Adding upstream version 2.6.12.upstream/2.6.12upstream

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

1 files changed, 283 insertions, 0 deletions

diff --git a/src/quic_cc_cubic.c b/src/quic_cc_cubic.c
new file mode 100644
index 0000000..dc6ef9f
--- /dev/null
+++ b/src/quic_cc_cubic.c
@@ -0,0 +1,283 @@
+#include <haproxy/trace.h>
+#include <haproxy/quic_cc.h>
+
+/* This source file is highly inspired from Linux kernel source file
+ * implementation for TCP Cubic. In fact, we have no choice if we do
+ * not want to use any floating point operations to be fast!
+ * (See net/ipv4/tcp_cubic.c)
+ */
+#define TRACE_SOURCE    &trace_quic
+
+#define CUBIC_BETA_SCALE       1024
+#define CUBIC_BETA_SCALE_SHIFT   10
+/* beta = 0.7 ; C = 0.4 */
+#define CUBIC_BETA   717 /*    CUBIC_BETA / CUBIC_BETA_SCALE = 0.7 */
+#define CUBIC_C      410 /*       CUBIC_C / CUBIC_BETA_SCALE = 0.4 */
+
+#define CUBIC_BETA_SCALE_FACTOR_SHIFT (3 * CUBIC_BETA_SCALE_SHIFT)
+#define TIME_SCALE_FACTOR_SHIFT  10
+
+/* The maximum value which may be cubed an multiplied by CUBIC_BETA */
+#define CUBIC_DIFF_TIME_LIMIT    355535ULL  /* ms */
+
+/* K cube factor: (1 - beta) / c */
+struct cubic {
+	uint32_t ssthresh;
+	uint32_t remaining_inc;
+	uint32_t remaining_tcp_inc;
+	uint32_t epoch_start;
+	uint32_t origin_point;
+	uint32_t K;
+	uint32_t last_w_max;
+	uint32_t tcp_wnd;
+	uint32_t recovery_start_time;
+};
+
+static void quic_cc_cubic_reset(struct quic_cc *cc)
+{
+	struct cubic *c = quic_cc_priv(cc);
+
+	cc->algo->state = QUIC_CC_ST_SS;
+
+	c->ssthresh = QUIC_CC_INFINITE_SSTHESH;
+	c->remaining_inc = 0;
+	c->remaining_tcp_inc = 0;
+	c->epoch_start = 0;
+	c->origin_point = 0;
+	c->K = 0;
+	c->last_w_max = 0;
+	c->tcp_wnd = 0;
+	c->recovery_start_time = 0;
+}
+
+static int quic_cc_cubic_init(struct quic_cc *cc)
+{
+	quic_cc_cubic_reset(cc);
+	return 1;
+}
+
+/* Cubic root.
+ * Highly inspired from Linux kernel sources.
