Update the README file to reflect the current state of the project.

Make formatting linux conform

See merge request lukas.prause/tcp-roccet-kernel-module!1

README.md

@@ -1,35 +1,40 @@
 # TCP ROCCET :rocket: (RTT Oriented CUBIC Congestion control ExTension)
 
-TCP ROCCET is a new TCP congestion control
-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.
+TCP ROCCET is a new TCP congestion control algorithm that reduces latency by detecting queuing.
+Additionally, it is specially suited for 4G/5G cellular networks.
 
-NOTE: A paper for TCP ROCCET is currently under review.
-Paper draft:
-            https://arxiv.org/abs/2510.25281
+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.
 
-The oldest Linux kernel version we tested with ROCCET is 6.1.
+## Install with apt
+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
+```
 
-## Setup
+### 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 reinstalling the kernel-headers.
+In case you get the "Invalid module Format" error, it can help to reinstall the kernel-headers.
 
 **2.** Use the Algorithm:
 * Either via globally loading it: `sudo sysctl net.ipv4.tcp_congestion_control=roccet`
@@ -39,12 +44,12 @@ In case you get the "Invalid module Format" error, it can help reinstalling 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: 
 ```
@@ -69,7 +74,7 @@ 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.  
 
@@ -78,21 +83,7 @@ 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.c

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: GPL-2.0-only
+// SPDX-License-Identifier: GPL-2.0
 /*
  * TCP ROCCET: An RTT-Oriented CUBIC Congestion Control
  * Extension for 5G and Beyond Networks
@@ -14,8 +14,9 @@
  * CUBIC's window growth function and adds, based on RTT
  * and ACK rate, congestion events.
  *
- * NOTE: A paper for TCP ROCCET is currently under review.
- * A draft of this paper can be found here:
+ * A peer-reviewed paper on TCP ROCCET will be presented at the WONS 2026 conference.
+ * A draft of the paper is available here:
+ *		https://arxiv.org/abs/2510.25281
  *
  *
  * Further information about CUBIC:
@@ -71,30 +72,26 @@
 static int sr_rtt_upper_bound __read_mostly = 100;
 static int ack_rate_diff_ss __read_mostly = 10;
 static int ack_rate_diff_ca __read_mostly = 200;
-static int calculate_min_rtt __read_mostly = 0;
-static int ignore_loss __read_mostly = 0;
-static int roccet_minRTT_interpolation_factor __read_mostly = 70;
+static bool calculate_min_rtt __read_mostly;
+static bool ignore_loss __read_mostly;
+static int roccet_min_rtt_interpolation_factor __read_mostly = 70;
 
 module_param(sr_rtt_upper_bound, int, 0644);
 MODULE_PARM_DESC(sr_rtt_upper_bound, "ROCCET's upper bound for srRTT.");
 module_param(ack_rate_diff_ss, int, 0644);
 MODULE_PARM_DESC(ack_rate_diff_ss,
-		 "ROCCET's threshold to exit slow start if ACK-rate defer by "
-		 "given amount of segments.");
+		 "ROCCET's threshold to exit slow start if ACK-rate defer by given amount of segments.");
 module_param(ack_rate_diff_ca, int, 0644);
 MODULE_PARM_DESC(ack_rate_diff_ca,
