diff options
Diffstat (limited to 'net/ipv4/tcp_highspeed.c')
| -rw-r--r-- | net/ipv4/tcp_highspeed.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/net/ipv4/tcp_highspeed.c b/net/ipv4/tcp_highspeed.c new file mode 100644 index 000000000..c6de5ce79 --- /dev/null +++ b/net/ipv4/tcp_highspeed.c @@ -0,0 +1,186 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Sally Floyd's High Speed TCP (RFC 3649) congestion control + * + * See https://www.icir.org/floyd/hstcp.html + * + * John Heffner <jheffner@psc.edu> + */ + +#include <linux/module.h> +#include <net/tcp.h> + +/* From AIMD tables from RFC 3649 appendix B, + * with fixed-point MD scaled <<8. + */ +static const struct hstcp_aimd_val { + unsigned int cwnd; + unsigned int md; +} hstcp_aimd_vals[] = { + { 38, 128, /* 0.50 */ }, + { 118, 112, /* 0.44 */ }, + { 221, 104, /* 0.41 */ }, + { 347, 98, /* 0.38 */ }, + { 495, 93, /* 0.37 */ }, + { 663, 89, /* 0.35 */ }, + { 851, 86, /* 0.34 */ }, + { 1058, 83, /* 0.33 */ }, + { 1284, 81, /* 0.32 */ }, + { 1529, 78, /* 0.31 */ }, + { 1793, 76, /* 0.30 */ }, + { 2076, 74, /* 0.29 */ }, + { 2378, 72, /* 0.28 */ }, + { 2699, 71, /* 0.28 */ }, + { 3039, 69, /* 0.27 */ }, + { 3399, 68, /* 0.27 */ }, + { 3778, 66, /* 0.26 */ }, + { 4177, 65, /* 0.26 */ }, + { 4596, 64, /* 0.25 */ }, + { 5036, 62, /* 0.25 */ }, + { 5497, 61, /* 0.24 */ }, + { 5979, 60, /* 0.24 */ }, + { 6483, 59, /* 0.23 */ }, + { 7009, 58, /* 0.23 */ }, + { 7558, 57, /* 0.22 */ }, + { 8130, 56, /* 0.22 */ }, + { 8726, 55, /* 0.22 */ }, + { 9346, 54, /* 0.21 */ }, + { 9991, 53, /* 0.21 */ }, + { 10661, 52, /* 0.21 */ }, + { 11358, 52, /* 0.20 */ }, + { 12082, 51, /* 0.20 */ }, + { 12834, 50, /* 0.20 */ }, + { 13614, 49, /* 0.19 */ }, + { 14424, 48, /* 0.19 */ }, + { 15265, 48, /* 0.19 */ }, + { 16137, 47, /* 0.19 */ }, + { 17042, 46, /* 0.18 */ }, + { 17981, 45, /* 0.18 */ }, + { 18955, 45, /* 0.18 */ }, + { 19965, 44, /* 0.17 */ }, + { 21013, 43, /* 0.17 */ }, + { 22101, 43, /* 0.17 */ }, + { 23230, 42, /* 0.17 */ }, + { 24402, 41, /* 0.16 */ }, + { 25618, 41, /* 0.16 */ }, + { 26881, 40, /* 0.16 */ }, + { 28193, 39, /* 0.16 */ }, + { 29557, 39, /* 0.15 */ }, + { 30975, 38, /* 0.15 */ }, + { 32450, 38, /* 0.15 */ }, + { 33986, 37, /* 0.15 */ }, + { 35586, 36, /* 0.14 */ }, + { 37253, 36, /* 0.14 */ }, + { 38992, 35, /* 0.14 */ }, + { 40808, 35, /* 0.14 */ }, + { 42707, 34, /* 0.13 */ }, + { 44694, 33, /* 0.13 */ }, + { 46776, 33, /* 0.13 */ }, + { 48961, 32, /* 0.13 */ }, + { 51258, 32, /* 0.13 */ }, + { 53677, 31, /* 0.12 */ }, + { 56230, 30, /* 0.12 */ }, + { 58932, 30, /* 0.12 */ }, + { 61799, 29, /* 0.12 */ }, + { 64851, 28, /* 0.11 */ }, + { 68113, 28, /* 0.11 */ }, + { 71617, 27, /* 0.11 */ }, + { 75401, 26, /* 0.10 */ }, + { 79517, 26, /* 0.10 */ }, + { 84035, 25, /* 0.10 */ }, + { 89053, 24, /* 0.10 */ }, +}; + +#define HSTCP_AIMD_MAX ARRAY_SIZE(hstcp_aimd_vals) + +struct hstcp { + u32 ai; +}; + +static void hstcp_init(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct hstcp *ca = inet_csk_ca(sk); + + ca->ai = 0; + + /* Ensure the MD arithmetic works. This is somewhat pedantic, + * since I don't think we will see a cwnd this large. :) */ + tp->snd_cwnd_clamp = min_t(u32, tp->snd_cwnd_clamp, 0xffffffff/128); +} + +static void hstcp_cong_avoid(struct sock *sk, u32 ack, u32 acked) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct hstcp *ca = inet_csk_ca(sk); + + if (!tcp_is_cwnd_limited(sk)) + return; + + if (tcp_in_slow_start(tp)) + tcp_slow_start(tp, acked); + else { + /* Update AIMD parameters. + * + * We want to guarantee that: + * hstcp_aimd_vals[ca->ai-1].cwnd < + * snd_cwnd <= + * hstcp_aimd_vals[ca->ai].cwnd + */ + if (tcp_snd_cwnd(tp) > hstcp_aimd_vals[ca->ai].cwnd) { + while (tcp_snd_cwnd(tp) > hstcp_aimd_vals[ca->ai].cwnd && + ca->ai < HSTCP_AIMD_MAX - 1) + ca->ai++; + } else if (ca->ai && tcp_snd_cwnd(tp) <= hstcp_aimd_vals[ca->ai-1].cwnd) { + while (ca->ai && tcp_snd_cwnd(tp) <= hstcp_aimd_vals[ca->ai-1].cwnd) + ca->ai--; + } + + /* Do additive increase */ + if (tcp_snd_cwnd(tp) < tp->snd_cwnd_clamp) { + /* cwnd = cwnd + a(w) / cwnd */ + tp->snd_cwnd_cnt += ca->ai + 1; + if (tp->snd_cwnd_cnt >= tcp_snd_cwnd(tp)) { + tp->snd_cwnd_cnt -= tcp_snd_cwnd(tp); + tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) + 1); + } + } + } +} + +static u32 hstcp_ssthresh(struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + struct hstcp *ca = inet_csk_ca(sk); + + /* Do multiplicative decrease */ + return max(tcp_snd_cwnd(tp) - ((tcp_snd_cwnd(tp) * hstcp_aimd_vals[ca->ai].md) >> 8), 2U); +} + +static struct tcp_congestion_ops tcp_highspeed __read_mostly = { + .init = hstcp_init, + .ssthresh = hstcp_ssthresh, + .undo_cwnd = tcp_reno_undo_cwnd, + .cong_avoid = hstcp_cong_avoid, + + .owner = THIS_MODULE, + .name = "highspeed" +}; + +static int __init hstcp_register(void) +{ + BUILD_BUG_ON(sizeof(struct hstcp) > ICSK_CA_PRIV_SIZE); + return tcp_register_congestion_control(&tcp_highspeed); +} + +static void __exit hstcp_unregister(void) +{ + tcp_unregister_congestion_control(&tcp_highspeed); +} + +module_init(hstcp_register); +module_exit(hstcp_unregister); + +MODULE_AUTHOR("John Heffner"); +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("High Speed TCP"); |