| OLD | NEW |
|---|
| (Empty) |
| 1 // Copyright (c) 2015 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "net/quic/congestion_control/tcp_cubic_sender_bytes.h" | |
| 6 | |
| 7 #include <algorithm> | |
| 8 | |
| 9 #include "net/quic/congestion_control/prr_sender.h" | |
| 10 #include "net/quic/congestion_control/rtt_stats.h" | |
| 11 #include "net/quic/crypto/crypto_protocol.h" | |
| 12 #include "net/quic/proto/cached_network_parameters.pb.h" | |
| 13 #include "net/quic/quic_bug_tracker.h" | |
| 14 #include "net/quic/quic_flags.h" | |
| 15 | |
| 16 using std::max; | |
| 17 using std::min; | |
| 18 | |
| 19 namespace net { | |
| 20 | |
| 21 namespace { | |
| 22 // Constants based on TCP defaults. | |
| 23 // The minimum cwnd based on RFC 3782 (TCP NewReno) for cwnd reductions on a | |
| 24 // fast retransmission. | |
| 25 const QuicByteCount kDefaultMinimumCongestionWindow = 2 * kDefaultTCPMSS; | |
| 26 } // namespace | |
| 27 | |
| 28 TcpCubicSenderBytes::TcpCubicSenderBytes( | |
| 29 const QuicClock* clock, | |
| 30 const RttStats* rtt_stats, | |
| 31 bool reno, | |
| 32 QuicPacketCount initial_tcp_congestion_window, | |
| 33 QuicPacketCount max_congestion_window, | |
| 34 QuicConnectionStats* stats) | |
| 35 : TcpCubicSenderBase(clock, rtt_stats, reno, stats), | |
| 36 cubic_(clock), | |
| 37 num_acked_packets_(0), | |
| 38 congestion_window_(initial_tcp_congestion_window * kDefaultTCPMSS), | |
| 39 min_congestion_window_(kDefaultMinimumCongestionWindow), | |
| 40 max_congestion_window_(max_congestion_window * kDefaultTCPMSS), | |
| 41 slowstart_threshold_(max_congestion_window * kDefaultTCPMSS), | |
| 42 initial_tcp_congestion_window_(initial_tcp_congestion_window * | |
| 43 kDefaultTCPMSS), | |
| 44 initial_max_tcp_congestion_window_(max_congestion_window * | |
| 45 kDefaultTCPMSS), | |
| 46 min_slow_start_exit_window_(min_congestion_window_) {} | |
| 47 | |
| 48 TcpCubicSenderBytes::~TcpCubicSenderBytes() {} | |
| 49 | |
| 50 void TcpCubicSenderBytes::SetCongestionWindowFromBandwidthAndRtt( | |
| 51 QuicBandwidth bandwidth, | |
| 52 QuicTime::Delta rtt) { | |
| 53 QuicByteCount new_congestion_window = bandwidth.ToBytesPerPeriod(rtt); | |
| 54 if (FLAGS_quic_no_lower_bw_resumption_limit) { | |
| 55 // Limit new CWND if needed. | |
| 56 congestion_window_ = | |
| 57 max(min_congestion_window_, | |
| 58 min(new_congestion_window, | |
| 59 kMaxResumptionCongestionWindow * kDefaultTCPMSS)); | |
| 60 } else { | |
| 61 congestion_window_ = | |
| 62 max(min(new_congestion_window, | |
| 63 kMaxResumptionCongestionWindow * kDefaultTCPMSS), | |
| 64 kMinCongestionWindowForBandwidthResumption * kDefaultTCPMSS); | |
| 65 } | |
| 66 } | |
| 67 | |
| 68 void TcpCubicSenderBytes::SetCongestionWindowInPackets( | |
| 69 QuicPacketCount congestion_window) { | |
| 70 congestion_window_ = congestion_window * kDefaultTCPMSS; | |
| 71 } | |
| 72 | |
| 73 void TcpCubicSenderBytes::SetMinCongestionWindowInPackets( | |
| 74 QuicPacketCount congestion_window) { | |
| 75 min_congestion_window_ = congestion_window * kDefaultTCPMSS; | |
| 76 } | |
| 77 | |
