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Subject[PATCH] Adding Agile-SD TCP module and modifying Kconfig and Makefile to configure the kernel for this new module to configure the kernel for this new module.
Date
From: Mohamed Alrshah <mohamed.asnd@gmail.com>

---
net/ipv4/Kconfig | 15 ++++
net/ipv4/Makefile | 1 +
net/ipv4/tcp_agilesd.c | 221 +++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 237 insertions(+)
create mode 100755 net/ipv4/tcp_agilesd.c

diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 91a25579..22d824b1 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -677,6 +677,17 @@ config TCP_CONG_BBR
bufferbloat, policers, or AQM schemes that do not provide a delay
signal. It requires the fq ("Fair Queue") pacing packet scheduler.

+config TCP_CONG_AGILESD
+ tristate "Agile-SD Congestion control"
+ default n
+ ---help---
+
+ This is version 1.0 of Agile-SD TCP. It is a sender-side only.
+ It contributes the Agility Factor (AF) to shorten the epoch time
+ and to make TCP independent from RTT. AF reduces the sensitivity
+ to packet losses, which in turn Agile-SD to achieve better throughput
+ over high-speed networks.
+
choice
prompt "Default TCP congestion control"
default DEFAULT_CUBIC
@@ -713,6 +724,9 @@ choice

config DEFAULT_BBR
bool "BBR" if TCP_CONG_BBR=y
+
+ config DEFAULT_AGILESD
+ bool "AGILESD" if TCP_CONG_AGILESD=y

config DEFAULT_RENO
bool "Reno"
@@ -738,6 +752,7 @@ config DEFAULT_TCP_CONG
default "dctcp" if DEFAULT_DCTCP
default "cdg" if DEFAULT_CDG
default "bbr" if DEFAULT_BBR
+ default "agilesd" if DEFAULT_AGILESD
default "cubic"

