310 lines
7.6 KiB
C
310 lines
7.6 KiB
C
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/*
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* MPTCP implementation - OPPORTUNISTIC LINKED INCREASES CONGESTION CONTROL:
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*
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* Algorithm design:
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* Ramin Khalili <ramin.khalili@epfl.ch>
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* Nicolas Gast <nicolas.gast@epfl.ch>
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* Jean-Yves Le Boudec <jean-yves.leboudec@epfl.ch>
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*
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* Implementation:
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* Ramin Khalili <ramin.khalili@epfl.ch>
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*
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* Ported to the official MPTCP-kernel:
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* Christoph Paasch <christoph.paasch@uclouvain.be>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <net/tcp.h>
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#include <net/mptcp.h>
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#include <linux/module.h>
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static int scale = 10;
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struct mptcp_olia {
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u32 mptcp_loss1;
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u32 mptcp_loss2;
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u32 mptcp_loss3;
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int epsilon_num;
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u32 epsilon_den;
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int mptcp_snd_cwnd_cnt;
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};
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static inline int mptcp_olia_sk_can_send(const struct sock *sk)
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{
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return mptcp_sk_can_send(sk) && tcp_sk(sk)->srtt_us;
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}
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static inline u64 mptcp_olia_scale(u64 val, int scale)
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{
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return (u64) val << scale;
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}
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/* take care of artificially inflate (see RFC5681)
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* of cwnd during fast-retransmit phase
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*/
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static u32 mptcp_get_crt_cwnd(struct sock *sk)
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{
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const struct inet_connection_sock *icsk = inet_csk(sk);
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if (icsk->icsk_ca_state == TCP_CA_Recovery)
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return tcp_sk(sk)->snd_ssthresh;
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else
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return tcp_sk(sk)->snd_cwnd;
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}
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/* return the dominator of the first term of the increasing term */
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static u64 mptcp_get_rate(const struct mptcp_cb *mpcb , u32 path_rtt)
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{
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struct sock *sk;
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u64 rate = 1; /* We have to avoid a zero-rate because it is used as a divisor */
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mptcp_for_each_sk(mpcb, sk) {
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struct tcp_sock *tp = tcp_sk(sk);
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u64 scaled_num;
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u32 tmp_cwnd;
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if (!mptcp_olia_sk_can_send(sk))
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continue;
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tmp_cwnd = mptcp_get_crt_cwnd(sk);
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scaled_num = mptcp_olia_scale(tmp_cwnd, scale) * path_rtt;
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rate += div_u64(scaled_num , tp->srtt_us);
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}
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rate *= rate;
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return rate;
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}
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/* find the maximum cwnd, used to find set M */
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static u32 mptcp_get_max_cwnd(const struct mptcp_cb *mpcb)
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{
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struct sock *sk;
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u32 best_cwnd = 0;
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mptcp_for_each_sk(mpcb, sk) {
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u32 tmp_cwnd;
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if (!mptcp_olia_sk_can_send(sk))
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continue;
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tmp_cwnd = mptcp_get_crt_cwnd(sk);
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if (tmp_cwnd > best_cwnd)
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best_cwnd = tmp_cwnd;
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}
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return best_cwnd;
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}
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static void mptcp_get_epsilon(const struct mptcp_cb *mpcb)
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{
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struct mptcp_olia *ca;
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struct tcp_sock *tp;
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struct sock *sk;
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u64 tmp_int, tmp_rtt, best_int = 0, best_rtt = 1;
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u32 max_cwnd, tmp_cwnd;
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u8 M = 0, B_not_M = 0;
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/* TODO - integrate this in the following loop - we just want to iterate once */
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max_cwnd = mptcp_get_max_cwnd(mpcb);
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/* find the best path */
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mptcp_for_each_sk(mpcb, sk) {
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tp = tcp_sk(sk);
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ca = inet_csk_ca(sk);
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if (!mptcp_olia_sk_can_send(sk))
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continue;
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tmp_rtt = (u64)tp->srtt_us * tp->srtt_us;
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/* TODO - check here and rename variables */
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tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
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ca->mptcp_loss2 - ca->mptcp_loss1);
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if ((u64)tmp_int * best_rtt >= (u64)best_int * tmp_rtt) {
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best_rtt = tmp_rtt;
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best_int = tmp_int;
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}
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}
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/* TODO - integrate this here in mptcp_get_max_cwnd and in the previous loop */
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/* find the size of M and B_not_M */
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mptcp_for_each_sk(mpcb, sk) {
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tp = tcp_sk(sk);
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ca = inet_csk_ca(sk);
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if (!mptcp_olia_sk_can_send(sk))
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continue;
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tmp_cwnd = mptcp_get_crt_cwnd(sk);
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if (tmp_cwnd == max_cwnd) {
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M++;
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} else {
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tmp_rtt = (u64)tp->srtt_us * tp->srtt_us;
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tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
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ca->mptcp_loss2 - ca->mptcp_loss1);
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if ((u64)tmp_int * best_rtt == (u64)best_int * tmp_rtt)
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B_not_M++;
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}
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}
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/* check if the path is in M or B_not_M and set the value of epsilon accordingly */
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mptcp_for_each_sk(mpcb, sk) {
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tp = tcp_sk(sk);
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ca = inet_csk_ca(sk);