-		 "ROCCET's threshold for ack-rate and cum_cwnd, in percantage "
-		 "of the current cwnd.");
-module_param(calculate_min_rtt, int, 0644);
+		 "ROCCET's threshold for ack-rate and cum_cwnd, in percantage of the current cwnd.");
+module_param(calculate_min_rtt, bool, 0644);
 MODULE_PARM_DESC(calculate_min_rtt,
 		 "Calculate min RTT if no lower RTT occurs after 10 sec.");
-module_param(ignore_loss, int, 0644);
+module_param(ignore_loss, bool, 0644);
 MODULE_PARM_DESC(ignore_loss, "Ignore loss as a congestion event.");
-module_param(roccet_minRTT_interpolation_factor, int, 0644);
-MODULE_PARM_DESC(
-	roccet_minRTT_interpolation_factor,
-	"ROCCET factor for interpolating the current RTT with the last minRTT "
-	"(minRTT = (factor * currRTT + (100-factor) * minRTT) / 100)");
+module_param(roccet_min_rtt_interpolation_factor, int, 0644);
+MODULE_PARM_DESC(roccet_min_rtt_interpolation_factor,
+		 "ROCCET factor for interpolating the current RTT with the last minRTT (minRTT = (factor * currRTT + (100-factor) * minRTT) / 100)");
 
 static int fast_convergence __read_mostly = 1;
 static int beta __read_mostly = 717; /* = 717/1024 (BICTCP_BETA_SCALE) */
@@ -114,8 +111,7 @@ MODULE_PARM_DESC(beta, "beta for multiplicative increase");
 module_param(initial_ssthresh, int, 0644);
 MODULE_PARM_DESC(initial_ssthresh, "initial value of slow start threshold");
 module_param(bic_scale, int, 0444);
-MODULE_PARM_DESC(
-	bic_scale,
+MODULE_PARM_DESC(bic_scale,
 		 "scale (scaled by 1024) value for bic function (bic_scale/1024)");
 module_param(tcp_friendliness, int, 0644);
 MODULE_PARM_DESC(tcp_friendliness, "turn on/off tcp friendliness");
@@ -129,6 +125,7 @@ static inline void roccettcp_reset(struct roccettcp *ca)
 	ca->curr_min_rtt_timed.rtt = ~0U;
 	ca->curr_min_rtt_timed.time = ~0U;
 	ca->last_rtt = 0;
+	ca->ece_received = false;
 }
 
 static inline void update_min_rtt(struct sock *sk)
@@ -143,9 +140,9 @@ static inline void update_min_rtt(struct sock *sk)
 		u32 old_min_rtt = ca->curr_min_rtt_timed.rtt;
 
 		u32 interpolated_min_rtt =
-			(new_min_rtt * roccet_minRTT_interpolation_factor +
+			(new_min_rtt * roccet_min_rtt_interpolation_factor +
 			 old_min_rtt *
-				 (100 - roccet_minRTT_interpolation_factor)) /
+				 (100 - roccet_min_rtt_interpolation_factor)) /
 			100;
 
 		ca->curr_min_rtt_timed.rtt = interpolated_min_rtt;
@@ -196,13 +193,12 @@ static inline void update_srrtt(struct sock *sk)
 	/* Calculate the new rRTT (Scaled by 100).
 	 * 100 * ((sRTT - sRTT_min) / sRTT_min)
 	 */
-	u32 rRTT = (100 * (ca->curr_rtt - ca->curr_min_rtt_timed.rtt)) /
+	u32 rrtt = (100 * (ca->curr_rtt - ca->curr_min_rtt_timed.rtt)) /
 		   ca->curr_min_rtt_timed.rtt;
 
 	// (1 - alpha) * srRTT + alpha * rRTT
-	ca->curr_srRTT = ((100 - ROCCET_ALPHA_TIMES_100) * ca->curr_srRTT +
-			  ROCCET_ALPHA_TIMES_100 * rRTT) /
-			 100;
+	ca->curr_srrtt = ((100 - ROCCET_ALPHA_TIMES_100) * ca->curr_srrtt +
+			  ROCCET_ALPHA_TIMES_100 * rrtt) / 100;
 }
 
 __bpf_kfunc static void roccettcp_init(struct sock *sk)
@@ -214,7 +210,7 @@ __bpf_kfunc static void roccettcp_init(struct sock *sk)
