├── Makefile
├── README.md
└── tcp_elastic.c


/Makefile:
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 1 | obj-m += tcp_elastic.o
 2 | 
 3 | all:
 4 | 	make -C /lib/modules/`uname -r`/build M=`pwd` modules
 5 | install:
 6 | 	make -C /lib/modules/`uname -r`/build M=`pwd` modules_install
 7 | clean:
 8 | 	rm -f \
 9 | 		*.ko \
10 | 		.*.o.cmd \
11 | 		*.o \
12 | 		*.mod.c \
13 | 		Module.symvers \
14 | 		.*.mod.cmd \
15 | 		modules.order \
16 | 		.*.ko.cmd \
17 | 		*.mod \
18 | 		.modules.order.cmd \
19 | 		.Module.symvers.cmd
20 | 


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/README.md:
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 1 | # Elastic-TCP: Flexible Congestion Control Algorithm to Adapt for High-BDP Networks
 2 | 
 3 | The paper: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=8642512
 4 | 
 5 | ## Test environment
 6 | * NetEm on receiver side
 7 |   - `qdisc netem 8004: dev ifb0 root refcnt 2 limit 865 delay 100.0ms rate 100Mbit`
 8 | * 100Mbps
 9 | * 100ms RTT
10 | 
11 | Test result:
12 | 
13 | ![image](https://user-images.githubusercontent.com/980728/125387081-eedb0a80-e3cf-11eb-92a1-6f6dfdcce280.png)
14 | 
15 | compared to RENO
16 | 
17 | ![image](https://user-images.githubusercontent.com/980728/130021405-a16e6be4-296d-43d3-b3d9-74635aa5305c.png)
18 | 
19 | compared to CUBIC
20 | 
21 | ![image](https://user-images.githubusercontent.com/980728/130021501-8f97a30b-49a0-43d0-9695-5599ebfa03a4.png)
22 | 
23 | 


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/tcp_elastic.c:
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 1 | #include <linux/module.h>
 2 | #include <net/tcp.h>
 3 | 
 4 | #define ELASTIC_SCALE 6
 5 | #define ELASTIC_UNIT (1 << ELASTIC_SCALE)
 6 | 
 7 | struct elastic {
 8 | 	u32	rtt_max;
 9 | 	u32	rtt_curr;
10 | };
11 | 
12 | static void elastic_init(struct sock *sk)
13 | {
14 | 	struct elastic *ca = inet_csk_ca(sk);
15 | 	ca->rtt_max = 0;
16 | 	ca->rtt_curr = 1;
17 | }
18 | 
19 | static void elastic_cong_avoid(struct sock *sk, u32 ack, u32 acked)
20 | {
21 | 	struct tcp_sock *tp = tcp_sk(sk);
22 | 	struct elastic *ca = inet_csk_ca(sk);
23 | 
24 | 	if (!tcp_is_cwnd_limited(sk))
25 | 		return;
26 | 
27 | 	if (tcp_in_slow_start(tp))
28 | 		tcp_slow_start(tp, acked);
29 | 	else {
30 | 		u64 wwf64 = int_sqrt(tp->snd_cwnd*int_pow(ELASTIC_UNIT,2)*ca->rtt_max/ca->rtt_curr);
31 | 		u32 wwf = wwf64 >> ELASTIC_SCALE;
32 | 		tcp_cong_avoid_ai(tp, tp->snd_cwnd, wwf);
33 | 	}
34 | }
35 | 
36 | static void elastic_update_rtt(struct sock *sk, const struct ack_sample *sample)
37 | {
38 | 	struct elastic *ca = inet_csk_ca(sk);
39 | 	ca->rtt_curr = sample->rtt_us + 1;
40 | 	if (ca->rtt_curr > ca->rtt_max) {
41 | 		ca->rtt_max = ca->rtt_curr;
42 | 	}
43 | }
44 | 
45 | static void elastic_event(struct sock *sk, enum tcp_ca_event event)
46 | {
47 | 	struct elastic *ca = inet_csk_ca(sk);
48 | 	if (event == CA_EVENT_LOSS) {
49 | 		ca->rtt_max = 0;
50 | 	}
51 | }
52 | 
53 | static struct tcp_congestion_ops tcp_elastic __read_mostly = {
54 | 	.name		= "elastic",
55 | 	.owner		= THIS_MODULE,
56 | 	.init		= elastic_init,
57 | 	.ssthresh	= tcp_reno_ssthresh,
58 | 	.undo_cwnd	= tcp_reno_undo_cwnd,
59 | 	.cong_avoid	= elastic_cong_avoid,
60 | 	.pkts_acked	= elastic_update_rtt,
61 | 	.cwnd_event	= elastic_event
62 | };
63 | 
64 | static int __init elastic_register(void)
65 | {
66 | 	BUILD_BUG_ON(sizeof(struct elastic) > ICSK_CA_PRIV_SIZE);
67 | 	return tcp_register_congestion_control(&tcp_elastic);
68 | }
69 | 
70 | static void __exit elastic_unregister(void)
71 | {
72 | 	tcp_unregister_congestion_control(&tcp_elastic);
73 | }
74 | 
75 | module_init(elastic_register);
76 | module_exit(elastic_unregister);
77 | 
78 | MODULE_AUTHOR("xtao<cxxtao@gmail.com>");
79 | MODULE_LICENSE("GPL");
80 | MODULE_DESCRIPTION("Elastic TCP");
81 | 


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