| Author | Tokens | Token Proportion | Commits | Commit Proportion |
|---|---|---|---|---|
| Baruch Even | 1308 | 86.62% | 4 | 19.05% |
| Arnaldo Carvalho de Melo | 93 | 6.16% | 1 | 4.76% |
| Stephen Hemminger | 34 | 2.25% | 5 | 23.81% |
| Doug Leith | 28 | 1.85% | 1 | 4.76% |
| Lawrence Brakmo | 15 | 0.99% | 1 | 4.76% |
| Ilpo Järvinen | 13 | 0.86% | 1 | 4.76% |
| Yuchung Cheng | 8 | 0.53% | 3 | 14.29% |
| David S. Miller | 7 | 0.46% | 1 | 4.76% |
| Thomas Gleixner | 1 | 0.07% | 1 | 4.76% |
| Eric Dumazet | 1 | 0.07% | 1 | 4.76% |
| Alexey Dobriyan | 1 | 0.07% | 1 | 4.76% |
| Gavin McCullagh | 1 | 0.07% | 1 | 4.76% |
| Total | 1510 | 21 |
// SPDX-License-Identifier: GPL-2.0-only /* * H-TCP congestion control. The algorithm is detailed in: * R.N.Shorten, D.J.Leith: * "H-TCP: TCP for high-speed and long-distance networks" * Proc. PFLDnet, Argonne, 2004. * http://www.hamilton.ie/net/htcp3.pdf */ #include <linux/mm.h> #include <linux/module.h> #include <net/tcp.h> #define ALPHA_BASE (1<<7) /* 1.0 with shift << 7 */ #define BETA_MIN (1<<6) /* 0.5 with shift << 7 */ #define BETA_MAX 102 /* 0.8 with shift << 7 */ static int use_rtt_scaling __read_mostly = 1; module_param(use_rtt_scaling, int, 0644); MODULE_PARM_DESC(use_rtt_scaling, "turn on/off RTT scaling"); static int use_bandwidth_switch __read_mostly = 1; module_param(use_bandwidth_switch, int, 0644); MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher"); struct htcp { u32 alpha; /* Fixed point arith, << 7 */ u8 beta; /* Fixed point arith, << 7 */ u8 modeswitch; /* Delay modeswitch until we had at least one congestion event */ u16 pkts_acked; u32 packetcount; u32 minRTT; u32 maxRTT; u32 last_cong; /* Time since last congestion event end */ u32 undo_last_cong; u32 undo_maxRTT; u32 undo_old_maxB; /* Bandwidth estimation */ u32 minB; u32 maxB; u32 old_maxB; u32 Bi; u32 lasttime; }; static inline u32 htcp_cong_time(const struct htcp *ca) { return jiffies - ca->last_cong; } static inline u32 htcp_ccount(const struct htcp *ca) { return htcp_cong_time(ca) / ca->minRTT; } static inline void htcp_reset(struct htcp *ca) { ca->undo_last_cong = ca->last_cong; ca->undo_maxRTT = ca->maxRTT; ca->undo_old_maxB = ca->old_maxB; ca->last_cong = jiffies; } static u32 htcp_cwnd_undo(struct sock *sk) { struct htcp *ca = inet_csk_ca(sk); if (ca->undo_last_cong) { ca->last_cong = ca->undo_last_cong; ca->maxRTT = ca->undo_maxRTT; ca->old_maxB = ca->undo_old_maxB; ca->undo_last_cong = 0; } return tcp_reno_undo_cwnd(sk); } static inline void measure_rtt(struct sock *sk, u32 srtt) { const struct inet_connection_sock *icsk = inet_csk(sk); struct htcp *ca = inet_csk_ca(sk); /* keep track of minimum RTT seen so far, minRTT is zero at first */ if (ca->minRTT > srtt || !ca->minRTT) ca->minRTT = srtt; /* max RTT */ if (icsk->icsk_ca_state == TCP_CA_Open) { if (ca->maxRTT < ca->minRTT) ca->maxRTT = ca->minRTT; if (ca->maxRTT < srtt && srtt <= ca->maxRTT + msecs_to_jiffies(20)) ca->maxRTT = srtt; } } static void measure_achieved_throughput(struct sock *sk, const struct ack_sample *sample) { const struct inet_connection_sock *icsk = inet_csk(sk); const struct tcp_sock *tp = tcp_sk(sk); struct htcp *ca = inet_csk_ca(sk); u32 now = tcp_jiffies32; if (icsk->icsk_ca_state == TCP_CA_Open) ca->pkts_acked = sample->pkts_acked; if (sample->rtt_us > 0) measure_rtt(sk, usecs_to_jiffies(sample->rtt_us)); if (!use_bandwidth_switch) return; /* achieved throughput calculations */ if (!