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XuyangCaoUCSDXuyangCaoUCSD
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add SaTCP git patch
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‎emulation_stage/satcp/README.md

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@@ -20,7 +20,7 @@ You can configure $D$ in `report_relay.c`. Simply modify the value of `SATCP_DUR
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### To Use SaTCP:
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1. Have the Linux kernel source codes. Replace `source/net/ipv4/tcp_cubic.c` with the one we provided. Compile and use the kernel.
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1. Have the Linux kernel source codes. Replace `source/net/ipv4/tcp_cubic.c` with the one we provided. Compile and use the kernel. Or you can try to apply the patch we provided `git apply satcp.patch` (may not be compatible).
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2. Make sure you select CUBIC as the TCP congestion control algorithm. In Ubuntu:
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```Bash
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$ sudo sysctl net.ipv4.tcp_congestion_control=cubic

‎emulation_stage/satcp/satcp.patch

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@@ -0,0 +1,122 @@
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diff --git a/net/ipv4/tcp_cubic.c b/net/ipv4/tcp_cubic.c
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index fffa011a007d..0acb98749f19 100644
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--- a/net/ipv4/tcp_cubic.c
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+++ b/net/ipv4/tcp_cubic.c
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@@ -29,11 +29,24 @@
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#include <linux/math64.h>
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#include <net/tcp.h>
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+#include <linux/fs.h>
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+#include <asm/segment.h>
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+#include <asm/uaccess.h>
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+#include <linux/buffer_head.h>
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+#include <linux/kthread.h>
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+#include <linux/irqflags.h>
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+#include <linux/kernel.h>
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+#include <linux/netlink.h>
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+#include <net/netlink.h>
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+#include <net/net_namespace.h>
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+
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#define BICTCP_BETA_SCALE 1024 /* Scale factor beta calculation
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* max_cwnd = snd_cwnd * beta
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*/
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#define BICTCP_HZ 10 /* BIC HZ 2^10 = 1024 */
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+#define NETLINK_TESTFAMILY 31
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+
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/* Two methods of hybrid slow start */
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#define HYSTART_ACK_TRAIN 0x1
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#define HYSTART_DELAY 0x2
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@@ -80,6 +93,41 @@ MODULE_PARM_DESC(hystart_low_window, "lower bound cwnd for hybrid slow start");
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module_param(hystart_ack_delta_us, int, 0644);
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MODULE_PARM_DESC(hystart_ack_delta_us, "spacing between ack's indicating train (usecs)");
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+struct sock *socket;
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+
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+bool handover_status = false;
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+
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+static void nl_receive_handover_status(struct sk_buff *skb) {
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+ struct nlmsghdr *nlh = (struct nlmsghdr *) skb->data;
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+ char *singal = (char*) nlmsg_data(nlh);
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+ if (singal[0] == '1') {
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+ handover_status = true;
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+ printk("handover status changed to 1\n");
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+ } else {
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+ handover_status = false;
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+ printk("handover status changed to 0\n");
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+ }
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+}
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+
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+static int socket_init(void) {
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+ struct netlink_kernel_cfg config = {
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+ .input = nl_receive_handover_status,
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+ };
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+
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+ socket = netlink_kernel_create(&init_net, NETLINK_TESTFAMILY, &config);
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+ if (socket == NULL) {
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+ return -1;
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+ }
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+
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+ return 0;
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+}
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+
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+static void socket_exit(void) {
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+ if (socket) {
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+ netlink_kernel_release(socket);
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+ }
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+}
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+
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/* BIC TCP Parameters */
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struct bictcp {
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u32 cnt; /* increase cwnd by 1 after ACKs */
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@@ -251,8 +299,15 @@ static inline void bictcp_update(struct bictcp *ca, u32 cwnd, u32 acked)
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/* Compute new K based on
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* (wmax-cwnd) * (srtt>>3 / HZ) / c * 2^(3*bictcp_HZ)
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*/
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- ca->bic_K = cubic_root(cube_factor
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- * (ca->last_max_cwnd - cwnd));
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+ // shrink the recovery time
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+ if (handover_status) {
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+ // handover is happening, so drastically reduce the recovery time K to last max point
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+ ca->bic_K = cubic_root(cube_factor * (ca->last_max_cwnd - cwnd)) - (cubic_root(cube_factor * (ca->last_max_cwnd - cwnd)) * 8 / 9);
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+ printk("SATCP triggered in bictcp_update!\n");
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+ } else {
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+ ca->bic_K = cubic_root(cube_factor * (ca->last_max_cwnd - cwnd));
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+ }
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+
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ca->bic_origin_point = ca->last_max_cwnd;
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}
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}
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@@ -364,9 +419,14 @@ static u32 bictcp_recalc_ssthresh(struct sock *sk)
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static void bictcp_state(struct sock *sk, u8 new_state)
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{
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+ // ignore packet loss
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if (new_state == TCP_CA_Loss) {
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- bictcp_reset(inet_csk_ca(sk));
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- bictcp_hystart_reset(sk);
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+ if (!handover_status) {
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+ bictcp_reset(inet_csk_ca(sk));
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+ bictcp_hystart_reset(sk);
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+ } else {
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+ printk("SATCP triggered in bictcp_state!\n");
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+ }
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}
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}
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@@ -494,6 +554,7 @@ static struct tcp_congestion_ops cubictcp __read_mostly = {
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static int __init cubictcp_register(void)
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{
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+ socket_init();
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BUILD_BUG_ON(sizeof(struct bictcp) > ICSK_CA_PRIV_SIZE);
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/* Precompute a bunch of the scaling factors that are used per-packet
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@@ -530,6 +591,7 @@ static int __init cubictcp_register(void)
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static void __exit cubictcp_unregister(void)
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{
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tcp_unregister_congestion_control(&cubictcp);
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+ socket_exit();
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}
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module_init(cubictcp_register);

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