config TCP_MD5SIG
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index f83de23a..33d398b5 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o
obj-$(CONFIG_INET_RAW_DIAG) += raw_diag.o
obj-$(CONFIG_NET_TCPPROBE) += tcp_probe.o
obj-$(CONFIG_TCP_CONG_BBR) += tcp_bbr.o
+obj-$(CONFIG_TCP_CONG_AGILESD) += tcp_agilesd.o
obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
obj-$(CONFIG_TCP_CONG_CDG) += tcp_cdg.o
obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o
diff --git a/net/ipv4/tcp_agilesd.c b/net/ipv4/tcp_agilesd.c
new file mode 100755
index 00000000..fd040ff2
--- /dev/null
+++ b/net/ipv4/tcp_agilesd.c
@@ -0,0 +1,221 @@
+/* agilesd is a Loss-Based Congestion Control Algorithm for TCP v1.0.
+ * agilesd has been created by Mohamed A. Alrshah,
+ * at Faculty of Computer Science and Information Technology,
+ * Universiti Putra Malaysia.
+ * agilesd is based on the article, which is published in 2015 as below:
+ *
+ * Alrshah, M.A., Othman, M., Ali, B. and Hanapi, Z.M., 2015.
+ * Agile-SD: a Linux-based TCP congestion control algorithm for supporting high-speed and short-distance networks.
+ * Journal of Network and Computer Applications, 55, pp.181-190.
+ */
+
+/* These includes are very important to operate the algorithm under NS2. */
+//#define NS_PROTOCOL "tcp_agilesd.c"
+//#include "../ns-linux-c.h"
+//#include "../ns-linux-util.h"
+//#include <math.h>
+/* These includes are very important to operate the algorithm under NS2. */
+
+/* These includes are very important to operate the algorithm under Linux OS. */
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/math64.h>
+#include <net/tcp.h>
+//#include <linux/skbuff.h> // optional
+//#include <linux/inet_diag.h> // optional
+/* These includes are very important to operate the algorithm under Linux OS. */
+
+#define SCALE 1000 /* Scale factor to avoid fractions */
+#define Double_SCALE 1000000 /* Double_SCALE must be equal to SCALE^2 */
+#define beta 900 /* beta for multiplicative decrease */
+
+static int initial_ssthresh __read_mostly;
+//static int beta __read_mostly = 900; /*the initial value of beta is equal to 90%*/
+
+module_param(initial_ssthresh, int, 0644);
+MODULE_PARM_DESC(initial_ssthresh, "initial value of slow start threshold");
+//module_param(beta, int, 0444);
+//MODULE_PARM_DESC(beta, "beta for multiplicative decrease");
+
+/* agilesd Parameters */
+struct agilesdtcp {
+ u32 loss_cwnd; // congestion window at last loss.
+ u32 frac_tracer; // This is to trace the fractions of the increment.
+ u32 degraded_loss_cwnd; // loss_cwnd after degradation.
+ enum dystate{SS=0, CA=1} agilesd_tcp_status;
+};
+
+static inline void agilesdtcp_reset(struct sock *sk)
+{
+ /*After timeout loss cntRTT and baseRTT must be reset to the initial values as below */
+}
+
+/* This function is called after the first acknowledgment is received and before the congestion
+ * control algorithm will be called for the first time. If the congestion control algorithm has
+ * private data, it should initialize its private date here. */
+static void agilesdtcp_init(struct sock *sk)
+{
+ struct agilesdtcp *ca = inet_csk_ca(sk);
+
+ // If the value of initial_ssthresh is not set, snd_ssthresh will be initialized by a large value.
+ if (initial_ssthresh)
+ tcp_sk(sk)->snd_ssthresh = initial_ssthresh;
+ else
+ tcp_sk(sk)->snd_ssthresh = 0x7fffffff;
+
+ ca->loss_cwnd = 0;
+ ca->frac_tracer = 0;
+ ca->agilesd_tcp_status = SS;
+}
+
+/* This function is called whenever an ack is received and the congestion window can be increased.
+ * This is equivalent to opencwnd in tcp.cc.
+ * ack is the number of bytes that are acknowledged in the latest acknowledgment;
+ * rtt is the the rtt measured by the latest acknowledgment;
+ * in_flight is the packet in flight before the latest acknowledgment;
+ * good_ack is an indicator whether the current situation is normal (no duplicate ack, no loss and no SACK). */
+static void agilesdtcp_cong_avoid(struct sock *sk, u32 ack, u32 in_flight) //For Linux Kernel Use.
+//static void agilesdtcp_cong_avoid(struct sock *sk, u32 ack, u32 seq_rtt, u32 in_flight, int data_acked) //For NS2 Use.
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct agilesdtcp *ca = inet_csk_ca(sk);
+ u32 inc_factor;
+ u32 ca_inc;
+ u32 current_gap, total_gap;
+ /* The value of inc_factor is limited by lower_fl and upper_fl.
+ * The lower_fl must be always = 1. The greater the upper_fl the higher the aggressiveness.
+ * But, if upper_fl set to 1, agilesd will work exactly as newreno.
+ * We have already designed an equation to calculate the optimum upper_fl based on the given beta.
+ * This equation will be revealed once its article is published*/
+ u32 lower_fl = 1 * SCALE;
+ u32 upper_fl = 3 * SCALE;
+
+ //if (!tcp_is_cwnd_limited(sk, in_flight)) return; //For NS-2 Use, if the in flight packets not >= cwnd do nothing//