+ * See net/ipv4/tcp_cubic.c
+ */
+static uint32_t cubic_root(uint64_t val)
+{
+	uint32_t x, b, shift;
+
+	static const uint8_t v[] = {
+		  0,   54,   54,   54,  118,  118,  118,  118,
+		123,  129,  134,  138,  143,  147,  151,  156,
+		157,  161,  164,  168,  170,  173,  176,  179,
+		181,  185,  187,  190,  192,  194,  197,  199,
+		200,  202,  204,  206,  209,  211,  213,  215,
+		217,  219,  221,  222,  224,  225,  227,  229,
+		231,  232,  234,  236,  237,  239,  240,  242,
+		244,  245,  246,  248,  250,  251,  252,  254,
+	};
+
+	if (!val || (b = my_flsl(val)) < 7) {
+		/* val in [0..63] */
+		return ((uint32_t)v[(uint32_t)val] + 35) >> 6;
+	}
+
+	b = ((b * 84) >> 8) - 1;
+	shift = (val >> (b * 3));
+
+	x = ((uint32_t)(((uint32_t)v[shift] + 10) << b)) >> 6;
+
+	x = 2 * x + (uint32_t)(val / ((uint64_t)x * (uint64_t)(x - 1)));
+	x = ((x * 341) >> 10);
+
+	return x;
+}
+
+static inline void quic_cubic_update(struct quic_cc *cc, uint32_t acked)
+{
+	struct cubic *c = quic_cc_priv(cc);
+	struct quic_path *path = container_of(cc, struct quic_path, cc);
+	/* Current cwnd as number of packets */
+	uint32_t t, target, inc, inc_diff;
+	uint64_t delta, diff;
+
+	if (!c->epoch_start) {
+		c->epoch_start = now_ms;
+		if (c->last_w_max <= path->cwnd) {
+			c->K = 0;
+			c->origin_point = path->cwnd;
+		}
+		else {
+			/* K = cubic_root((1 - beta) * W_max / C) */
+			c->K = cubic_root((c->last_w_max - path->cwnd) *
+			                  (CUBIC_BETA_SCALE - CUBIC_BETA) / CUBIC_C / path->mtu) << TIME_SCALE_FACTOR_SHIFT;
+			c->origin_point = c->last_w_max;
+		}
+
+		c->tcp_wnd = path->cwnd;
+		c->remaining_inc = 0;
+		c->remaining_tcp_inc = 0;
+	}
+
+	t = now_ms + path->loss.rtt_min - c->epoch_start;
+	if (t < c->K) {
+		diff = c->K - t;
+	}
+	else {
+		diff = t - c->K;
+	}
+
+	if (diff > CUBIC_DIFF_TIME_LIMIT) {
+		/* TODO : should not happen if we handle the case
+		 * of very late acks receipt. This must be handled as a congestion
+		 * control event: a very late ack should trigger a congestion
+		 * control algorithm reset.
+		 */
+		quic_cc_cubic_reset(cc);
+		return;
+	}
+
+	delta = path->mtu * ((CUBIC_C * diff * diff * diff) >> (10 + 3 * TIME_SCALE_FACTOR_SHIFT));
+	if (t < c->K)
+		target = c->origin_point - delta;
+	else
+		target = c->origin_point + delta;
+
+	if (target > path->cwnd) {
+		inc_diff = c->remaining_inc + path->mtu * (target - path->cwnd);
+		c->remaining_inc = inc_diff % path->cwnd;
+		inc = inc_diff / path->cwnd;
+	}
+	else {
+		/* small increment */
+		inc_diff = c->remaining_inc + path->mtu;
+		c->remaining_inc = inc_diff % (100 * path->cwnd);
+		inc = inc_diff / (100 * path->cwnd);
+	}
+
+	inc_diff = c->remaining_tcp_inc + path->mtu * acked;
+	c->tcp_wnd += inc_diff / path->cwnd;
+	c->remaining_tcp_inc = inc_diff % path->cwnd;
+	/* TCP friendliness */
+	if (c->tcp_wnd > path->cwnd) {
+		uint32_t tcp_inc = path->mtu * (c->tcp_wnd - path->cwnd) / path->cwnd;
+		if (tcp_inc > inc)
+			inc = tcp_inc;
+	}
+
+	path->cwnd += inc;
+}
+
+static void quic_cc_cubic_slow_start(struct quic_cc *cc)
+{
+	quic_cc_cubic_reset(cc);
+}
+
+static void quic_enter_recovery(struct quic_cc *cc)
