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https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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f4805eded7
TCP peformance with TSO over networks with delay is awful. On a 100Mbit link with 150ms delay, we get 4Mbits/sec with TSO and 50Mbits/sec without TSO. The problem is with TSO, we intentionally do not keep the maximum number of packets in flight to fill the window, we hold out to until we can send a MSS chunk. But, we also don't update the congestion window unless we have filled, as per RFC2861. This patch replaces the check for the congestion window being full with something smarter that accounts for TSO. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
185 lines
4.8 KiB
C
185 lines
4.8 KiB
C
/*
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* Sally Floyd's High Speed TCP (RFC 3649) congestion control
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*
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* See http://www.icir.org/floyd/hstcp.html
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*
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* John Heffner <jheffner@psc.edu>
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*/
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#include <linux/config.h>
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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 adk, u32 rtt,
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u32 in_flight, u32 pkts_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, in_flight))
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return;
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if (tp->snd_cwnd <= tp->snd_ssthresh) {
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if (tp->snd_cwnd < tp->snd_cwnd_clamp)
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tp->snd_cwnd++;
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} else {
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/* Update AIMD parameters */
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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)
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ca->ai++;
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} else 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 > 0)
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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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tp->snd_cwnd_cnt += ca->ai;
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if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
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tp->snd_cwnd++;
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tp->snd_cwnd_cnt -= 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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const 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 = {
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.init = hstcp_init,
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.ssthresh = hstcp_ssthresh,
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.cong_avoid = hstcp_cong_avoid,
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.min_cwnd = tcp_reno_min_cwnd,
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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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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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