Adds ECN handling managed by ROCCET. Use of srRTT as a hard condition after receiving an ECN.

README.md

@@ -1,55 +1,35 @@
 # TCP ROCCET :rocket: (RTT Oriented CUBIC Congestion control ExTension)
 
-TCP ROCCET is a new TCP congestion control algorithm that reduces latency by detecting queuing.
+TCP ROCCET is a new TCP congestion control
-Additionally, it is specially suited for 4G/5G cellular networks.
+algorithm suited for current cellular 5G NR beyond networks.
+It extends the kernel default congestion control CUBIC
+and improves its performance, and additionally solves
+unwanted side effects of CUBIC’s implementation.
+ROCCET uses its own Slow Start, called LAUNCH, where loss
+is not considered as a congestion event.
+The congestion avoidance phase, called ORBITER, uses 
+CUBIC's window growth function and adds, based on RTT
+and ACK rate, congestion events.
 
-A peer-reviewed [paper on TCP ROCCET](https://opendl.ifip-tc6.org/db/conf/wons/wons2026/1571217211.pdf) was presented at the WONS 2026 conference.
+NOTE: A paper for TCP ROCCET is currently under review.
+Paper draft:
+            https://arxiv.org/abs/2510.25281
  
-A new performance report for the latest version of TCP ROCCET can be found under "doc/measurements/2026-07-21_performance-report.pdf".
+The oldest Linux kernel version we tested with ROCCET is 6.1.
 
-### Versions
+## Setup
 
-- latest on master branch (requires kernel version 7.1 or higher)
-    - Improved min RTT probing
-    - Packet pacing
-    - Code refactor
-    - Monitoring send and receive rate
-
-- release-2026-06-12-v1
-    - Adds minimum RTT probing
-    
-## Install with apt (requires kernel version 6.10 or higher)
-Add tcp-roccet-dkms to your source lists and install:
-
-```
-echo "deb [trusted=yes] https://apt.fury.io/timfuchs/ /" | sudo tee /etc/apt/sources.list.d/tcp-roccet.list
-sudo apt update
-sudo apt install tcp-roccet-dkms
-```
-
-### Loading and using the congestion control
-Note: This change is not persistent, the module will not be loaded at boot.
-
-```
-sudo modprobe tcp_roccet
-sudo sysctl net.ipv4.tcp_congestion_control=roccet
-```
-
-## Build from source
-
-### Setup
-Kernel headers are required:
 * Debian: `sudo apt install linux-headers-generic`
 * Fedora: `sudo dnf install kernel-devel`
 (`sudo reboot`)
 
-### Build 
+## Build 
 `make`
 
 
 ## Loading & Unloading the Module  
 **1.** Insert into Kernel: `sudo insmod tcp_roccet.ko`
-In case you get the "Invalid module Format" error, it can help to reinstall the kernel-headers.
+In case you get the "Invalid module Format" error, it can help reinstalling the kernel-headers.
 
 **2.** Use the Algorithm:
 * Either via globally loading it: `sudo sysctl net.ipv4.tcp_congestion_control=roccet`
@@ -59,12 +39,12 @@ In case you get the "Invalid module Format" error, it can help to reinstall the
 
 
 ## Debugging (Using kprobe)
-In order to debug the `tcp_roccet` congestion control algorithm, there exists a Kprobe module (`roccet_kprobe.c`). Using this, it is possible to inspect events generated by the algorithm. 
+In order to debug the `tcp_roccet` congestion control algorithm, there exists a Kprobe module (`roccet_kprobe.c`). Using this it is possible to inspect events generated by the algorithm. 
 
-In order to use the Kprobe module, the following steps are necessary: 
+In order to use the Kprobe module the following steps are necessary: 
 
 **1. Specify the event to inspect**
-For this, head into the `tcp_roccet.c` source code and find the function the Kprobe should attach to. 
+For this head into the `tcp_roccet.c` source code and find the function the Kprobe should attach to. 
 
