Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 239 insertions, 0 deletions

diff --git a/net/ipv4/tcp_yeah.c b/net/ipv4/tcp_yeah.c
new file mode 100644
index 0000000000..18b07ff5d2
--- /dev/null
+++ b/net/ipv4/tcp_yeah.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ *   YeAH TCP
+ *
+ * For further details look at:
+ *   https://web.archive.org/web/20080316215752/http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf
+ *
+ */
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/inet_diag.h>
+
+#include <net/tcp.h>
+
+#include "tcp_vegas.h"
+
+#define TCP_YEAH_ALPHA       80 /* number of packets queued at the bottleneck */
+#define TCP_YEAH_GAMMA        1 /* 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 /* maximum delta from base */
+#define TCP_YEAH_RHO         16 /* minimum number of consecutive rtt to consider competition on loss */
+#define TCP_YEAH_ZETA        50 /* minimum number of state switches to reset reno_count */
+
+#define TCP_SCALABLE_AI_CNT	 100U
+
+/* YeAH variables */
+struct yeah {
+	struct vegas vegas;	/* must be first */
+
+	/* YeAH */
+	u32 lastQ;
+	u32 doing_reno_now;
+
+	u32 reno_count;
+	u32 fast_count;
+};
+
+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_cong_avoid(struct sock *sk, u32 ack, u32 acked)
+{
+	struct tcp_sock *tp = tcp_sk(sk);
+	struct yeah *yeah = inet_csk_ca(sk);
+
+	if (!tcp_is_cwnd_limited(sk))
+		return;
+
+	if (tcp_in_slow_start(tp)) {
+		acked = tcp_slow_start(tp, acked);
+		if (!acked)
+			goto do_vegas;
+	}
+
+	if (!yeah->doing_reno_now) {
+		/* Scalable */
+		tcp_cong_avoid_ai(tp, min(tcp_snd_cwnd(tp), TCP_SCALABLE_AI_CNT),
+				  acked);
+	} else {
+		/* Reno */
+		tcp_cong_avoid_ai(tp, tcp_snd_cwnd(tp), acked);
+	}
+
+	/* The key players are v_vegas.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_vegas.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_vegas.beg_snd_una) / (rtt duration)
+	 *
+	 * Unfortunately, v_vegas.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.
+	 */
+do_vegas:
+	if (after(ack, yeah->vegas.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->vegas.cntRTT > 2) {
+			u32 rtt, queue;
+			u64 bw;
+
+			/* 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->vegas.minRTT;
+
+			/* Compute excess number of packets above bandwidth
+			 * Avoid doing full 64 bit divide.
+			 */
+			bw = tcp_snd_cwnd(tp);
+			bw *= rtt - yeah->vegas.baseRTT;
+			do_div(bw, rtt);
+			queue = bw;
+
+			if (queue > TCP_YEAH_ALPHA ||
+			    rtt - yeah->vegas.baseRTT > (yeah->vegas.baseRTT / TCP_YEAH_PHY)) {
+				if (queue > TCP_YEAH_ALPHA &&
+				    tcp_snd_cwnd(tp) > yeah->reno_count) {
+					u32 reduction = min(queue / TCP_YEAH_GAMMA ,
+							    tcp_snd_cwnd(tp) >> TCP_YEAH_EPSILON);
+
+					tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) - reduction);
+
+					tcp_snd_cwnd_set(tp, max(tcp_snd_cwnd(tp),
+								 yeah->reno_count));
+
+					tp->snd_ssthresh = tcp_snd_cwnd(tp);
+				}
+
+				if (yeah->reno_count <= 2)
+					yeah->reno_count = max(tcp_snd_cwnd(tp)>>1, 2U);
+				else
+					yeah->reno_count++;
+
+				yeah->doing_reno_now = min(yeah->doing_reno_now + 1,
+							   0xffffffU);
+			} 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->vegas.beg_snd_una  = yeah->vegas.beg_snd_nxt;
+		yeah->vegas.beg_snd_nxt  = tp->snd_nxt;
+		yeah->vegas.beg_snd_cwnd = tcp_snd_cwnd(tp);
+
+		/* Wipe the slate clean for the next RTT. */
+		yeah->vegas.cntRTT = 0;
+		yeah->vegas.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(tcp_snd_cwnd(tp)>>1, 2U));
+
+		reduction = max(reduction, tcp_snd_cwnd(tp) >> TCP_YEAH_DELTA);
+	} else
+		reduction = max(tcp_snd_cwnd(tp)>>1, 2U);
+
+	yeah->fast_count = 0;
+	yeah->reno_count = max(yeah->reno_count>>1, 2U);
+
+	return max_t(int, tcp_snd_cwnd(tp) - reduction, 2);
+}
+
+static struct tcp_congestion_ops tcp_yeah __read_mostly = {
+	.init		= tcp_yeah_init,
+	.ssthresh	= tcp_yeah_ssthresh,
+	.undo_cwnd      = tcp_reno_undo_cwnd,
+	.cong_avoid	= tcp_yeah_cong_avoid,
+	.set_state	= tcp_vegas_state,
+	.cwnd_event	= tcp_vegas_cwnd_event,
+	.get_info	= tcp_vegas_get_info,
+	.pkts_acked	= tcp_vegas_pkts_acked,
+
+	.owner		= THIS_MODULE,
+	.name		= "yeah",
+};
+
+static int __init tcp_yeah_register(void)
+{
+	BUILD_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");