--- /dev/null
+/*
+ *
+ * YeAH TCP
+ *
+ * For further details look at:
+ * http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
+ *
+ */
+
+#include "tcp_yeah.h"
+
+/* Default values of the Vegas variables, in fixed-point representation
+ * with V_PARAM_SHIFT bits to the right of the binary point.
+ */
+#define V_PARAM_SHIFT 1
+
+#define TCP_YEAH_ALPHA 80 //lin number of packets queued at the bottleneck
+#define TCP_YEAH_GAMMA 1 //lin fraction of queue to be removed per rtt
+#define TCP_YEAH_DELTA 3 //log minimum fraction of cwnd to be removed on loss
+#define TCP_YEAH_EPSILON 1 //log maximum fraction to be removed on early decongestion
+#define TCP_YEAH_PHY 8 //lin maximum delta from base
+#define TCP_YEAH_RHO 16 //lin minumum number of consecutive rtt to consider competition on loss
+#define TCP_YEAH_ZETA 50 //lin minimum number of state switchs to reset reno_count
+
+#define TCP_SCALABLE_AI_CNT 100U
+
+/* YeAH variables */
+struct yeah {
+ /* Vegas */
+ u32 beg_snd_nxt; /* right edge during last RTT */
+ u32 beg_snd_una; /* left edge during last RTT */
+ u32 beg_snd_cwnd; /* saves the size of the cwnd */
+ u8 doing_vegas_now;/* if true, do vegas for this RTT */
+ u16 cntRTT; /* # of RTTs measured within last RTT */
+ u32 minRTT; /* min of RTTs measured within last RTT (in usec) */
+ u32 baseRTT; /* the min of all Vegas RTT measurements seen (in usec) */
+
+ /* YeAH */
+ u32 lastQ;
+ u32 doing_reno_now;
+
+ u32 reno_count;
+ u32 fast_count;
+
+ u32 pkts_acked;
+};
+
+static void tcp_yeah_init(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct yeah *yeah = inet_csk_ca(sk);
+
+ tcp_vegas_init(sk);
+
+ yeah->doing_reno_now = 0;
+ yeah->lastQ = 0;
+
+ yeah->reno_count = 2;
+
+ /* 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 tcp_yeah_pkts_acked(struct sock *sk, u32 pkts_acked)
+{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+ struct yeah *yeah = inet_csk_ca(sk);
+
+ if (icsk->icsk_ca_state == TCP_CA_Open)
+ yeah->pkts_acked = pkts_acked;
+}
+
+/* 64bit divisor, dividend and result. dynamic precision */
+static inline u64 div64_64(u64 dividend, u64 divisor)
+{
+ u32 d = divisor;
+
+ if (divisor > 0xffffffffULL) {
+ unsigned int shift = fls(divisor >> 32);
+
+ d = divisor >> shift;
+ dividend >>= shift;
+ }
+
+ /* avoid 64 bit division if possible */
+ if (dividend >> 32)
+ do_div(dividend, d);
+ else
+ dividend = (u32) dividend / d;
+
+ return dividend;
+}
+
+static void tcp_yeah_cong_avoid(struct sock *sk, u32 ack,
+ u32 seq_rtt, u32 in_flight, int flag)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct yeah *yeah = inet_csk_ca(sk);
+
+ if (!tcp_is_cwnd_limited(sk, in_flight))
+ return;
+
+ if (tp->snd_cwnd <= tp->snd_ssthresh) {
+ tcp_slow_start(tp);
+ } else if (!yeah->doing_reno_now) {
+ /* Scalable */
+
+ tp->snd_cwnd_cnt+=yeah->pkts_acked;
+ if (tp->snd_cwnd_cnt > min(tp->snd_cwnd, TCP_SCALABLE_AI_CNT)){
+ if (tp->snd_cwnd < tp->snd_cwnd_clamp)
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ }
+
+ yeah->pkts_acked = 1;
+
+ } else {
+ /* Reno */
+
+ if (tp->snd_cwnd_cnt < tp->snd_cwnd)
+ tp->snd_cwnd_cnt++;
+
+ if (tp->snd_cwnd_cnt >= tp->snd_cwnd) {
+ tp->snd_cwnd++;
+ tp->snd_cwnd_cnt = 0;
+ }
+ }
+
+ /* The key players are v_beg_snd_una and v_beg_snd_nxt.
+ *
+ * These are so named because they represent the approximate values
+ * of snd_una and snd_nxt at the beginning of the current RTT. More
+ * precisely, they represent the amount of data sent during the RTT.
+ * At the end of the RTT, when we receive an ACK for v_beg_snd_nxt,
+ * we will calculate that (v_beg_snd_nxt - v_beg_snd_una) outstanding
+ * bytes of data have been ACKed during the course of the RTT, giving
+ * an "actual" rate of:
+ *
+ * (v_beg_snd_nxt - v_beg_snd_una) / (rtt duration)
+ *
+ * Unfortunately, v_beg_snd_una is not exactly equal to snd_una,
+ * because delayed ACKs can cover more than one segment, so they
+ * don't line up yeahly with the boundaries of RTTs.
