app_limited; - if (bbr2_is_inflight_too_high(sk, &rs)) { - rs.tx_in_flight = bbr2_inflight_hi_from_lost_skb(sk, &rs, skb); - bbr2_handle_inflight_too_high(sk, &rs); - } -} - -/* Revert short-term model if current loss recovery event was spurious. */ -static u32 bbr2_undo_cwnd(struct sock *sk) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - bbr->debug.undo = 1; - bbr->full_bw = 0; /* spurious slow-down; reset full pipe detection */ - bbr->full_bw_cnt = 0; - bbr->loss_in_round = 0; - - if (!bbr->params.undo) - return tp->snd_cwnd; - - /* Revert to cwnd and other state saved before loss episode. */ - bbr->bw_lo = max(bbr->bw_lo, bbr->undo_bw_lo); - bbr->inflight_lo = max(bbr->inflight_lo, bbr->undo_inflight_lo); - bbr->inflight_hi = max(bbr->inflight_hi, bbr->undo_inflight_hi); - return bbr->prior_cwnd; -} - -/* Entering loss recovery, so save state for when we undo recovery. */ -static u32 bbr2_ssthresh(struct sock *sk) -{ - struct bbr *bbr = inet_csk_ca(sk); - - bbr_save_cwnd(sk); - /* For undo, save state that adapts based on loss signal. */ - bbr->undo_bw_lo = bbr->bw_lo; - bbr->undo_inflight_lo = bbr->inflight_lo; - bbr->undo_inflight_hi = bbr->inflight_hi; - return tcp_sk(sk)->snd_ssthresh; -} - -static enum tcp_bbr2_phase bbr2_get_phase(struct bbr *bbr) -{ - switch (bbr->mode) { - case BBR_STARTUP: - return BBR2_PHASE_STARTUP; - case BBR_DRAIN: - return BBR2_PHASE_DRAIN; - case BBR_PROBE_BW: - break; - case BBR_PROBE_RTT: - return BBR2_PHASE_PROBE_RTT; - default: - return BBR2_PHASE_INVALID; - } - switch (bbr->cycle_idx) { - case BBR_BW_PROBE_UP: - return BBR2_PHASE_PROBE_BW_UP; - case BBR_BW_PROBE_DOWN: - return BBR2_PHASE_PROBE_BW_DOWN; - case BBR_BW_PROBE_CRUISE: - return BBR2_PHASE_PROBE_BW_CRUISE; - case BBR_BW_PROBE_REFILL: - return BBR2_PHASE_PROBE_BW_REFILL; - default: - return BBR2_PHASE_INVALID; - } -} - -static size_t bbr2_get_info(struct sock *sk, u32 ext, int *attr, - union tcp_cc_info *info) -{ - if (ext & (1 << (INET_DIAG_BBRINFO - 1)) || - ext & (1 << (INET_DIAG_VEGASINFO - 1))) { - struct bbr *bbr = inet_csk_ca(sk); - u64 bw = bbr_bw_bytes_per_sec(sk, bbr_bw(sk)); - u64 bw_hi = bbr_bw_bytes_per_sec(sk, bbr_max_bw(sk)); - u64 bw_lo = bbr->bw_lo == ~0U ? - ~0ULL : bbr_bw_bytes_per_sec(sk, bbr->bw_lo); - - memset(&info->bbr2, 0, sizeof(info->bbr2)); - info->bbr2.bbr_bw_lsb = (u32)bw; - info->bbr2.bbr_bw_msb = (u32)(bw >> 32); - info->bbr2.bbr_min_rtt = bbr->min_rtt_us; - info->bbr2.bbr_pacing_gain = bbr->pacing_gain; - info->bbr2.bbr_cwnd_gain = bbr->cwnd_gain; - info->bbr2.bbr_bw_hi_lsb = (u32)bw_hi; - info->bbr2.bbr_bw_hi_msb = (u32)(bw_hi >> 32); - info->bbr2.bbr_bw_lo_lsb = (u32)bw_lo; - info->bbr2.bbr_bw_lo_msb = (u32)(bw_lo >> 32); - info->bbr2.bbr_mode = bbr->mode; - info->bbr2.bbr_phase = (__u8)bbr2_get_phase(bbr); - info->bbr2.bbr_version = (__u8)2; - info->bbr2.bbr_inflight_lo = bbr->inflight_lo; - info->bbr2.bbr_inflight_hi = bbr->inflight_hi; - info->bbr2.bbr_extra_acked = bbr_extra_acked(sk); - *attr = INET_DIAG_BBRINFO; - return sizeof(info->bbr2); - } - return 0; -} - -static void bbr2_set_state(struct sock *sk, u8 new_state) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct bbr *bbr = inet_csk_ca(sk); - - if (new_state == TCP_CA_Loss) { - struct rate_sample rs = { .losses = 1 }; - struct bbr_context ctx = { 0 }; - - tcp_plb_update_state_upon_rto(sk, &bbr->plb); - bbr->prev_ca_state = TCP_CA_Loss; - bbr->full_bw = 0; - if (!bbr2_is_probing_bandwidth(sk) && bbr->inflight_lo == ~0U) { - /* bbr_adapt_lower_bounds() needs