// SPDX-License-Identifier: GPL-2.0-only /* * TCP CUBIC: Binary Increase Congestion control for TCP v2.3 * Home page: * http://netsrv.csc.ncsu.edu/twiki/bin/view/Main/BIC * This is from the implementation of CUBIC TCP in * Sangtae Ha, Injong Rhee and Lisong Xu, * "CUBIC: A New TCP-Friendly High-Speed TCP Variant" * in ACM SIGOPS Operating System Review, July 2008. * Available from: * http://netsrv.csc.ncsu.edu/export/cubic_a_new_tcp_2008.pdf * * CUBIC integrates a new slow start algorithm, called HyStart. * The details of HyStart are presented in * Sangtae Ha and Injong Rhee, * "Taming the Elephants: New TCP Slow Start", NCSU TechReport 2008. * Available from: * http://netsrv.csc.ncsu.edu/export/hystart_techreport_2008.pdf * * All testing results are available from: * http://netsrv.csc.ncsu.edu/wiki/index.php/TCP_Testing * * Unless CUBIC is enabled and congestion window is large * this behaves the same as the original Reno. */ #include <linux/mm.h> #include <linux/btf.h> #include <linux/btf_ids.h> #include <linux/module.h> #include <linux/math64.h> #include <net/tcp.h> #define BICTCP_BETA_SCALE … #define BICTCP_HZ … /* Two methods of hybrid slow start */ #define HYSTART_ACK_TRAIN … #define HYSTART_DELAY … /* Number of delay samples for detecting the increase of delay */ #define HYSTART_MIN_SAMPLES … #define HYSTART_DELAY_MIN … #define HYSTART_DELAY_MAX … #define HYSTART_DELAY_THRESH(x) … static int fast_convergence __read_mostly = …; static int beta __read_mostly = …; /* = 717/1024 (BICTCP_BETA_SCALE) */ static int initial_ssthresh __read_mostly; static int bic_scale __read_mostly = …; static int tcp_friendliness __read_mostly = …; static int hystart __read_mostly = …; static int hystart_detect __read_mostly = …; static int hystart_low_window __read_mostly = …; static int hystart_ack_delta_us __read_mostly = …; static u32 cube_rtt_scale __read_mostly; static u32 beta_scale __read_mostly; static u64 cube_factor __read_mostly; /* Note parameters that are used for precomputing scale factors are read-only */ module_param(fast_convergence, int, 0644); MODULE_PARM_DESC(…) …; module_param(beta, int, 0644); MODULE_PARM_DESC(…) …; module_param(initial_ssthresh, int, 0644); MODULE_PARM_DESC(…) …; module_param(bic_scale, int, 0444); MODULE_PARM_DESC(…) …; module_param(tcp_friendliness, int, 0644); MODULE_PARM_DESC(…) …; module_param(hystart, int, 0644); MODULE_PARM_DESC(…) …; module_param(hystart_detect, int, 0644); MODULE_PARM_DESC(…) …; module_param(hystart_low_window, int, 0644); MODULE_PARM_DESC(…) …; module_param(hystart_ack_delta_us, int, 0644); MODULE_PARM_DESC(…) …; /* BIC TCP Parameters */ struct bictcp { … }; static inline void bictcp_reset(struct bictcp *ca) { … } static inline u32 bictcp_clock_us(const struct sock *sk) { … } static inline void bictcp_hystart_reset(struct sock *sk) { … } __bpf_kfunc static void cubictcp_init(struct sock *sk) { … } __bpf_kfunc static void cubictcp_cwnd_event(struct sock *sk, enum tcp_ca_event event) { … } /* calculate the cubic root of x using a table lookup followed by one * Newton-Raphson iteration. * Avg err ~= 0.195% */ static u32 cubic_root(u64 a) { … } /* * Compute congestion window to use. */ static inline void bictcp_update(struct bictcp *ca, u32 cwnd, u32 acked) { … } __bpf_kfunc static void cubictcp_cong_avoid(struct sock *sk, u32 ack, u32 acked) { … } __bpf_kfunc static u32 cubictcp_recalc_ssthresh(struct sock *sk) { … } __bpf_kfunc static void cubictcp_state(struct sock *sk, u8 new_state) { … } /* Account for TSO/GRO delays. * Otherwise short RTT flows could get too small ssthresh, since during * slow start we begin with small TSO packets and ca->delay_min would * not account for long aggregation delay when TSO packets get bigger. * Ideally even with a very small RTT we would like to have at least one * TSO packet being sent and received by GRO, and another one in qdisc layer. * We apply another 100% factor because @rate is doubled at this point. * We cap the cushion to 1ms. */ static u32 hystart_ack_delay(const struct sock *sk) { … } static void hystart_update(struct sock *sk, u32 delay) { … } __bpf_kfunc static void cubictcp_acked(struct sock *sk, const struct ack_sample *sample) { … } static struct tcp_congestion_ops cubictcp __read_mostly = …; BTF_KFUNCS_START(tcp_cubic_check_kfunc_ids) BTF_ID_FLAGS(…) BTF_ID_FLAGS(…) BTF_ID_FLAGS(…) BTF_ID_FLAGS(…) BTF_ID_FLAGS(…) BTF_ID_FLAGS(…) BTF_KFUNCS_END(…) static const struct btf_kfunc_id_set tcp_cubic_kfunc_set = …; static int __init cubictcp_register(void) { … } static void __exit cubictcp_unregister(void) { … } module_init(…) …; module_exit(cubictcp_unregister); MODULE_AUTHOR(…) …; MODULE_LICENSE(…) …; MODULE_DESCRIPTION(…) …; MODULE_VERSION(…) …;
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