+ if (!tcp_is_cwnd_limited(sk)) return; // For Linux Kernel Use.
+
+ if (tp->snd_cwnd < tp->snd_ssthresh){
+ ca->agilesd_tcp_status = SS;
+ //tcp_slow_start(tp); //For NS-2 Use
+ tcp_slow_start(tp, in_flight); // For Linux Kernel Use.
+ }
+ else {
+ ca->agilesd_tcp_status = CA;
+
+ if (ca->loss_cwnd > ca->degraded_loss_cwnd)
+ total_gap = ca->loss_cwnd - ca->degraded_loss_cwnd;
+ else
+ total_gap = 1;
+
+ if (ca->loss_cwnd > tp->snd_cwnd)
+ current_gap = ca->loss_cwnd - tp->snd_cwnd;
+ else
+ current_gap = 0;
+
+ inc_factor = min(max(((upper_fl * current_gap) / total_gap), lower_fl), upper_fl);
+
+ ca_inc = ((inc_factor * SCALE) / tp->snd_cwnd); /* SCALE is used to avoid fractions*/
+
+ ca->frac_tracer += ca_inc; /* This in order to take the fraction increase into account */
+ if (ca->frac_tracer >= Double_SCALE) /* To take factor scale into account */
+ {
+ tp->snd_cwnd += 1;
+ ca->frac_tracer -= Double_SCALE;
+ }
+ }
+}
+
+/* This function is called when the TCP flow detects a loss.
+ * It returns the slow start threshold of a flow, after a packet loss is detected. */
+static u32 agilesdtcp_recalc_ssthresh(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ struct agilesdtcp *ca = inet_csk_ca(sk);
+
+ ca->loss_cwnd = tp->snd_cwnd;
+
+ if (ca->agilesd_tcp_status == CA)
+ ca->degraded_loss_cwnd = max((tp->snd_cwnd * beta) / SCALE, 2U);
+ else
+ ca->degraded_loss_cwnd = max((tp->snd_cwnd * beta) / SCALE, 2U);
+
+ ca->frac_tracer = 0;
+
+ return ca->degraded_loss_cwnd;
+}
+
+/* This function is called when the TCP flow detects a loss.
+ * It returns the congestion window of a flow, after a packet loss is detected;
+ * (for many algorithms, this will be equal to ssthresh). When a loss is detected,
+ * min_cwnd is called after ssthresh. But some others algorithms might set min_cwnd
+ * to be smaller than ssthresh. If this is the case, there will be a slow start after loss recovery. */
+//static u32 agilesdtcp_min_cwnd(const struct sock *sk)
+//{
+// return tcp_sk(sk)->snd_ssthresh;
+//}
+
+static u32 agilesdtcp_undo_cwnd(struct sock *sk)
+{
+ const struct tcp_sock *tp = tcp_sk(sk);
+ const struct agilesdtcp *ca = inet_csk_ca(sk);
+ return max(tp->snd_cwnd, ca->loss_cwnd);
+}
+
+/* This function is called when the congestion state of the TCP is changed.
+ * newstate is the state code for the state that TCP is going to be in.
+ * The possible states are listed below:
+ * The current congestion control state, which can be one of the followings:
+ * TCP_CA_Open: normal state
+ * TCP_CA_Recovery: Loss Recovery after a Fast Transmission
+ * TCP_CA_Loss: Loss Recovery after a Timeout
+ * (The following two states are not effective in TCP-Linux but is effective in Linux)
+ * TCP_CA_Disorder: duplicate packets detected, but haven't reach the threshold. So TCP shall assume that packet reordering is happening.
+ * TCP_CA_CWR: the state that congestion window is decreasing (after local congestion in NIC, or ECN and etc).
+ * It is to notify the congestion control algorithm and is used by some
+ * algorithms which turn off their special control during loss recovery. */
+static void agilesdtcp_state(struct sock *sk, u8 new_state)
+{
+ if (new_state == TCP_CA_Loss)
+ agilesdtcp_reset(inet_csk_ca(sk));
+}
+
+/* This function is called when there is an acknowledgment that acknowledges some new packets.
+ * num_acked is the number of packets that are acknowledged by this acknowledgments. */
+//static void agilesdtcp_acked(struct sock *sk, u32 num_acked, ktime_t rtt_us) //For NS2 Use.
+static void agilesdtcp_acked(struct sock *sk, u32 num_acked, s32 rtt_us) //For Linux Kernel Use.
+{
+
+}
+
+static struct tcp_congestion_ops agilesdtcp __read_mostly = {
+ .init = agilesdtcp_init,
+ .ssthresh = agilesdtcp_recalc_ssthresh, //REQUIRED
+ .cong_avoid = agilesdtcp_cong_avoid, //REQUIRED
+ .set_state = agilesdtcp_state,
+ .undo_cwnd = agilesdtcp_undo_cwnd,
+ .pkts_acked = agilesdtcp_acked,
+ .owner = THIS_MODULE,
+ .name = "agilesd", //REQUIRED
+ //.min_cwnd = agilesdtcp_min_cwnd, //NOT REQUIRED
+};
+
+static int __init agilesdtcp_register(void)
+{
+ BUILD_BUG_ON(sizeof(struct agilesdtcp) > ICSK_CA_PRIV_SIZE);
+ return tcp_register_congestion_control(&agilesdtcp);
+}
+
+static void __exit agilesdtcp_unregister(void)
+{
+ tcp_unregister_congestion_control(&agilesdtcp);
+}
+
+module_init(agilesdtcp_register);
+module_exit(agilesdtcp_unregister);
+
+MODULE_AUTHOR("Mohamed A. Alrshah <mohamed.a.alrshah@ieee.org>");
+MODULE_AUTHOR("Mohamed Othman");
+MODULE_AUTHOR("Borhanuddin Ali");
+MODULE_AUTHOR("Zurina Hanapi");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_DESCRIPTION("agilesd is a Loss-Based Congestion Control Algorithm for TCP v1.0. By Mohamed A. Alrshah");
+MODULE_VERSION("1.0");
--
2.12.3
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