+ *
+ * Another unfortunate fact of life is that delayed ACKs delay the
+ * advance of the left edge of our send window, so that the number
+ * of bytes we send in an RTT is often less than our cwnd will allow.
+ * So we keep track of our cwnd separately, in v_beg_snd_cwnd.
+ */
+
+ if (after(ack, yeah->beg_snd_nxt)) {
+
+ /* We do the Vegas calculations only if we got enough RTT
+ * samples that we can be reasonably sure that we got
+ * at least one RTT sample that wasn't from a delayed ACK.
+ * If we only had 2 samples total,
+ * then that means we're getting only 1 ACK per RTT, which
+ * means they're almost certainly delayed ACKs.
+ * If we have 3 samples, we should be OK.
+ */
+
+ if (yeah->cntRTT > 2) {
+ u32 rtt;
+ u32 queue, maxqueue;
+
+ /* We have enough RTT samples, so, using the Vegas
+ * algorithm, we determine if we should increase or
+ * decrease cwnd, and by how much.
+ */
+
+ /* Pluck out the RTT we are using for the Vegas
+ * calculations. This is the min RTT seen during the
+ * last RTT. Taking the min filters out the effects
+ * of delayed ACKs, at the cost of noticing congestion
+ * a bit later.
+ */
+ rtt = yeah->minRTT;
+
+ queue = (u32)div64_64((u64)tp->snd_cwnd * (rtt - yeah->baseRTT), rtt);
+
+ maxqueue = TCP_YEAH_ALPHA;
+
+ if (queue > maxqueue ||
+ rtt - yeah->baseRTT > (yeah->baseRTT / TCP_YEAH_PHY)) {
+
+ if (queue > maxqueue && tp->snd_cwnd > yeah->reno_count) {
+ u32 reduction = min( queue / TCP_YEAH_GAMMA ,
+ tp->snd_cwnd >> TCP_YEAH_EPSILON );
+
+ tp->snd_cwnd -= reduction;
+
+ tp->snd_cwnd = max( tp->snd_cwnd, yeah->reno_count);
+
+ tp->snd_ssthresh = tp->snd_cwnd;
+ }
+
+ if (yeah->reno_count <= 2)
+ yeah->reno_count = max( tp->snd_cwnd>>1, 2U);
+ else
+ yeah->reno_count++;
+
+ yeah->doing_reno_now =
+ min_t( u32, yeah->doing_reno_now + 1 , 0xffffff);
+
+ } else {
+ yeah->fast_count++;
+
+ if (yeah->fast_count > TCP_YEAH_ZETA) {
+ yeah->reno_count = 2;
+ yeah->fast_count = 0;
+ }
+
+ yeah->doing_reno_now = 0;
+ }
+
+ yeah->lastQ = queue;
+
+ }
+
+ /* Save the extent of the current window so we can use this
+ * at the end of the next RTT.
+ */
+ yeah->beg_snd_una = yeah->beg_snd_nxt;
+ yeah->beg_snd_nxt = tp->snd_nxt;
+ yeah->beg_snd_cwnd = tp->snd_cwnd;
+
+ /* Wipe the slate clean for the next RTT. */
+ yeah->cntRTT = 0;
+ yeah->minRTT = 0x7fffffff;
+ }
+}
+
+static u32 tcp_yeah_ssthresh(struct sock *sk) {
+ const struct tcp_sock *tp = tcp_sk(sk);
+ struct yeah *yeah = inet_csk_ca(sk);
+ u32 reduction;
+
+ if (yeah->doing_reno_now < TCP_YEAH_RHO) {
+ reduction = yeah->lastQ;
+
+ reduction = min( reduction, max(tp->snd_cwnd>>1, 2U) );
+
+ reduction = max( reduction, tp->snd_cwnd >> TCP_YEAH_DELTA);
+ } else
+ reduction = max(tp->snd_cwnd>>1,2U);
+
+ yeah->fast_count = 0;
+ yeah->reno_count = max(yeah->reno_count>>1, 2U);
+
+ return tp->snd_cwnd - reduction;
+}
+
+static struct tcp_congestion_ops tcp_yeah = {
+ .init = tcp_yeah_init,
+ .ssthresh = tcp_yeah_ssthresh,
+ .cong_avoid = tcp_yeah_cong_avoid,
+ .min_cwnd = tcp_reno_min_cwnd,
+ .rtt_sample = tcp_vegas_rtt_calc,
+ .set_state = tcp_vegas_state,
+ .cwnd_event = tcp_vegas_cwnd_event,
+ .get_info = tcp_vegas_get_info,
+ .pkts_acked = tcp_yeah_pkts_acked,
+
+ .owner = THIS_MODULE,
+ .name = "yeah",
+};
+
+static int __init tcp_yeah_register(void)
+{
+ BUG_ON(sizeof(struct yeah) > ICSK_CA_PRIV_SIZE);
+ tcp_register_congestion_control(&tcp_yeah);
+ return 0;
+}
+
+static void __exit tcp_yeah_unregister(void)
+{
+ tcp_unregister_congestion_control(&tcp_yeah);
+}
+
+module_init(tcp_yeah_register);
+module_exit(tcp_yeah_unregister);
+
+MODULE_AUTHOR("Angelo P. Castellani");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("YeAH TCP");
--- /dev/null
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/inet_diag.h>
