gfe-relnote: False deprecate --gfe2_reloadable_flag_quic_bbr_startup_rate_reduction.
Two connection options, BBS4 and BBS5, both protected by this flag, are also deprecated.
PiperOrigin-RevId: 304209090
Change-Id: I101643d1f1aea527f503c3450c6f93b91cfb7750
diff --git a/quic/core/congestion_control/bbr_sender.cc b/quic/core/congestion_control/bbr_sender.cc
index 2961680..ee74d70 100644
--- a/quic/core/congestion_control/bbr_sender.cc
+++ b/quic/core/congestion_control/bbr_sender.cc
@@ -122,8 +122,6 @@
recovery_window_(max_congestion_window_),
slower_startup_(false),
rate_based_startup_(false),
- startup_rate_reduction_multiplier_(0),
- startup_bytes_lost_(0),
enable_ack_aggregation_during_startup_(false),
expire_ack_aggregation_in_startup_(false),
drain_to_target_(false),
@@ -268,20 +266,6 @@
if (config.HasClientRequestedIndependentOption(kBBS1, perspective)) {
rate_based_startup_ = true;
}
- if (GetQuicReloadableFlag(quic_bbr_startup_rate_reduction) &&
- config.HasClientRequestedIndependentOption(kBBS4, perspective)) {
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr_startup_rate_reduction, 1, 2);
- rate_based_startup_ = true;
- // Hits 1.25x pacing multiplier when ~2/3 CWND is lost.
- startup_rate_reduction_multiplier_ = 1;
- }
- if (GetQuicReloadableFlag(quic_bbr_startup_rate_reduction) &&
- config.HasClientRequestedIndependentOption(kBBS5, perspective)) {
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr_startup_rate_reduction, 2, 2);
- rate_based_startup_ = true;
- // Hits 1.25x pacing multiplier when ~1/3 CWND is lost.
- startup_rate_reduction_multiplier_ = 2;
- }
if (GetQuicReloadableFlag(quic_bbr_mitigate_overly_large_bandwidth_sample)) {
if (config.HasClientRequestedIndependentOption(kBWM3, perspective)) {
bytes_lost_multiplier_with_network_parameters_adjusted_ = 3;
@@ -459,9 +443,6 @@
stats_->slowstart_packets_lost += lost_packets.size();
stats_->slowstart_bytes_lost += bytes_lost;
}
- if (startup_rate_reduction_multiplier_ != 0) {
- startup_bytes_lost_ += bytes_lost;
- }
}
excess_acked = sample.extra_acked;
last_packet_send_state = sample.last_packet_send_state;
@@ -851,20 +832,6 @@
return;
}
- // Slow the pacing rate in STARTUP by the bytes_lost / CWND.
- if (startup_rate_reduction_multiplier_ != 0 && has_ever_detected_loss &&
- has_non_app_limited_sample_) {
- pacing_rate_ =
- (1 - (startup_bytes_lost_ * startup_rate_reduction_multiplier_ * 1.0f /
- congestion_window_)) *
- target_rate;
- // Ensure the pacing rate doesn't drop below the startup growth target times
- // the bandwidth estimate.
- pacing_rate_ =
- std::max(pacing_rate_, kStartupGrowthTarget * BandwidthEstimate());
- return;
- }
-
// Do not decrease the pacing rate during startup.
pacing_rate_ = std::max(pacing_rate_, target_rate);
}
diff --git a/quic/core/congestion_control/bbr_sender.h b/quic/core/congestion_control/bbr_sender.h
index 7aa4f69..eb8282a 100644
--- a/quic/core/congestion_control/bbr_sender.h
+++ b/quic/core/congestion_control/bbr_sender.h
@@ -377,11 +377,6 @@
bool slower_startup_;
// When true, disables packet conservation in STARTUP.
bool rate_based_startup_;
- // When non-zero, decreases the rate in STARTUP by the total number of bytes
- // lost in STARTUP divided by CWND.
- uint8_t startup_rate_reduction_multiplier_;
- // Sum of bytes lost in STARTUP.
- QuicByteCount startup_bytes_lost_;
// When true, add the most recent ack aggregation measurement during STARTUP.
bool enable_ack_aggregation_during_startup_;
diff --git a/quic/core/congestion_control/bbr_sender_test.cc b/quic/core/congestion_control/bbr_sender_test.cc
index 483f98b..6f91153 100644
--- a/quic/core/congestion_control/bbr_sender_test.cc
+++ b/quic/core/congestion_control/bbr_sender_test.cc
@@ -1081,108 +1081,6 @@
EXPECT_FALSE(sender_->ExportDebugState().last_sample_is_app_limited);
}
-// Ensures no change in congestion window in STARTUP after loss, but that the
-// rate decreases.
