Adds send and receive rate monitoring.

README.md

@@ -11,6 +11,7 @@ A peer-reviewed [paper on TCP ROCCET](https://opendl.ifip-tc6.org/db/conf/wons/w
     - Improved min RTT probing
     - Packet pacing
     - Code refactor
+    - Monitoring send and receive rate
 
 - release-2026-06-12-v1
     - Adds minimum RTT probing

tcp_roccet.c

@@ -230,11 +230,14 @@ static __always_inline void roccet_congestion_event(struct sock *sk, u32 now)
 	ca->epoch_start = 0;
 	ca->roccet_last_event_time_us = now;
 	ca->cnt = 100 * tcp_snd_cwnd(tp);
-	ca->last_max_cwnd = tcp_snd_cwnd(tp);
-	tcp_snd_cwnd_set(tp, min(tp->snd_cwnd_clamp,
-				 max((tcp_snd_cwnd(tp) * beta) /
-				      BICTCP_BETA_SCALE, 2U)));
-	tp->snd_ssthresh = tcp_snd_cwnd(tp);
+    /*Set W_max only if the current cwnd is larger */
+    if (tcp_snd_cwnd(tp) > ca->last_max_cwnd)
+            ca->last_max_cwnd = tcp_snd_cwnd(tp);
+    tcp_snd_cwnd_set(tp, min(tp->snd_cwnd_clamp,
+                                max((tcp_snd_cwnd(tp) * beta) /
+                                    BICTCP_BETA_SCALE, 2U)));
+    tp->snd_ssthresh = tcp_snd_cwnd(tp);
+
 }
 
 /* Do minimum RTT probing.
@@ -497,8 +500,10 @@ static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
 
 	u32 now = jiffies_to_usecs(tcp_jiffies32);
 	bool evaluate_srrtt = false;
+    bool send_more_than_acked = false;
 	u32 roccet_xj;
 	u32 jitter;
+    u32 send, received;
 
     if(ca->state == LAUNCH){
     /* LAUNCH: Detect an exit point for tcp slow start
@@ -539,10 +544,11 @@ static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
             return;
 
     }else if(ca->state == ORBITER){
-    /* ORBITER: Increase the cwnd by using the CUBIC
-     * cwnd growth function, if no roccet congestion
-     * event is detechted.
-	 */
+        /* ORBITER: Increase the cwnd by using the CUBIC
+        * cwnd growth function, if no roccet congestion
+        * event is detechted.
+        */
+
         /* Calculate jitter */
         if ((s32)(ca->curr_rtt - ca->last_rtt) < 0)
             jitter = ca->last_rtt - ca->curr_rtt;
@@ -552,12 +558,38 @@ static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
         if (ca->next_srrtt_check == 0)
             ca->next_srrtt_check = now + 5 * ca->curr_rtt;
 
+        /* Calculate if more bytes was send than reveived
+            * in the time interval.
+            */
+        if (tp->snd_nxt < ca->interval_snd_seq_start){
+            /* We had a wrap around in seq no counter */
+            send = (~0U - ca->interval_snd_seq_start + tp->snd_nxt);
+        }else{
+            send = (tp->snd_nxt - ca->interval_snd_seq_start);
+        }
+        if (tp->snd_una < ca->interval_una_seq_start){
+            /* We had a wrap around in seq no counter */
+            received = (~0U - ca->interval_una_seq_start + tp->snd_una);
+        }else{
+            received = (tp->snd_una - ca->interval_una_seq_start);
+        }
+
+        /* Here we use a guard space of 1% of the current cwnd.
+        * We do this to avoid a false positive evaluation due
+        * to delays caused by jitter or scheduling.
+        */
+        send_more_than_acked = send > received + ((tcp_snd_cwnd(tp) * tp->mss_cache) / 100 );
+
         /* Check if it's time to evaluate the srRTT */
         if ((s32)(ca->next_srrtt_check - now) < 0) {
             evaluate_srrtt = true;
 
             /* reset struct and set next end of period */
             ca->next_srrtt_check = now + 5 * ca->curr_rtt;
+
+            /* Reset Rate calculation */
+            ca->interval_snd_seq_start = tp->snd_nxt;
+            ca->interval_una_seq_start = tp->snd_una;
         }
 
         /* Respects the jitter of the connection and add it on top of
@@ -571,7 +603,7 @@ static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
         /* The srRTT exceeds the upper bound if bufferbloat happens.
         * Here, we want to reduce the cwnd and drain the buffer.
         */
-        if (ca->curr_srrtt > roccet_xj && evaluate_srrtt) {
+        if (ca->curr_srrtt > roccet_xj && evaluate_srrtt && send_more_than_acked) {
             roccet_congestion_event(sk, now);
             return;
         }
@@ -583,7 +615,7 @@ static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
         * at an excessively high value. The cwnd cannot therefore be fully
         * utilized because it is limited by the connection capacity.
         */
-        if (!tcp_is_cwnd_limited(sk))
+        if (!tcp_is_cwnd_limited(sk) || send_more_than_acked)
             return;
 
         bictcp_update(ca, tcp_snd_cwnd(tp), acked);
@@ -727,6 +759,12 @@ __bpf_kfunc static void roccet_control(struct sock *sk, u32 ack, int flag, const
 	update_min_rtt(sk);
 	update_srrtt(sk);
 
+    /* Set values for send and receive rate */
+    if (ca->interval_snd_seq_start == 0){
+        ca->interval_snd_seq_start = tp->snd_nxt;
+        ca->interval_una_seq_start = tp->snd_una;
+    }
+
     /* Update roccet state */
     if(tcp_in_slow_start(tp)){
         ca->state = LAUNCH;

tcp_roccet.h

@@ -58,6 +58,8 @@ struct roccettcp {
 					 * Used for jitter calculation
 					 */
     enum roccet_state state; /* State in which roccet currently opperates */
+    u32 interval_snd_seq_start;
+    u32 interval_una_seq_start;
 };
 
 #endif /* __TCP_ROCCET_H */