quiche/recovery/congestion/bbr/
init.rs

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26
27use self::rtt::INITIAL_RTT;
28
29use super::*;
30
31use std::time::Instant;
32
33// BBR Functions at Initialization.
34//
35
36// 4.3.1.  Initialization Steps
37pub fn bbr_init(r: &mut Congestion) {
38    let bbr = &mut r.bbr_state;
39
40    bbr.rtprop = INITIAL_RTT;
41    bbr.rtprop_stamp = Instant::now();
42    bbr.next_round_delivered = r.delivery_rate.delivered();
43
44    r.send_quantum = r.max_datagram_size;
45
46    bbr_init_round_counting(r);
47    bbr_init_full_pipe(r);
48    bbr_init_pacing_rate(r);
49    bbr_enter_startup(r);
50}
51
52// 4.1.1.3.  Tracking Time for the BBR.BtlBw Max Filter
53fn bbr_init_round_counting(r: &mut Congestion) {
54    let bbr = &mut r.bbr_state;
55
56    bbr.next_round_delivered = 0;
57    bbr.round_start = false;
58    bbr.round_count = 0;
59}
60
61// 4.2.1.  Pacing Rate
62fn bbr_init_pacing_rate(r: &mut Congestion) {
63    let bbr = &mut r.bbr_state;
64
65    let srtt = INITIAL_RTT.as_secs_f64();
66
67    // At init, cwnd is initcwnd.
68    let nominal_bandwidth = r.congestion_window as f64 / srtt;
69
70    bbr.pacing_rate = (bbr.pacing_gain * nominal_bandwidth) as u64;
71}
72
73// 4.3.2.1.  Startup Dynamics
74pub fn bbr_enter_startup(r: &mut Congestion) {
75    let bbr = &mut r.bbr_state;
76
77    bbr.state = BBRStateMachine::Startup;
78    bbr.pacing_gain = BBR_HIGH_GAIN;
79    bbr.cwnd_gain = BBR_HIGH_GAIN;
80}
81
82// 4.3.2.2.  Estimating When Startup has Filled the Pipe
83fn bbr_init_full_pipe(r: &mut Congestion) {
84    let bbr = &mut r.bbr_state;
85
86    bbr.filled_pipe = false;
87    bbr.full_bw = 0;
88    bbr.full_bw_count = 0;
89}
quiche/recovery/congestion/bbr/init.rs

quiche/recovery/congestion/bbr/
init.rs
