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