cwnd before - * we suffered an RTO, to update inflight_lo: - */ - bbr->inflight_lo = - max(tp->snd_cwnd, bbr->prior_cwnd); - } - bbr_debug(sk, 0, &rs, &ctx); - } else if (bbr->prev_ca_state == TCP_CA_Loss && - new_state != TCP_CA_Loss) { - tp->snd_cwnd = max(tp->snd_cwnd, bbr->prior_cwnd); - bbr->try_fast_path = 0; /* bound cwnd using latest model */ - } -} - -static struct tcp_congestion_ops tcp_bbr2_cong_ops __read_mostly = { - .flags = TCP_CONG_NON_RESTRICTED | TCP_CONG_WANTS_CE_EVENTS, - .name = "bbr2", - .owner = THIS_MODULE, - .init = bbr2_init, - .cong_control = bbr2_main, - .sndbuf_expand = bbr_sndbuf_expand, - .skb_marked_lost = bbr2_skb_marked_lost, - .undo_cwnd = bbr2_undo_cwnd, - .cwnd_event = bbr_cwnd_event, - .ssthresh = bbr2_ssthresh, - .tso_segs = bbr_tso_segs, - .get_info = bbr2_get_info, - .set_state = bbr2_set_state, -}; - -static int __init bbr_register(void) -{ - BUILD_BUG_ON(sizeof(struct bbr) > ICSK_CA_PRIV_SIZE); - return tcp_register_congestion_control(&tcp_bbr2_cong_ops); -} - -static void __exit bbr_unregister(void) -{ - tcp_unregister_congestion_control(&tcp_bbr2_cong_ops); -} - -module_init(bbr_register); -module_exit(bbr_unregister); - -MODULE_AUTHOR("Van Jacobson "); -MODULE_AUTHOR("Neal Cardwell "); -MODULE_AUTHOR("Yuchung Cheng "); -MODULE_AUTHOR("Soheil Hassas Yeganeh "); -MODULE_AUTHOR("Priyaranjan Jha "); -MODULE_AUTHOR("Yousuk Seung "); -MODULE_AUTHOR("Kevin Yang "); -MODULE_AUTHOR("Arjun Roy "); - -MODULE_LICENSE("Dual BSD/GPL"); -MODULE_DESCRIPTION("TCP BBR (Bottleneck Bandwidth and RTT)"); diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c index 0f268f2ff2e9a..d3cae40749e87 100644 --- a/net/ipv4/tcp_cong.c +++ b/net/ipv4/tcp_cong.c @@ -189,7 +189,6 @@ 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 4ae71702e1660..00e654962a157 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -349,7 +349,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) tcp_enter_quickack_mode(sk, 2); break; case INET_ECN_CE: - if (tcp_ca_wants_ce_events(sk)) + if (tcp_ca_needs_ecn(sk)) tcp_ca_event(sk, CA_EVENT_ECN_IS_CE); if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) { @@ -360,7 +360,7 @@ static void __tcp_ecn_check_ce(struct sock *sk, const struct sk_buff *skb) tp->ecn_flags |= TCP_ECN_SEEN; break; default: - if (tcp_ca_wants_ce_events(sk)) + if (tcp_ca_needs_ecn(sk)) tcp_ca_event(sk, CA_EVENT_ECN_NO_CE); tp->ecn_flags |= TCP_ECN_SEEN; break; @@ -1079,12 +1079,7 @@ 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) @@ -1465,17 +1460,6 @@ 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 @@ -3834,7 +3818,6 @@ 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. @@ -3933,7 +3916,6 @@ 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); @@ -5569,14 +5551,13 @@ 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_ipv4.c b/net/ipv4/tcp_ipv4.c index 928f4f257bb03..dc94e187e919d 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -3213,13 +3213,6 @@ static int __net_init tcp_sk_init(struct net *net) net->ipv4.sysctl_tcp_fastopen_blackhole_timeout = 0; atomic_set(&net->ipv4.tfo_active_disable_times, 0); - /* Set default values for PLB */ - net->ipv4.sysctl_tcp_plb_enabled = 0; /* Disabled by default */ - net->ipv4.sysctl_tcp_plb_cong_thresh = 128; /* 50% congestion */ - net->ipv4.sysctl_tcp_plb_idle_rehash_rounds = 3; - net->ipv4.sysctl_tcp_plb_rehash_rounds = 12; - net->ipv4.sysctl_tcp_plb_suspend_rto_sec = 60; - /* Reno is always built in */ if (!net_eq(net, &init_net) && bpf_try_module_get(init_net.ipv4.tcp_congestion_control, diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c6c42fbe556f1..380a1952dfd66 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -379,8 +379,7 @@ 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 (!