--- /dev/null
+/*
+ * Sally Floyd's High Speed TCP (RFC 3649) congestion control
+ *
+ * See http://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 (tp->snd_cwnd <= tp->snd_ssthresh)
+ 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 (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) {
+ while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd &&
+ ca->ai < HSTCP_AIMD_MAX - 1)
+ ca->ai++;
+ } else if (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd) {
+ while (ca->ai && tp->snd_cwnd <= hstcp_aimd_vals[ca->ai-1].cwnd)
+ ca->ai--;
+ }
+
+ /* Do additive increase */
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp) {
+ /* cwnd = cwnd + a(w) / cwnd */
+ tp->snd_cwnd_cnt += ca->ai + 1;
+ if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ tp->snd_cwnd_cnt -= tp->snd_cwnd;
+ tp->snd_cwnd++;
+ }
+ }
+ }
+}
+
+static u32 hstcp_ssthresh(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ const struct hstcp *ca = inet_csk_ca(sk);
+
+ /* Do multiplicative decrease */
+ return max(tp->snd_cwnd - ((tp->snd_cwnd * hstcp_aimd_vals[ca->ai].md) >> 8), 2U);
+}
+
+
+static struct tcp_congestion_ops tcp_highspeed __read_mostly = {
+ .init = hstcp_init,
+ .ssthresh = hstcp_ssthresh,
+ .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");
Code Review / kvmfornfv.git / blobdiff