In bbr2sender::adjustnetworkparameters, 1) do not inject a bandwidth sample to max bandwidth filter, and 2) update pacing rate after cwnd is updated. protected by --gfe2_reloadable_flag_quic_bbr2_improve_adjust_network_parameters.
PiperOrigin-RevId: 321198508
Change-Id: I4366a2b159c48302eaf935784dfb7d093d322257
diff --git a/quic/core/congestion_control/bbr2_misc.cc b/quic/core/congestion_control/bbr2_misc.cc
index cdd0cb5..153f63e 100644
--- a/quic/core/congestion_control/bbr2_misc.cc
+++ b/quic/core/congestion_control/bbr2_misc.cc
@@ -213,7 +213,8 @@
void Bbr2NetworkModel::UpdateNetworkParameters(QuicBandwidth bandwidth,
QuicTime::Delta rtt) {
- if (!bandwidth.IsInfinite() && bandwidth > MaxBandwidth()) {
+ if (!improve_adjust_network_parameters_ && !bandwidth.IsInfinite() &&
+ bandwidth > MaxBandwidth()) {
max_bandwidth_filter_.Update(bandwidth);
}
diff --git a/quic/core/congestion_control/bbr2_misc.h b/quic/core/congestion_control/bbr2_misc.h
index cd89e6c..bf22bc5 100644
--- a/quic/core/congestion_control/bbr2_misc.h
+++ b/quic/core/congestion_control/bbr2_misc.h
@@ -446,6 +446,10 @@
float pacing_gain() const { return pacing_gain_; }
void set_pacing_gain(float pacing_gain) { pacing_gain_ = pacing_gain; }
+ bool improve_adjust_network_parameters() const {
+ return improve_adjust_network_parameters_;
+ }
+
private:
const Bbr2Params& Params() const { return *params_; }
const Bbr2Params* const params_;
@@ -477,6 +481,9 @@
float cwnd_gain_;
float pacing_gain_;
+
+ const bool improve_adjust_network_parameters_ =
+ GetQuicReloadableFlag(quic_bbr2_improve_adjust_network_parameters);
};
enum class Bbr2Mode : uint8_t {
diff --git a/quic/core/congestion_control/bbr2_sender.cc b/quic/core/congestion_control/bbr2_sender.cc
index d1b3159..3f80f42 100644
--- a/quic/core/congestion_control/bbr2_sender.cc
+++ b/quic/core/congestion_control/bbr2_sender.cc
@@ -167,14 +167,28 @@
if (mode_ == Bbr2Mode::STARTUP) {
const QuicByteCount prior_cwnd = cwnd_;
- // Normally UpdateCongestionWindow updates |cwnd_| towards the target by a
- // small step per congestion event, by changing |cwnd_| to the bdp at here
- // we are reducing the number of updates needed to arrive at the target.
- cwnd_ = model_.BDP(model_.BandwidthEstimate());
- UpdateCongestionWindow(0);
+ if (model_.improve_adjust_network_parameters()) {
+ QUIC_RELOADABLE_FLAG_COUNT(quic_bbr2_improve_adjust_network_parameters);
+ QuicBandwidth effective_bandwidth =
+ std::max(params.bandwidth, model_.BandwidthEstimate());
+ cwnd_ = cwnd_limits().ApplyLimits(model_.BDP(effective_bandwidth));
+ } else {
+ // Normally UpdateCongestionWindow updates |cwnd_| towards the target by a
+ // small step per congestion event, by changing |cwnd_| to the bdp at here
+ // we are reducing the number of updates needed to arrive at the target.
+ cwnd_ = model_.BDP(model_.BandwidthEstimate());
+ UpdateCongestionWindow(0);
+ }
+
if (!params.allow_cwnd_to_decrease) {
cwnd_ = std::max(cwnd_, prior_cwnd);
}
+
+ if (model_.improve_adjust_network_parameters()) {
+ pacing_rate_ = std::max(
+ pacing_rate_,
+ QuicBandwidth::FromBytesAndTimeDelta(cwnd_, model_.MinRtt()));
+ }
}
}
diff --git a/quic/core/congestion_control/bbr2_simulator_test.cc b/quic/core/congestion_control/bbr2_simulator_test.cc
index 205d356..8ea5217 100644
--- a/quic/core/congestion_control/bbr2_simulator_test.cc
+++ b/quic/core/congestion_control/bbr2_simulator_test.cc
@@ -331,6 +331,10 @@
QuicConnection* sender_connection() { return sender_endpoint_.connection(); }
+ Bbr2Sender::DebugState sender_debug_state() const {
+ return sender_->ExportDebugState();
+ }
+
const QuicConnectionStats& sender_connection_stats() {
return sender_connection()->GetStats();
}
@@ -990,14 +994,46 @@
EXPECT_FALSE(sender_->BandwidthEstimate().IsZero());
}
+TEST_F(Bbr2DefaultTopologyTest, AdjustNetworkParameters) {
+ DefaultTopologyParams params;
+ CreateNetwork(params);
+
+ QUIC_LOG(INFO) << "Initial cwnd: " << sender_debug_state().congestion_window
+ << "\nInitial pacing rate: " << sender_->PacingRate(0)
+ << "\nInitial bandwidth estimate: "
+ << sender_->BandwidthEstimate()
+ << "\nInitial rtt: " << sender_debug_state().min_rtt;
+
+ sender_connection()->AdjustNetworkParameters(
+ SendAlgorithmInterface::NetworkParams(params.BottleneckBandwidth(),
+ params.RTT(),
+ /*allow_cwnd_to_decrease=*/false));
+
+ EXPECT_EQ(params.BDP(), sender_->ExportDebugState().congestion_window);
+
+ if (GetQuicReloadableFlag(quic_bbr2_improve_adjust_network_parameters)) {
+ EXPECT_EQ(params.BottleneckBandwidth(),
+ sender_->PacingRate(/*bytes_in_flight=*/0));
+ EXPECT_NE(params.BottleneckBandwidth(), sender_->BandwidthEstimate());
+ } else {
+ EXPECT_EQ(params.BottleneckBandwidth(), sender_->BandwidthEstimate());
+ }
+
+ EXPECT_APPROX_EQ(params.RTT(), sender_->ExportDebugState().min_rtt, 0.01f);
+
+ DriveOutOfStartup(params);
+}
+
// All Bbr2MultiSenderTests uses the following network topology:
//
// Sender 0 (A Bbr2Sender)
// |
// | <-- local_links[0]
// |
-// | Sender N (1 <= N < kNumLocalLinks) (May or may not be a
-// Bbr2Sender) | | | | <-- local_links[N] | |
+// | Sender N (1 <= N < kNumLocalLinks) (May or may not be a Bbr2Sender)
+// | |
+// | | <-- local_links[N]
+// | |
// Network switch
// * <-- the bottleneck queue in the direction
// | of the receiver