+
+#include <net/tcp.h>
+
+/* Vegas variables */
+struct vegas {
+ u32 beg_snd_nxt; /* right edge during last RTT */
+ u32 beg_snd_una; /* left edge during last RTT */
+ u32 beg_snd_cwnd; /* saves the size of the cwnd */
+ u8 doing_vegas_now;/* if true, do vegas for this RTT */
+ u16 cntRTT; /* # of RTTs measured within last RTT */
+ u32 minRTT; /* min of RTTs measured within last RTT (in usec) */
+ u32 baseRTT; /* the min of all Vegas RTT measurements seen (in usec) */
+};
+
+/* There are several situations when we must "re-start" Vegas:
+ *
+ * o when a connection is established
+ * o after an RTO
+ * o after fast recovery
+ * o when we send a packet and there is no outstanding
+ * unacknowledged data (restarting an idle connection)
+ *
+ * In these circumstances we cannot do a Vegas calculation at the
+ * end of the first RTT, because any calculation we do is using
+ * stale info -- both the saved cwnd and congestion feedback are
+ * stale.
+ *
+ * Instead we must wait until the completion of an RTT during
+ * which we actually receive ACKs.
+ */
+static inline void vegas_enable(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ /* Begin taking Vegas samples next time we send something. */
+ vegas->doing_vegas_now = 1;
+
+ /* Set the beginning of the next send window. */
+ vegas->beg_snd_nxt = tp->snd_nxt;
+
+ vegas->cntRTT = 0;
+ vegas->minRTT = 0x7fffffff;
+}
+
+/* Stop taking Vegas samples for now. */
+static inline void vegas_disable(struct sock *sk)
+{
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ vegas->doing_vegas_now = 0;
+}
+
+static void tcp_vegas_init(struct sock *sk)
+{
+ struct vegas *vegas = inet_csk_ca(sk);
+
+ vegas->baseRTT = 0x7fffffff;
+ vegas_enable(sk);
+}
+
+static void tcp_vegas_state(struct sock *sk, u8 ca_state)
+{
+
+ if (ca_state == TCP_CA_Open)
+ vegas_enable(sk);
+ else
+ vegas_disable(sk);
+}
+
+/* Do RTT sampling needed for Vegas.
+ * Basically we:
+ * o min-filter RTT samples from within an RTT to get the current
+ * propagation delay + queuing delay (we are min-filtering to try to
+ * avoid the effects of delayed ACKs)
+ * o min-filter RTT samples from a much longer window (forever for now)
+ * to find the propagation delay (baseRTT)
+ */
+static void tcp_vegas_rtt_calc(struct sock *sk, u32 usrtt)
+{
+ struct vegas *vegas = inet_csk_ca(sk);
+ u32 vrtt = usrtt + 1; /* Never allow zero rtt or baseRTT */
+
+ /* Filter to find propagation delay: */
+ if (vrtt < vegas->baseRTT)
+ vegas->baseRTT = vrtt;
+
+ /* Find the min RTT during the last RTT to find
+ * the current prop. delay + queuing delay:
+ */
+ vegas->minRTT = min(vegas->minRTT, vrtt);
+ vegas->cntRTT++;
+}
+
+/*
+ * If the connection is idle and we are restarting,
+ * then we don't want to do any Vegas calculations
+ * until we get fresh RTT samples. So when we
+ * restart, we reset our Vegas state to a clean
+ * slate. After we get acks for this flight of
+ * packets, _then_ we can make Vegas calculations
+ * again.
+ */
+static void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event)
+{
+ if (event == CA_EVENT_CWND_RESTART ||
+ event == CA_EVENT_TX_START)
+ tcp_vegas_init(sk);
+}
+
+/* Extract info for Tcp socket info provided via netlink. */
+static void tcp_vegas_get_info(struct sock *sk, u32 ext,
+ struct sk_buff *skb)
+{
+ const struct vegas *ca = inet_csk_ca(sk);
+ if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
+ struct tcpvegas_info *info;
+
+ info = RTA_DATA(__RTA_PUT(skb, INET_DIAG_VEGASINFO,
+ sizeof(*info)));
+
+ info->tcpv_enabled = ca->doing_vegas_now;
+ info->tcpv_rttcnt = ca->cntRTT;
+ info->tcpv_rtt = ca->baseRTT;
+ info->tcpv_minrtt = ca->minRTT;
+ rtattr_failure: ;
+ }
+}
+
+
projects / linux-2.6 / commitdiff