| 78 void TcpCubicSenderBytes::SetNumEmulatedConnections(int num_connections) { | |
| 79 TcpCubicSenderBase::SetNumEmulatedConnections(num_connections); | |
| 80 cubic_.SetNumConnections(num_connections_); | |
| 81 } | |
| 82 | |
| 83 void TcpCubicSenderBytes::ExitSlowstart() { | |
| 84 slowstart_threshold_ = congestion_window_; | |
| 85 } | |
| 86 | |
| 87 void TcpCubicSenderBytes::OnPacketLost(QuicPacketNumber packet_number, | |
| 88 QuicByteCount lost_bytes, | |
| 89 QuicByteCount bytes_in_flight) { | |
| 90 // TCP NewReno (RFC6582) says that once a loss occurs, any losses in packets | |
| 91 // already sent should be treated as a single loss event, since it's expected. | |
| 92 if (packet_number <= largest_sent_at_last_cutback_) { | |
| 93 if (last_cutback_exited_slowstart_) { | |
| 94 ++stats_->slowstart_packets_lost; | |
| 95 stats_->slowstart_bytes_lost += lost_bytes; | |
| 96 if (slow_start_large_reduction_) { | |
| 97 // Reduce congestion window by lost_bytes for every loss. | |
| 98 congestion_window_ = | |
| 99 max(congestion_window_ - lost_bytes, min_slow_start_exit_window_); | |
| 100 slowstart_threshold_ = congestion_window_; | |
| 101 } | |
| 102 } | |
| 103 DVLOG(1) << "Ignoring loss for largest_missing:" << packet_number | |
| 104 << " because it was sent prior to the last CWND cutback."; | |
| 105 return; | |
| 106 } | |
| 107 ++stats_->tcp_loss_events; | |
| 108 last_cutback_exited_slowstart_ = InSlowStart(); | |
| 109 if (InSlowStart()) { | |
| 110 ++stats_->slowstart_packets_lost; | |
| 111 } | |
| 112 | |
| 113 if (!no_prr_) { | |
| 114 prr_.OnPacketLost(bytes_in_flight); | |
| 115 } | |
| 116 | |
| 117 // TODO(jri): Separate out all of slow start into a separate class. | |
| 118 if (slow_start_large_reduction_ && InSlowStart()) { | |
| 119 DCHECK_LT(kDefaultTCPMSS, congestion_window_); | |
| 120 if (congestion_window_ >= 2 * initial_tcp_congestion_window_) { | |
| 121 min_slow_start_exit_window_ = congestion_window_ / 2; | |
| 122 } | |
| 123 congestion_window_ = congestion_window_ - kDefaultTCPMSS; | |
| 124 } else if (reno_) { | |
| 125 congestion_window_ = congestion_window_ * RenoBeta(); | |
| 126 } else { | |
| 127 congestion_window_ = | |
| 128 cubic_.CongestionWindowAfterPacketLoss(congestion_window_); | |
| 129 } | |
| 130 if (congestion_window_ < min_congestion_window_) { | |
| 131 congestion_window_ = min_congestion_window_; | |
| 132 } | |
| 133 slowstart_threshold_ = congestion_window_; | |
| 134 largest_sent_at_last_cutback_ = largest_sent_packet_number_; | |
| 135 // Reset packet count from congestion avoidance mode. We start counting again | |
| 136 // when we're out of recovery. | |
| 137 num_acked_packets_ = 0; | |
| 138 DVLOG(1) << "Incoming loss; congestion window: " << congestion_window_ | |
| 139 << " slowstart threshold: " << slowstart_threshold_; | |
| 140 } | |
| 141 | |
| 142 QuicByteCount TcpCubicSenderBytes::GetCongestionWindow() const { | |
| 143 return congestion_window_; | |
| 144 } | |
| 145 | |
| 146 QuicByteCount TcpCubicSenderBytes::GetSlowStartThreshold() const { | |
| 147 return slowstart_threshold_; | |
| 148 } | |
| 149 | |
