quiche/recovery/congestion/bbr/
init.rs

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26
27use super::*;
28
29use std::time::Instant;
30
31// BBR Functions at Initialization.
32//
33
34// 4.3.1.  Initialization Steps
35pub fn bbr_init(r: &mut Congestion) {
36    let bbr = &mut r.bbr_state;
37
38    bbr.rtprop = r.initial_rtt;
39    bbr.rtprop_stamp = Instant::now();
40    bbr.next_round_delivered = r.delivery_rate.delivered();
41
42    r.send_quantum = r.max_datagram_size;
43
44    bbr_init_round_counting(r);
45    bbr_init_full_pipe(r);
46    bbr_init_pacing_rate(r);
47    bbr_enter_startup(r);
48}
49
50// 4.1.1.3.  Tracking Time for the BBR.BtlBw Max Filter
51fn bbr_init_round_counting(r: &mut Congestion) {
52    let bbr = &mut r.bbr_state;
53
54    bbr.next_round_delivered = 0;
55    bbr.round_start = false;
56    bbr.round_count = 0;
57}
58
59// 4.2.1.  Pacing Rate
60fn bbr_init_pacing_rate(r: &mut Congestion) {
61    let bbr = &mut r.bbr_state;
62
63    let srtt = r.initial_rtt.as_secs_f64();
64
65    // At init, cwnd is initcwnd.
66    let nominal_bandwidth = r.congestion_window as f64 / srtt;
67
68    bbr.pacing_rate = (bbr.pacing_gain * nominal_bandwidth) as u64;
69}
70
71// 4.3.2.1.  Startup Dynamics
72pub fn bbr_enter_startup(r: &mut Congestion) {
73    let bbr = &mut r.bbr_state;
74
75    bbr.state = BBRStateMachine::Startup;
76    bbr.pacing_gain = BBR_HIGH_GAIN;
77    bbr.cwnd_gain = BBR_HIGH_GAIN;
78}
79
80// 4.3.2.2.  Estimating When Startup has Filled the Pipe
81fn bbr_init_full_pipe(r: &mut Congestion) {
82    let bbr = &mut r.bbr_state;
83
84    bbr.filled_pipe = false;
85    bbr.full_bw = 0;
86    bbr.full_bw_count = 0;
87}
quiche/recovery/congestion/bbr/init.rs

quiche/recovery/congestion/bbr/
init.rs