 	if (initial_ssthresh)
 		tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
 
-	/* Initial roccet paramters */
+	/* Initial roccet parameters */
 	ca->roccet_last_event_time_us = 0;
 	ca->curr_min_rtt = ~0U;
 	ca->ack_rate.last_rate = 0;
@@ -338,7 +334,7 @@ static inline void bictcp_update(struct roccettcp *ca, u32 cwnd, u32 acked)
 	 * (so time^3 is done by using 64 bit)
 	 * and without the support of division of 64bit numbers
 	 * (so all divisions are done by using 32 bit)
-	 *  also NOTE the unit of those veriables
+	 *  also NOTE the unit of those variables
 	 *	  time  = (t - K) / 2^bictcp_HZ
 	 *	  c = bic_scale >> 10
 	 * rtt  = (srtt >> 3) / HZ
@@ -366,11 +362,10 @@ static inline void bictcp_update(struct roccettcp *ca, u32 cwnd, u32 acked)
 		bic_target = ca->bic_origin_point + delta;
 
 	/* cubic function - calc bictcp_cnt*/
-	if (bic_target > cwnd) {
+	if (bic_target > cwnd)
 		ca->cnt = cwnd / (bic_target - cwnd);
-	} else {
+	else
 		ca->cnt = 100 * cwnd; /* very small increment*/
-	}
 
 	/* The initial growth of cubic function may be too conservative
 	 * when the available bandwidth is still unknown.
@@ -413,13 +408,13 @@ __bpf_kfunc static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
 	u32 bw_limit_detect = 0;
 	u32 roccet_xj;
 	u32 jitter;
-	if (ca->last_rtt > ca->curr_rtt) {
-		jitter = ca->last_rtt - ca->curr_rtt;
-	} else {
-		jitter = ca->curr_rtt - ca->last_rtt;
-	}
 
-	/* Update roccet paramters */
+	if (ca->last_rtt > ca->curr_rtt)
+		jitter = ca->last_rtt - ca->curr_rtt;
+	else
+		jitter = ca->curr_rtt - ca->last_rtt;
+
+	/* Update roccet parameters */
 	update_ack_rate(sk);
 	update_min_rtt(sk);
 	update_srrtt(sk);
@@ -430,15 +425,19 @@ __bpf_kfunc static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
 	if (now - ca->roccet_last_event_time_us <= 100 * USEC_PER_MSEC)
 		return;
 
-	/* Lift off: Detect an exit point for tcp slow start
+	/* LAUNCH: Detect an exit point for tcp slow start
 	 * in networks with large buffers of multiple BDP
 	 * Like in cellular networks (5G, ...).
+	 * Or exit LAUNCH if cwnd is too large for application layer
+	 * data rate.
 	 */
-	if (tcp_in_slow_start(tp) && ca->curr_srRTT > sr_rtt_upper_bound &&
-	    get_ack_rate_diff(ca) >= ack_rate_diff_ss) {
+
+	if ((tcp_in_slow_start(tp) && ca->curr_srrtt > sr_rtt_upper_bound &&
+	     get_ack_rate_diff(ca) >= ack_rate_diff_ss) ||
+	    (!tcp_is_cwnd_limited(sk) && tcp_in_slow_start(tp))) {
 		ca->epoch_start = 0;
 
-		/* Handle inital slow start. Here we observe the most problems */
+		/* Handle initial slow start. Here we observe the most problems */
 		if (tp->snd_ssthresh == TCP_INFINITE_SSTHRESH) {
 			tcp_sk(sk)->snd_ssthresh = tcp_snd_cwnd(tp) / 2;
 			tcp_snd_cwnd_set(tp, tcp_snd_cwnd(tp) / 2);
@@ -486,7 +485,9 @@ __bpf_kfunc static void roccettcp_cong_avoid(struct sock *sk, u32 ack,
 	if (roccet_xj < sr_rtt_upper_bound)
 		roccet_xj = sr_rtt_upper_bound;
 
-	if (ca->curr_srRTT > roccet_xj && bw_limit_detect) {