((1 << icsk->icsk_ca_state) & (TCPF_CA_Open | TCPF_CA_Disorder))) { ca->packetcount = 0; ca->lasttime = now; return; } ca->packetcount += sample->pkts_acked; if (ca->packetcount >= tp->snd_cwnd - (ca->alpha >> 7 ? : 1) && now - ca->lasttime >= ca->minRTT && ca->minRTT > 0) { __u32 cur_Bi = ca->packetcount * HZ / (now - ca->lasttime); if (htcp_ccount(ca) <= 3) { /* just after backoff */ ca->minB = ca->maxB = ca->Bi = cur_Bi; } else { ca->Bi = (3 * ca->Bi + cur_Bi) / 4; if (ca->Bi > ca->maxB) ca->maxB = ca->Bi; if (ca->minB > ca->maxB) ca->minB = ca->maxB; } ca->packetcount = 0; ca->lasttime = now; } } static inline void htcp_beta_update(struct htcp *ca, u32 minRTT, u32 maxRTT) { if (use_bandwidth_switch) { u32 maxB = ca->maxB; u32 old_maxB = ca->old_maxB; ca->old_maxB = ca->maxB; if (!between(5 * maxB, 4 * old_maxB, 6 * old_maxB)) { ca->beta = BETA_MIN; ca->modeswitch = 0; return; } } if (ca->modeswitch && minRTT > msecs_to_jiffies(10) && maxRTT) { ca->beta = (minRTT << 7) / maxRTT; if (ca->beta < BETA_MIN) ca->beta = BETA_MIN; else if (ca->beta > BETA_MAX) ca->beta = BETA_MAX; } else { ca->beta = BETA_MIN; ca->modeswitch = 1; } } static inline void htcp_alpha_update(struct htcp *ca) { u32 minRTT = ca->minRTT; u32 factor = 1; u32 diff = htcp_cong_time(ca); if (diff > HZ) { diff -= HZ; factor = 1 + (10 * diff + ((diff / 2) * (diff / 2) / HZ)) / HZ; } if (use_rtt_scaling && minRTT) { u32 scale = (HZ << 3) / (10 * minRTT); /* clamping ratio to interval [0.5,10]<<3 */ scale = min(max(scale, 1U << 2), 10U << 3); factor = (factor << 3) / scale; if (!factor) factor = 1; } ca->alpha = 2 * factor * ((1 << 7) - ca->beta); if (!ca->alpha) ca->alpha = ALPHA_BASE; } /* * After we have the rtt data to calculate beta, we'd still prefer to wait one * rtt before we adjust our beta to ensure we are working from a consistent * data. * * This function should be called when we hit a congestion event since only at * that point do we really have a real sense of maxRTT (the queues en route * were getting just too full now). */ static void htcp_param_update(struct sock *sk) { struct htcp *ca = inet_csk_ca(sk); u32 minRTT = ca->minRTT; u32 maxRTT = ca->maxRTT; htcp_beta_update(ca, minRTT, maxRTT); htcp_alpha_update(ca); /* add slowly fading memory for maxRTT to accommodate routing changes */ if (minRTT > 0 && maxRTT > minRTT) ca->maxRTT = minRTT + ((maxRTT - minRTT) * 95) / 100; } static u32 htcp_recalc_ssthresh(struct sock *sk) { const struct tcp_sock *tp = tcp_sk(sk); const struct htcp *ca = inet_csk_ca(sk); htcp_param_update(sk); return max((tp->snd_cwnd * ca->beta) >> 7, 2U); } static void htcp_cong_avoid(struct sock *sk, u32 ack, u32 acked) { struct tcp_sock *tp = tcp_sk(sk); struct htcp *ca = inet_csk_ca(sk); if (!tcp_is_cwnd_limited(sk)) return; if (tcp_in_slow_start(tp)) tcp_slow_start(tp, acked); else { /* In dangerous area, increase slowly. * In theory this is tp->snd_cwnd += alpha / tp->snd_cwnd */ if ((tp->snd_cwnd_cnt * ca->alpha)>>7 >= tp->snd_cwnd) { if (tp->snd_cwnd < tp->snd_cwnd_clamp) tp->snd_cwnd++; tp->snd_cwnd_cnt = 0; htcp_alpha_update(ca); } else tp->snd_cwnd_cnt += ca->pkts_acked; ca->pkts_acked = 1; } } static void htcp_init(struct sock *sk) { struct htcp *ca = inet_csk_ca(sk); memset(ca, 0, sizeof(struct htcp)); ca->alpha = ALPHA_BASE; ca->beta = BETA_MIN; ca->pkts_acked = 1; ca->last_cong = jiffies; } static void htcp_state(struct sock *sk, u8 new_state) { switch (new_state) { case TCP_CA_Open: { struct htcp *ca = inet_csk_ca(sk); if (ca->undo_last_cong) { ca->last_cong = jiffies; ca->undo_last_cong = 0; } } break; case TCP_CA_CWR: case TCP_CA_Recovery: case TCP_CA_Loss: htcp_reset(inet_csk_ca(sk)); break; } } static struct tcp_congestion_ops htcp __read_mostly = { .init = htcp_init, .ssthresh = htcp_recalc_ssthresh, .cong_avoid = htcp_cong_avoid, .set_state = htcp_state, .undo_cwnd = htcp_cwnd_undo, .pkts_acked = measure_achieved_throughput, .owner = THIS_MODULE, .name = "htcp", }; static int __init htcp_register(void) { BUILD_BUG_ON(sizeof(struct htcp) > ICSK_CA_PRIV_SIZE); BUILD_BUG_ON(BETA_MIN >= BETA_MAX); return tcp_register_congestion_control(&htcp); } static void __exit htcp_unregister(void) { tcp_unregister_congestion_control(&htcp); } module_init(htcp_register); module_exit(htcp_unregister); MODULE_AUTHOR("Baruch Even"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("H-TCP");