+{
+	struct quic_path *path = container_of(cc, struct quic_path, cc);
+	struct cubic *c = quic_cc_priv(cc);
+	/* Current cwnd as number of packets */
+
+	c->epoch_start = 0;
+	c->recovery_start_time = now_ms;
+	/* Fast convergence */
+	if (path->cwnd < c->last_w_max) {
+		/* (1 + beta) * path->cwnd / 2 */
+		c->last_w_max = (path->cwnd * (CUBIC_BETA_SCALE + CUBIC_BETA) / 2) >> CUBIC_BETA_SCALE_SHIFT;
+	}
+	else {
+		c->last_w_max = path->cwnd;
+	}
+	path->cwnd = (CUBIC_BETA * path->cwnd) >> CUBIC_BETA_SCALE_SHIFT;
+	c->ssthresh =  QUIC_MAX(path->cwnd, path->min_cwnd);
+}
+
+/* Congestion slow-start callback. */
+static void quic_cc_cubic_ss_cb(struct quic_cc *cc, struct quic_cc_event *ev)
+{
+	struct quic_path *path = container_of(cc, struct quic_path, cc);
+	struct cubic *c = quic_cc_priv(cc);
+
+	TRACE_ENTER(QUIC_EV_CONN_CC, cc->qc, ev);
+	switch (ev->type) {
+	case QUIC_CC_EVT_ACK:
+		/* Do not increase the congestion window in recovery period. */
+		if (ev->ack.time_sent <= c->recovery_start_time)
+			goto out;
+
+		path->cwnd += ev->ack.acked;
+		/* Exit to congestion avoidance if slow start threshold is reached. */
+		if (path->cwnd >= c->ssthresh)
+			cc->algo->state = QUIC_CC_ST_CA;
+		break;
+
+	case QUIC_CC_EVT_LOSS:
+		/* Do not decrease the congestion window when already in recovery period. */
+		if (ev->loss.time_sent <= c->recovery_start_time)
+			goto out;
+
+		quic_enter_recovery(cc);
+		/* Exit to congestion avoidance. */
+		cc->algo->state = QUIC_CC_ST_CA;
+		break;
+
+	case QUIC_CC_EVT_ECN_CE:
+		/* TODO */
+		break;
+	}
+
+ out:
+	TRACE_LEAVE(QUIC_EV_CONN_CC, cc->qc, NULL, cc);
+}
+
+/* Congestion avoidance callback. */
+static void quic_cc_cubic_ca_cb(struct quic_cc *cc, struct quic_cc_event *ev)
+{
+	struct cubic *c = quic_cc_priv(cc);
+
+	TRACE_ENTER(QUIC_EV_CONN_CC, cc->qc, ev);
+	switch (ev->type) {
+	case QUIC_CC_EVT_ACK:
+		/* Do not increase the congestion window when already in recovery period. */
+		if (ev->ack.time_sent <= c->recovery_start_time)
+			goto out;
+
+		quic_cubic_update(cc, ev->ack.acked);
+		break;
+	case QUIC_CC_EVT_LOSS:
+		/* Do not decrease the congestion window when already in recovery period. */
+		if (ev->loss.time_sent <= c->recovery_start_time)
+			goto out;
+
+		quic_enter_recovery(cc);
+		break;
+	case QUIC_CC_EVT_ECN_CE:
+		/* TODO */
+		break;
+	}
+
+ out:
+	TRACE_LEAVE(QUIC_EV_CONN_CC, cc->qc, NULL, cc);
+}
+
+static void (*quic_cc_cubic_state_cbs[])(struct quic_cc *cc,
+                                      struct quic_cc_event *ev) = {
+	[QUIC_CC_ST_SS] = quic_cc_cubic_ss_cb,
+	[QUIC_CC_ST_CA] = quic_cc_cubic_ca_cb,
+};
+
+static void quic_cc_cubic_event(struct quic_cc *cc, struct quic_cc_event *ev)
+{
+	return quic_cc_cubic_state_cbs[cc->algo->state](cc, ev);
+}
+
+static void quic_cc_cubic_state_trace(struct buffer *buf, const struct quic_cc *cc)
+{
+}
+
+struct quic_cc_algo quic_cc_algo_cubic = {
+	.type        = QUIC_CC_ALGO_TP_CUBIC,
+	.init        = quic_cc_cubic_init,
+	.event       = quic_cc_cubic_event,
+	.slow_start  = quic_cc_cubic_slow_start,
+	.state_trace = quic_cc_cubic_state_trace,
+};