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if (!mptcp_olia_sk_can_send(sk))
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continue;
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if (B_not_M == 0) {
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ca->epsilon_num = 0;
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ca->epsilon_den = 1;
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} else {
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tmp_rtt = (u64)tp->srtt_us * tp->srtt_us;
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tmp_int = max(ca->mptcp_loss3 - ca->mptcp_loss2,
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ca->mptcp_loss2 - ca->mptcp_loss1);
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tmp_cwnd = mptcp_get_crt_cwnd(sk);
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if (tmp_cwnd < max_cwnd &&
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(u64)tmp_int * best_rtt == (u64)best_int * tmp_rtt) {
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ca->epsilon_num = 1;
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ca->epsilon_den = mpcb->cnt_established * B_not_M;
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} else if (tmp_cwnd == max_cwnd) {
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ca->epsilon_num = -1;
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ca->epsilon_den = mpcb->cnt_established * M;
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} else {
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ca->epsilon_num = 0;
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ca->epsilon_den = 1;
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}
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}
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}
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}
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/* setting the initial values */
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static void mptcp_olia_init(struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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struct mptcp_olia *ca = inet_csk_ca(sk);
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if (mptcp(tp)) {
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ca->mptcp_loss1 = tp->snd_una;
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ca->mptcp_loss2 = tp->snd_una;
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ca->mptcp_loss3 = tp->snd_una;
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ca->mptcp_snd_cwnd_cnt = 0;
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ca->epsilon_num = 0;
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ca->epsilon_den = 1;
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}
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}
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/* updating inter-loss distance and ssthresh */
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static void mptcp_olia_set_state(struct sock *sk, u8 new_state)
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{
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if (!mptcp(tcp_sk(sk)))
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return;
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if (new_state == TCP_CA_Loss ||
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new_state == TCP_CA_Recovery || new_state == TCP_CA_CWR) {
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struct mptcp_olia *ca = inet_csk_ca(sk);
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if (ca->mptcp_loss3 != ca->mptcp_loss2 &&
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!inet_csk(sk)->icsk_retransmits) {
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ca->mptcp_loss1 = ca->mptcp_loss2;
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ca->mptcp_loss2 = ca->mptcp_loss3;
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}
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}
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}
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/* main algorithm */
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static void mptcp_olia_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 mptcp_olia *ca = inet_csk_ca(sk);
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const struct mptcp_cb *mpcb = tp->mpcb;
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u64 inc_num, inc_den, rate, cwnd_scaled;
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if (!mptcp(tp)) {
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tcp_reno_cong_avoid(sk, ack, acked);
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return;
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}
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ca->mptcp_loss3 = tp->snd_una;
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if (!tcp_is_cwnd_limited(sk))
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return;
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/* slow start if it is in the safe area */
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if (tcp_in_slow_start(tp)) {
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tcp_slow_start(tp, acked);
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return;
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}
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mptcp_get_epsilon(mpcb);
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rate = mptcp_get_rate(mpcb, tp->srtt_us);
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cwnd_scaled = mptcp_olia_scale(tp->snd_cwnd, scale);
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inc_den = ca->epsilon_den * tp->snd_cwnd * rate ? : 1;
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/* calculate the increasing term, scaling is used to reduce the rounding effect */
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if (ca->epsilon_num == -1) {
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if (ca->epsilon_den * cwnd_scaled * cwnd_scaled < rate) {
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inc_num = rate - ca->epsilon_den *
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cwnd_scaled * cwnd_scaled;
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ca->mptcp_snd_cwnd_cnt -= div64_u64(
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mptcp_olia_scale(inc_num , scale) , inc_den);
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} else {
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inc_num = ca->epsilon_den *
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cwnd_scaled * cwnd_scaled - rate;
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ca->mptcp_snd_cwnd_cnt += div64_u64(
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mptcp_olia_scale(inc_num , scale) , inc_den);
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}
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} else {
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inc_num = ca->epsilon_num * rate +
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ca->epsilon_den * cwnd_scaled * cwnd_scaled;
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ca->mptcp_snd_cwnd_cnt += div64_u64(
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mptcp_olia_scale(inc_num , scale) , inc_den);
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}
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if (ca->mptcp_snd_cwnd_cnt >= (1 << scale) - 1) {
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if (tp->snd_cwnd < tp->snd_cwnd_clamp)
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tp->snd_cwnd++;
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ca->mptcp_snd_cwnd_cnt = 0;
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} else if (ca->mptcp_snd_cwnd_cnt <= 0 - (1 << scale) + 1) {
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tp->snd_cwnd = max((int) 1 , (int) tp->snd_cwnd - 1);
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ca->mptcp_snd_cwnd_cnt = 0;
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}
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}
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static struct tcp_congestion_ops mptcp_olia = {
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.init = mptcp_olia_init,
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.ssthresh = tcp_reno_ssthresh,
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.cong_avoid = mptcp_olia_cong_avoid,
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.set_state = mptcp_olia_set_state,
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.owner = THIS_MODULE,
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.name = "olia",
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};
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static int __init mptcp_olia_register(void)
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{
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BUILD_BUG_ON(sizeof(struct mptcp_olia) > ICSK_CA_PRIV_SIZE);
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return tcp_register_congestion_control(&mptcp_olia);
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}
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static void __exit mptcp_olia_unregister(void)
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{
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tcp_unregister_congestion_control(&mptcp_olia);
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}
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module_init(mptcp_olia_register);
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module_exit(mptcp_olia_unregister);
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MODULE_AUTHOR("Ramin Khalili, Nicolas Gast, Jean-Yves Le Boudec");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("MPTCP COUPLED CONGESTION CONTROL");
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MODULE_VERSION("0.1");
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