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Index: head/sys/netinet/cc/cc_cubic.c
===================================================================
--- head/sys/netinet/cc/cc_cubic.c
+++ head/sys/netinet/cc/cc_cubic.c
@@ -78,7 +78,7 @@
static int cubic_mod_init(void);
static void cubic_post_recovery(struct cc_var *ccv);
static void cubic_record_rtt(struct cc_var *ccv);
-static void cubic_ssthresh_update(struct cc_var *ccv);
+static void cubic_ssthresh_update(struct cc_var *ccv, uint32_t maxseg);
static void cubic_after_idle(struct cc_var *ccv);
struct cubic {
@@ -90,19 +90,28 @@
unsigned long max_cwnd;
/* cwnd at the previous congestion event. */
unsigned long prev_max_cwnd;
+ /* A copy of prev_max_cwnd. Used for CC_RTO_ERR */
+ unsigned long prev_max_cwnd_cp;
/* various flags */
uint32_t flags;
#define CUBICFLAG_CONG_EVENT 0x00000001 /* congestion experienced */
#define CUBICFLAG_IN_SLOWSTART 0x00000002 /* in slow start */
#define CUBICFLAG_IN_APPLIMIT 0x00000004 /* application limited */
+#define CUBICFLAG_RTO_EVENT 0x00000008 /* RTO experienced */
/* Minimum observed rtt in ticks. */
int min_rtt_ticks;
/* Mean observed rtt between congestion epochs. */
int mean_rtt_ticks;
/* ACKs since last congestion event. */
int epoch_ack_count;
- /* Time of last congestion event in ticks. */
+ /* Timestamp (in ticks) of arriving in congestion avoidance from last
+ * congestion event.
+ */
int t_last_cong;
+ /* Timestamp (in ticks) of a previous congestion event. Used for
+ * CC_RTO_ERR.
+ */
+ int t_last_cong_prev;
};
static MALLOC_DEFINE(M_CUBIC, "cubic data",
@@ -142,7 +151,14 @@
cubic_data->flags |= CUBICFLAG_IN_SLOWSTART;
newreno_cc_algo.ack_received(ccv, type);
} else {
- if (cubic_data->flags & (CUBICFLAG_IN_SLOWSTART |
+ if ((cubic_data->flags & CUBICFLAG_RTO_EVENT) &&
+ (cubic_data->flags & CUBICFLAG_IN_SLOWSTART)) {
+ /* RFC8312 Section 4.7 */
+ cubic_data->flags &= ~(CUBICFLAG_RTO_EVENT |
+ CUBICFLAG_IN_SLOWSTART);
+ cubic_data->max_cwnd = CCV(ccv, snd_cwnd);
+ cubic_data->K = 0;
+ } else if (cubic_data->flags & (CUBICFLAG_IN_SLOWSTART |
CUBICFLAG_IN_APPLIMIT)) {
cubic_data->flags &= ~(CUBICFLAG_IN_SLOWSTART |
CUBICFLAG_IN_APPLIMIT);
@@ -273,10 +289,10 @@
case CC_NDUPACK:
if (!IN_FASTRECOVERY(CCV(ccv, t_flags))) {
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
- cubic_ssthresh_update(ccv);
+ cubic_ssthresh_update(ccv, mss);
cubic_data->flags |= CUBICFLAG_CONG_EVENT;
cubic_data->t_last_cong = ticks;
- cubic_data->K = cubic_k(cubic_data->max_cwnd / CCV(ccv, t_maxseg));
+ cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
}
ENTER_RECOVERY(CCV(ccv, t_flags));
}
@@ -284,37 +300,35 @@
case CC_ECN:
if (!IN_CONGRECOVERY(CCV(ccv, t_flags))) {
- cubic_ssthresh_update(ccv);
+ cubic_ssthresh_update(ccv, mss);
cubic_data->flags |= CUBICFLAG_CONG_EVENT;
cubic_data->t_last_cong = ticks;
- cubic_data->K = cubic_k(cubic_data->max_cwnd / CCV(ccv, t_maxseg));
+ cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
CCV(ccv, snd_cwnd) = CCV(ccv, snd_ssthresh);
ENTER_CONGRECOVERY(CCV(ccv, t_flags));
}
break;
case CC_RTO:
- CCV(ccv, snd_ssthresh) = max(min(CCV(ccv, snd_wnd),
- CCV(ccv, snd_cwnd)) / 2 / mss,
- 2) * mss;
- CCV(ccv, snd_cwnd) = mss;
- /*
- * Grab the current time and record it so we know when the
- * most recent congestion event was. Only record it when the
- * timeout has fired more than once, as there is a reasonable
- * chance the first one is a false alarm and may not indicate
- * congestion.
- * This will put Cubic firmly into the concave / TCP friendly
- * region, for a slower ramp-up after two consecutive RTOs.
- */
- if (CCV(ccv, t_rxtshift) >= 2) {
- cubic_data->flags |= CUBICFLAG_CONG_EVENT;
- cubic_data->t_last_cong = ticks;
- cubic_data->max_cwnd = CCV(ccv, snd_cwnd_prev);
- cubic_data->K = cubic_k(cubic_data->max_cwnd /
- CCV(ccv, t_maxseg));
+ /* RFC8312 Section 4.7 */
+ if (CCV(ccv, t_rxtshift) == 1) {
+ cubic_data->t_last_cong_prev = cubic_data->t_last_cong;
+ cubic_data->prev_max_cwnd_cp = cubic_data->prev_max_cwnd;
}
+ cubic_data->flags |= CUBICFLAG_CONG_EVENT | CUBICFLAG_RTO_EVENT;
+ cubic_data->prev_max_cwnd = cubic_data->max_cwnd;
+ CCV(ccv, snd_ssthresh) = ((uint64_t)CCV(ccv, snd_cwnd) *
+ CUBIC_BETA) >> CUBIC_SHIFT;
+ CCV(ccv, snd_cwnd) = mss;
break;
+
+ case CC_RTO_ERR:
+ cubic_data->flags &= ~(CUBICFLAG_CONG_EVENT | CUBICFLAG_RTO_EVENT);
+ cubic_data->max_cwnd = cubic_data->prev_max_cwnd;
+ cubic_data->prev_max_cwnd = cubic_data->prev_max_cwnd_cp;
+ cubic_data->t_last_cong = cubic_data->t_last_cong_prev;
+ cubic_data->K = cubic_k(cubic_data->max_cwnd / mss);
+ break;
}
}
@@ -436,7 +450,7 @@
* Update the ssthresh in the event of congestion.
*/
static void
-cubic_ssthresh_update(struct cc_var *ccv)
+cubic_ssthresh_update(struct cc_var *ccv, uint32_t maxseg)
{
struct cubic *cubic_data;
uint32_t ssthresh;
@@ -466,7 +480,7 @@
ssthresh = ((uint64_t)cwnd *
CUBIC_BETA) >> CUBIC_SHIFT;
}
- CCV(ccv, snd_ssthresh) = max(ssthresh, 2 * CCV(ccv, t_maxseg));
+ CCV(ccv, snd_ssthresh) = max(ssthresh, 2 * maxseg);
}
DECLARE_CC_MODULE(cubic, &cubic_cc_algo);

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