 For Example: 
 ```
@@ -89,7 +69,7 @@ Required files for this are:
 * `tcp_roccet.c` (Optional; Need to remove corresponding entry in Makefile if missing)
 
 **3. Load Kprobe module**
-To then load the module use 
+To then load the Module use 
 `sudo insmod roccet_kprobe.ko` 
 If you are seeing the error "Unknown symbol in module" you need to first load the roccet algorithm.  
 
@@ -98,7 +78,21 @@ To see the trace output use
 `sudo cat /sys/kernel/tracing/trace_pipe`
 
 **5. Unload Kprobe module**
-To remove the module again, use 
+To remove the module again use 
 `sudo rmmod roccet_kprobe` 
 
 _See more info at_ https://docs.kernel.org/trace/kprobes.html and https://www.kernel.org/doc/Documentation/trace/kprobetrace.rst
+
+## Further Info
+* On TCP-CC Ops: 
+    * https://www.yonch.com/tech/linux-tcp-congestion-control-internals
+    * https://docs.ebpf.io/linux/program-type/BPF_PROG_TYPE_STRUCT_OPS/tcp_congestion_ops/
+
+# Setup Development Environment 
+For specific Kernel:  
+1. Download linux source (the version you want to develop for)
+2. Create Config via `make defconfig`
+3. Compile kernel via `make`
+4. Generate clangd Config via `python scripts/clang-tools/gen_compile_commands.py`
+5. Copy `compile_commands.json` to development directory  
+

tcp_roccet.h

@@ -1,4 +1,3 @@
-/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * TCP ROCCET congestion control interface
  */
@@ -7,19 +6,25 @@
 
 #include <linux/math64.h>
 
-/* State in which roccet currently operates */
+struct AckRate {
-enum roccet_state {
+	u16 last_rate;	/* Last ACK-rate */
-	LAUNCH,
+	u32 last_rate_time; /* Timestamp of the last ACK-rate */
-	ORBITER,
+	u16 curr_rate; 	/* Current ACK-rate */
-	RTT_PROBE_ENTER,
+	u16 cnt; 	/* Used for counting acks */
-	RTT_PROBE,
-	RTT_PROBE_REFILL,
-	DRAIN
 };
 
-/* TCP ROCCET struct based on the original BICTCP struct with
+struct BandwidthLimitDetect {
- * additions specific to the ROCCET-Algorithm.
+	u32 sum_cwnd; 	/* sum of cwnd during time interval */
- */
+	u32 sum_acked; 	/* sum of received acks during time interval */
+	u32 next_check; /* end/upper bound of time interval */
+};
+
+struct TimedRTT {
+	u32 time; /* Time of recoding */
+	u32 rtt;  /* Measured RTT */
+};
+
+/* Based on the BICTCP struct with additions specific for the ROCCET-Algorithm */
 struct roccettcp {
 	u32 cnt; 		/* increase cwnd by 1 after ACKs */
 	u32 last_max_cwnd; 	/* last maximum snd_cwnd */
@@ -27,51 +32,23 @@ struct roccettcp {
 	u32 last_time; 		/* time when updated last_cwnd */
 	u32 bic_origin_point; 	/* origin point of bic function */
 	u32 bic_K; 		/* time to origin point from the 
-			 * beginning of the current epoch
+				beginning of the current epoch */
-			 */
 	u32 delay_min; 		/* min delay (usec) */
 	u32 epoch_start; 	/* beginning of an epoch */
 	u32 ack_cnt; 		/* number of acks */
 	u32 tcp_cwnd; 		/* estimated tcp cwnd */
-	u32 curr_rtt;	/* last sample rtt of current round */
+	u32 curr_rtt; 		/* the minimum rtt of current round */
 
 	u32 roccet_last_event_time_us; 	/* The last time ROCCET was triggered */
+	u32 ece_cwnd; 	/* The cwnd when a ECE bit was received */
+	u32 ece_srrtt; 	/* The srRTT whent the ECE was received */
 	u32 curr_min_rtt; 		/* The current observed minRTT */
-	u32 next_min_rtt_probe;	/* Next time to probe the minRTT */
+	struct TimedRTT curr_min_rtt_timed; /* The current observed minRTT with 
-	u32 probe_min_rtt_until;	/* End of minRTT probing period.
+						the timestamp when it was observed */
-					 * Set while in RTT_PROBE states
+	u32 curr_srRTT; 		/* The srRTT calculated based on the latest ACK */
-					 */
+	struct AckRate ack_rate; 	/* The last and the current ACK rate */
-	u32 refill_until;	/* End of pipe refill after minRTT probe.
+	struct BandwidthLimitDetect bw_limit;
-				 * Set while in RTT_PROBE states
+	u32 last_rtt; 			/* Used for jitter calculation */
-				 */
-	u32 cwnd_before_min_rtt_probe;	/* cwnd before min RTT probing. */
-	u32 curr_srrtt;	/* srRTT calculated based on the latest ACK */
-	u32 next_srrtt_check_ts;	/* Next check for srRTT */
-	u32 last_rtt;	/* sample rtt of previous round.
-			 * Used for jitter calculation
-			 */
-
-	u32 interval_snd_seq_start;
-	u32 interval_una_seq_start;
-
-	u32 ack_rate_last_rate_time;	/* Timestamp of the last ACK-rate */
-	u16 ack_rate_last_rate;	/* Last ACK-rate */
-	u16 ack_rate_curr_rate;	/* Current ACK-rate */
-	u16 ack_rate_cnt;	/* Used for counting acks */
-
-	enum roccet_state state : 3; /* Current operating state of roccet */
-	bool was_idle : 1;	/* Tracks whether the connection was idle
-				 * (had no in-flight packets)
-				 */
-	bool initial_limit_reached: 1;	/* Set to true after the connection
-					 * initially gets cwnd-limited
-					 */
-	bool is_in_initial_launch: 1;	/* true if the connection is in
-					 * the initial launch phase.
-					 */
-	u32 ack_carry_over;	/* Used to carry over leftover acks from
-				 * LAUNCH to ORBITER
-				 */
 };
 
 #endif /* __TCP_ROCCET_H */