| 150 // Called when we receive an ack. Normal TCP tracks how many packets one ack | |
| 151 // represents, but quic has a separate ack for each packet. | |
| 152 void TcpCubicSenderBytes::MaybeIncreaseCwnd( | |
| 153 QuicPacketNumber acked_packet_number, | |
| 154 QuicByteCount acked_bytes, | |
| 155 QuicByteCount bytes_in_flight) { | |
| 156 QUIC_BUG_IF(InRecovery()) << "Never increase the CWND during recovery."; | |
| 157 // Do not increase the congestion window unless the sender is close to using | |
| 158 // the current window. | |
| 159 if (!IsCwndLimited(bytes_in_flight)) { | |
| 160 cubic_.OnApplicationLimited(); | |
| 161 return; | |
| 162 } | |
| 163 if (congestion_window_ >= max_congestion_window_) { | |
| 164 return; | |
| 165 } | |
| 166 if (InSlowStart()) { | |
| 167 // TCP slow start, exponential growth, increase by one for each ACK. | |
| 168 congestion_window_ += kDefaultTCPMSS; | |
| 169 DVLOG(1) << "Slow start; congestion window: " << congestion_window_ | |
| 170 << " slowstart threshold: " << slowstart_threshold_; | |
| 171 return; | |
| 172 } | |
| 173 // Congestion avoidance. | |
| 174 if (reno_) { | |
| 175 // Classic Reno congestion avoidance. | |
| 176 ++num_acked_packets_; | |
| 177 // Divide by num_connections to smoothly increase the CWND at a faster rate | |
| 178 // than conventional Reno. | |
| 179 if (num_acked_packets_ * num_connections_ >= | |
| 180 congestion_window_ / kDefaultTCPMSS) { | |
| 181 congestion_window_ += kDefaultTCPMSS; | |
| 182 num_acked_packets_ = 0; | |
| 183 } | |
| 184 | |
| 185 DVLOG(1) << "Reno; congestion window: " << congestion_window_ | |
| 186 << " slowstart threshold: " << slowstart_threshold_ | |
| 187 << " congestion window count: " << num_acked_packets_; | |
| 188 } else { | |
| 189 congestion_window_ = | |
| 190 min(max_congestion_window_, | |
| 191 cubic_.CongestionWindowAfterAck(acked_bytes, congestion_window_, | |
| 192 rtt_stats_->min_rtt())); | |
| 193 DVLOG(1) << "Cubic; congestion window: " << congestion_window_ | |
| 194 << " slowstart threshold: " << slowstart_threshold_; | |
| 195 } | |
| 196 } | |
| 197 | |
| 198 void TcpCubicSenderBytes::HandleRetransmissionTimeout() { | |
| 199 cubic_.Reset(); | |
| 200 slowstart_threshold_ = congestion_window_ / 2; | |
| 201 congestion_window_ = min_congestion_window_; | |
| 202 } | |
| 203 | |
| 204 void TcpCubicSenderBytes::OnConnectionMigration() { | |
| 205 TcpCubicSenderBase::OnConnectionMigration(); | |
| 206 cubic_.Reset(); | |
| 207 num_acked_packets_ = 0; | |
| 208 congestion_window_ = initial_tcp_congestion_window_; | |
| 209 max_congestion_window_ = initial_max_tcp_congestion_window_; | |
| 210 slowstart_threshold_ = initial_max_tcp_congestion_window_; | |
| 211 } | |
| 212 | |
| 213 CongestionControlType TcpCubicSenderBytes::GetCongestionControlType() const { | |
| 214 return reno_ ? kRenoBytes : kCubicBytes; | |
| 215 } | |
| 216 | |
| 217 } // namespace net | |
| OLD | NEW |
|---|
Chromium Code Reviews
Issue 2193073003:
Move shared files in net/quic/ into net/quic/core/ (Closed)
Base URL: https://chromium.googlesource.com/chromium/src.git@master