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Index: sys/netinet/cc/cc_cubic.c
===================================================================
--- sys/netinet/cc/cc_cubic.c
+++ sys/netinet/cc/cc_cubic.c
@@ -96,8 +96,58 @@
int epoch_ack_count;
/* Time of last congestion event in ticks. */
int t_last_cong;
+
+ /* Hybrid Slow Start values */
+
+ /* Minimum observed rtt in ms. */
+ int min_rtt_ms;
+ /* number of samples taken since start of packet train */
+ uint8_t sample_count;
+ /* an early exit condition for hybrid slow start has been found */
+ uint8_t exit_found;
+ /* start of hybrid slow start packet train */
+ uint32_t train_start;
+ /* value of snd_nxt at reset - used to determine ack value of next reset */
+ uint32_t end_seq;
+ /* millisecond granularity value of timestamp at the prior ack */
+ uint32_t last_ack;
+ /* the smallest measured RTT within the first HYSTART_MIN_SAMPLES (8) */
+ uint32_t curr_rtt;
+
+ /* assume hz == 1000 for first pass */
+ #define min_rtt_ms min_rtt_ticks
};
+#define USEC_PER_MSEC 1000
+
+#define HYSTART_ACK_TRAIN 0x1
+#define HYSTART_DELAY 0x2
+
+#define HYSTART_MIN_SAMPLES 8
+#define HYSTART_DELAY_MIN (4U<<3)
+#define HYSTART_DELAY_MAX (16U<<3)
+
+static inline int
+clamp(int x, int min, int max) {
+
+ if (x < min)
+ return min;
+ if (x > max)
+ return max;
+ return x;
+}
+
+#define HYSTART_DELAY_THRESH(x) clamp(x, HYSTART_DELAY_MIN, HYSTART_DELAY_MAX)
+
+
+SYSCTL_NODE(_net_inet_tcp_cc, OID_AUTO, cubic, CTLFLAG_RW, NULL,
+ "cubic congestion control related settings");
+
+//static int hystart = 1;
+static int hystart_detect = HYSTART_ACK_TRAIN | HYSTART_DELAY;
+static int hystart_low_window = 16;
+static int hystart_ack_delta = 2;
+
static MALLOC_DEFINE(M_CUBIC, "cubic data",
"Per connection data required for the CUBIC congestion control algorithm");
@@ -201,11 +251,11 @@
static int
cubic_cb_init(struct cc_var *ccv)
{
- struct cubic *cubic_data;
-
- cubic_data = malloc(sizeof(struct cubic), M_CUBIC, M_NOWAIT|M_ZERO);
+ struct cubic *cubic_data = ccv->cc_data;
if (cubic_data == NULL)
+ cubic_data = malloc(sizeof(struct cubic), M_CUBIC, M_NOWAIT|M_ZERO);
+ if (cubic_data == NULL)
return (ENOMEM);
/* Init some key variables with sensible defaults. */
@@ -218,6 +268,67 @@
return (0);
}
+static inline uint32_t
+cubic_clock(void)
+{
+ if (hz == 1000)
+ return (ticks);
+
+ return (((ticks + hz) * 1000)/hz);
+}
+
+static void
+cubic_hystart_init(struct cc_var *ccv)
+{
+ struct cubic *cd;
+
+ cd = ccv->cc_data;
+ cd->train_start = cd->last_ack = cubic_clock();
+ cd->end_seq = CCV(ccv, snd_nxt);
+ cd->curr_rtt = 0;
+ cd->sample_count = cd->exit_found = 0;
+}
+
+static void
+cubic_hystart_update(struct cc_var *ccv, uint32_t delay)
+{
+ struct cubic *cd;
+ uint32_t now;
+
+ cd = ccv->cc_data;
+
+ if (cd->exit_found & hystart_detect)
+ return;
+
+ if (CCV(ccv, snd_cwnd) < hystart_low_window)
+ return;
+
+ if (hystart_detect & HYSTART_ACK_TRAIN) {
+ now = cubic_clock();
+ if ((int32_t)(now - cd->last_ack) <= hystart_ack_delta) {
+ cd->last_ack = now;
+ if ((int32_t)(now - cd->train_start) > cd->min_rtt_ms >> 4) {
+ cd->exit_found |= HYSTART_ACK_TRAIN;
+ CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd);
+
+ }
+ }
+ }
+
+ if (hystart_detect & HYSTART_DELAY) {
+ if (cd->sample_count < HYSTART_MIN_SAMPLES) {
+ if (cd->curr_rtt == 0 || cd->curr_rtt > delay)
+ cd->curr_rtt = delay;
+ cd->sample_count++;
+ } else {
+ if (cd->curr_rtt > cd->min_rtt_ms + HYSTART_DELAY_THRESH(cd->min_rtt_ms >> 3)) {
+ cd->exit_found |= HYSTART_DELAY;
+ CCV(ccv, snd_ssthresh) = CCV(ccv, snd_cwnd);
+ }
+ }
+ }
+}
+
/*
* Perform any necessary tasks before we enter congestion recovery.
*/
@@ -360,10 +471,20 @@
{
struct cubic *cubic_data;
int t_srtt_ticks;
+ int rtt_us, rtt_s3_ms;
+
+ cubic_data = ccv->cc_data;
+ if (ccv->sample_rtt_us >= 0) {
+ rtt_us = ccv->sample_rtt_us;
+ rtt_s3_ms = (rtt_us << 3)/USEC_PER_MSEC;
+ if (SEQ_GT(ccv->curack, cubic_data->end_seq))
+ cubic_hystart_init(ccv);
+
+ cubic_hystart_update(ccv, rtt_s3_ms);
+ }
/* Ignore srtt until a min number of samples have been taken. */
if (CCV(ccv, t_rttupdated) >= CUBIC_MIN_RTT_SAMPLES) {
- cubic_data = ccv->cc_data;
t_srtt_ticks = CCV(ccv, t_srtt) / TCP_RTT_SCALE;
/*

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