(tp->ecn_flags & TCP_ECN_ECT_PERMANENT) && - !tcp_ca_needs_ecn(sk)) { + } else if (!tcp_ca_needs_ecn(sk)) { /* ACK or retransmitted segment: clear ECT|CE */ INET_ECN_dontxmit(sk); } @@ -1538,7 +1537,7 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, { struct tcp_sock *tp = tcp_sk(sk); struct sk_buff *buff; - int nsize, old_factor, inflight_prev; + int nsize, old_factor; long limit; int nlen; u8 flags; @@ -1615,15 +1614,6 @@ int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, if (diff) tcp_adjust_pcount(sk, skb, diff); - - /* Set buff tx.in_flight as if buff were sent by itself. */ - inflight_prev = TCP_SKB_CB(skb)->tx.in_flight - old_factor; - if (WARN_ONCE(inflight_prev < 0, - "inconsistent: tx.in_flight: %u old_factor: %d", - TCP_SKB_CB(skb)->tx.in_flight, old_factor)) - inflight_prev = 0; - TCP_SKB_CB(buff)->tx.in_flight = inflight_prev + - tcp_skb_pcount(buff); } /* Link BUFF into the send queue. */ @@ -2007,12 +1997,13 @@ 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 tso_segs; + 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); - tso_segs = ca_ops->tso_segs ? - ca_ops->tso_segs(sk, mss_now) : - tcp_tso_autosize(sk, mss_now, - READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_min_tso_segs)); + tso_segs = tcp_tso_autosize(sk, mss_now, min_tso); return min_t(u32, tso_segs, sk->sk_gso_max_segs); } @@ -2648,7 +2639,6 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, skb_set_delivery_time(skb, tp->tcp_wstamp_ns, true); list_move_tail(&skb->tcp_tsorted_anchor, &tp->tsorted_sent_queue); tcp_init_tso_segs(skb, mss_now); - tcp_set_tx_in_flight(sk, skb); goto repair; /* Skip network transmission */ } diff --git a/net/ipv4/tcp_plb.c b/net/ipv4/tcp_plb.c deleted file mode 100644 index 71b02c0404cea..0000000000000 --- a/net/ipv4/tcp_plb.c +++ /dev/null @@ -1,100 +0,0 @@ -/* Protective Load Balancing (PLB) - * - * PLB was designed to reduce link load imbalance across datacenter - * switches. PLB is a host-based optimization; it leverages congestion - * signals from the transport layer to randomly change the path of the - * connection experiencing sustained congestion. PLB prefers to repath - * after idle periods to minimize packet reordering. It repaths by - * changing the IPv6 Flow Label on the packets of a connection, which - * datacenter switches include as part of ECMP/WCMP hashing. - * - * PLB is described in detail in: - * - * Mubashir Adnan Qureshi, Yuchung Cheng, Qianwen Yin, Qiaobin Fu, - * Gautam Kumar, Masoud Moshref, Junhua Yan, Van Jacobson, - * David Wetherall,Abdul Kabbani: - * "PLB: Congestion Signals are Simple and Effective for - * Network Load Balancing" - * In ACM SIGCOMM 2022, Amsterdam Netherlands. - * - */ - -#include - -/* Called once per round-trip to update PLB state for a connection. */ -void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb, - const int cong_ratio) -{ - struct net *net = sock_net(sk); - - if (!plb->enabled) - return; - - if (cong_ratio >= 0) { - if (cong_ratio < net->ipv4.sysctl_tcp_plb_cong_thresh) - plb->consec_cong_rounds = 0; - else if (plb->consec_cong_rounds < - net->ipv4.sysctl_tcp_plb_rehash_rounds) - plb->consec_cong_rounds++; - } -} -EXPORT_SYMBOL_GPL(tcp_plb_update_state); - -/* Check whether recent congestion has been persistent enough to warrant - * a load balancing decision that switches the connection to another path. - */ -void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb) -{ - struct net *net = sock_net(sk); - bool can_idle_rehash, can_force_rehash; - - if (!plb->enabled) - return; - - /* Note that tcp_jiffies32 can wrap, so we clear pause_until - * to 0 to indicate there is no recent RTO event that constrains - * PLB rehashing. - */ - if (plb->pause_until && - !before(tcp_jiffies32, plb->pause_until)) - plb->pause_until = 0; - - can_idle_rehash = net->ipv4.sysctl_tcp_plb_idle_rehash_rounds && - !tcp_sk(sk)->packets_out && - plb->consec_cong_rounds >= - net->ipv4.sysctl_tcp_plb_idle_rehash_rounds; - can_force_rehash = plb->consec_cong_rounds >= - net->ipv4.sysctl_tcp_plb_rehash_rounds; - - if (!plb->pause_until && (can_idle_rehash || can_force_rehash)) { - sk_rethink_txhash(sk); - plb->consec_cong_rounds = 0; - tcp_sk(sk)->ecn_rehash++; - NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPECNREHASH); - } -} -EXPORT_SYMBOL_GPL(tcp_plb_check_rehash); - -/* Upon RTO, disallow load balancing for a while, to avoid having load - * balancing decisions switch traffic to a black-holed path that was - * previously avoided with a sk_rethink_txhash() call at RTO time. - */ -void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb) -{ - struct net *net = sock_net(sk); - u32 pause; - - if (!plb->enabled) - return; - - pause = net->ipv4.sysctl_tcp_plb_suspend_rto_sec * HZ; - pause += prandom_u32_max(pause); - plb->pause_until = tcp_jiffies32 + pause; - - /* Reset PLB state upon RTO, since an RTO causes a sk_rethink_txhash() call - * that may switch this connection to a path with completely different - * congestion characteristics. - */ - plb->consec_cong_rounds = 0; -} -EXPORT_SYMBOL_GPL(tcp_plb_update_state_upon_rto); diff --git a/net/ipv4/tcp_rate.c b/net/ipv4/tcp_rate.c index a8b4c95045701..a8f6d9d06f2eb 100644 --- a/net/ipv4/tcp_rate.c +++ b/net/ipv4/tcp_rate.c @@ -34,24 +34,6 @@ * 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(). */ @@ -84,9 +66,7 @@ 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) @@ -111,21 +91,18 @@ void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, if (!rs->prior_delivered || tcp_skb_sent_after(tx_tstamp, tp->first_tx_mstamp, scb->end_seq, rs->last_end_seq)) { - rs->prior_lost = scb->tx.lost; rs->prior_delivered_ce = scb->tx.delivered_ce; rs->prior_delivered = scb->tx.delivered; rs->prior_mstamp = scb->tx.delivered_mstamp; rs->is_app_limited = scb->tx.is_app_limited; rs->is_retrans = scb->sacked & TCPCB_RETRANS; rs->last_end_seq = scb->end_seq; - rs->tx_in_flight = scb->tx.in_flight; /* Record send time of most recently ACKed packet: */ tp->first_tx_mstamp = tx_tstamp; /* Find the duration of the "send phase" of this window: */ - rs->interval_us = tcp_stamp32_us_delta( - tp->first_tx_mstamp, - scb->tx.first_tx_mstamp); + rs->interval_us = tcp_stamp_us_delta(tp->first_tx_mstamp, + scb->tx.first_tx_mstamp); } /* Mark off the skb delivered once it's sacked to avoid being @@ -167,7 +144,6 @@ 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 */ @@ -179,7 +155,7 @@ void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, * longer phase. */ snd_us = rs->interval_us; /* send phase */ - ack_us = tcp_stamp32_us_delta(tp->tcp_mstamp, + ack_us = tcp_stamp_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 c2bc56da653cb..0b5d0a2867a8c 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -615,7 +615,6 @@ 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;