+	if (ca->curr_srrtt > roccet_xj && (bw_limit_detect || ca->ece_received)) {
+		if (ca->ece_received)
+			ca->ece_received = false;
 		ca->epoch_start = 0;
 		ca->roccet_last_event_time_us = now;
 		ca->cnt = 100 * tcp_snd_cwnd(tp);
@@ -543,6 +544,7 @@ __bpf_kfunc static u32 roccettcp_recalc_ssthresh(struct sock *sk)
 __bpf_kfunc static void roccettcp_state(struct sock *sk, u8 new_state)
 {
 	struct roccettcp *ca = inet_csk_ca(sk);
+
 	if (new_state == TCP_CA_Loss)
 		roccettcp_reset(ca);
 }
@@ -561,6 +563,7 @@ __bpf_kfunc static void roccettcp_acked(struct sock *sk,
 		return;
 
 	u32 delay = sample->rtt_us;
+
 	if (delay == 0)
 		delay = 1;
 
@@ -575,6 +578,17 @@ __bpf_kfunc static void roccettcp_acked(struct sock *sk,
 	}
 }
 
+__bpf_kfunc static void roccet_in_ack_event(struct sock *sk, u32 flags)
+{
+	struct roccettcp *ca = inet_csk_ca(sk);
+
+	/* Handle ECE bit.
+	 * Processing of ECE events is done in roccettcp_cong_avoid()
+	 */
+	if (flags & CA_ACK_ECE)
+		ca->ece_received = true;
+}
+
 static struct tcp_congestion_ops roccet_tcp __read_mostly = {
 	.init = roccettcp_init,
 	.ssthresh = roccettcp_recalc_ssthresh,
@@ -583,6 +597,7 @@ static struct tcp_congestion_ops roccet_tcp __read_mostly = {
 	.undo_cwnd = tcp_reno_undo_cwnd,
 	.cwnd_event = roccettcp_cwnd_event,
 	.pkts_acked = roccettcp_acked,
+	.in_ack_event   = roccet_in_ack_event,
 	.owner = THIS_MODULE,
 	.name = "roccet",
 };

tcp_roccet.h

@@ -1,3 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * TCP ROCCET congestion control interface
  */
@@ -6,21 +7,21 @@
 
 #include <linux/math64.h>
 
-struct AckRate {
+struct ack_rate {
 	u16 last_rate;	/* Last ACK-rate */
 	u32 last_rate_time;	/* Timestamp of the last ACK-rate */
 	u16 curr_rate;	/* Current ACK-rate */
 	u16 cnt;	/* Used for counting acks */
 };
 
-struct BandwidthLimitDetect {
+struct bandwidth_limit_detect {
 	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 */
+struct timed_rtt {
+	u32 time;	/* Time of recording */
 	u32 rtt;	/* Measured RTT */
 };
 
@@ -32,20 +33,23 @@ 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;		/* the minimum rtt of current round */
 
-	u32 roccet_last_event_time_us; 	/* The last time ROCCETv2 was triggered */
+	u32 roccet_last_event_time_us;	/* The last time ROCCET was triggered */
+	bool ece_received;	/* Set to true if an ECE bit was received */
 	u32 curr_min_rtt;		/* The current observed minRTT */
-	struct TimedRTT curr_min_rtt_timed; /* The current observed minRTT with 
-						the timestamp when it was observed */
-	u32 curr_srRTT; 		/* The srRTT calculated based on the latest ACK */
-	struct AckRate ack_rate; 	/* The last and the current ACK rate */
-	struct BandwidthLimitDetect bw_limit;
+	struct timed_rtt curr_min_rtt_timed;	/* The current observed minRTT with
+						 * the timestamp when it was observed
+						 */
+	u32 curr_srrtt;			/* The srRTT calculated based on the latest ACK */
+	struct ack_rate ack_rate;	/* The last and the current ACK rate */
+	struct bandwidth_limit_detect bw_limit;
 	u32 last_rtt;			/* Used for jitter calculation */
 };