-TEST_F(BbrSenderTest, SimpleTransferStartupRateReduction) {
- SetQuicReloadableFlag(quic_bbr_startup_rate_reduction, true);
- CreateSmallBufferSetup();
-
- SetConnectionOption(kBBS4);
-
- // Run until the full bandwidth is reached and check how many rounds it was.
- bbr_sender_.AddBytesToTransfer(12 * 1024 * 1024);
- bool used_conservation_cwnd = false;
- bool simulator_result = simulator_.RunUntilOrTimeout(
- [this, &used_conservation_cwnd]() {
- if (!sender_->ExportDebugState().is_at_full_bandwidth &&
- sender_->GetCongestionWindow() <
- sender_->ExportDebugState().congestion_window) {
- used_conservation_cwnd = true;
- }
- // Exit once a loss is hit.
- return bbr_sender_.connection()->GetStats().packets_lost > 0 ||
- sender_->ExportDebugState().is_at_full_bandwidth;
- },
- QuicTime::Delta::FromSeconds(5));
- ASSERT_TRUE(simulator_result);
- EXPECT_TRUE(sender_->InRecovery());
- EXPECT_FALSE(used_conservation_cwnd);
- EXPECT_EQ(BbrSender::STARTUP, sender_->ExportDebugState().mode);
- EXPECT_NE(0u, bbr_sender_.connection()->GetStats().packets_lost);
-
- // Lose each outstanding packet and the pacing rate decreases.
- const QuicBandwidth original_pacing_rate = sender_->PacingRate(0);
- QuicBandwidth pacing_rate = original_pacing_rate;
- const QuicByteCount original_cwnd = sender_->GetCongestionWindow();
- LostPacketVector lost_packets;
- lost_packets.push_back(
- LostPacket(QuicPacketNumber(), kMaxOutgoingPacketSize));
- QuicPacketNumber largest_sent =
- bbr_sender_.connection()->sent_packet_manager().GetLargestSentPacket();
- for (QuicPacketNumber packet_number =
- bbr_sender_.connection()->sent_packet_manager().GetLeastUnacked();
- packet_number <= largest_sent; ++packet_number) {
- lost_packets[0].packet_number = packet_number;
- sender_->OnCongestionEvent(false, 0, clock_->Now(), {}, lost_packets);
- EXPECT_EQ(original_cwnd, sender_->GetCongestionWindow());
- EXPECT_GT(original_pacing_rate, sender_->PacingRate(0));
- EXPECT_GE(pacing_rate, sender_->PacingRate(0));
- EXPECT_LE(1.25 * sender_->BandwidthEstimate(), sender_->PacingRate(0));
- pacing_rate = sender_->PacingRate(0);
- }
-}
-
-// Ensures no change in congestion window in STARTUP after loss, but that the
-// rate decreases twice as fast as BBS4.
-TEST_F(BbrSenderTest, SimpleTransferDoubleStartupRateReduction) {
- SetQuicReloadableFlag(quic_bbr_startup_rate_reduction, true);
- CreateSmallBufferSetup();
-
- SetConnectionOption(kBBS5);
-
- // Run until the full bandwidth is reached and check how many rounds it was.
- bbr_sender_.AddBytesToTransfer(12 * 1024 * 1024);
- bool used_conservation_cwnd = false;
- bool simulator_result = simulator_.RunUntilOrTimeout(
- [this, &used_conservation_cwnd]() {
- if (!sender_->ExportDebugState().is_at_full_bandwidth &&
- sender_->GetCongestionWindow() <
- sender_->ExportDebugState().congestion_window) {
- used_conservation_cwnd = true;
- }
- // Exit once a loss is hit.
- return bbr_sender_.connection()->GetStats().packets_lost > 0 ||
- sender_->ExportDebugState().is_at_full_bandwidth;
- },
- QuicTime::Delta::FromSeconds(5));
- ASSERT_TRUE(simulator_result);
- EXPECT_TRUE(sender_->InRecovery());
- EXPECT_FALSE(used_conservation_cwnd);
- EXPECT_EQ(BbrSender::STARTUP, sender_->ExportDebugState().mode);
- EXPECT_NE(0u, bbr_sender_.connection()->GetStats().packets_lost);
-
- // Lose each outstanding packet and the pacing rate decreases.
- const QuicBandwidth original_pacing_rate = sender_->PacingRate(0);
- QuicBandwidth pacing_rate = original_pacing_rate;
- const QuicByteCount original_cwnd = sender_->GetCongestionWindow();
- LostPacketVector lost_packets;
- lost_packets.push_back(
- LostPacket(QuicPacketNumber(), kMaxOutgoingPacketSize));
- QuicPacketNumber largest_sent =
- bbr_sender_.connection()->sent_packet_manager().GetLargestSentPacket();
- for (QuicPacketNumber packet_number =
- bbr_sender_.connection()->sent_packet_manager().GetLeastUnacked();
- packet_number <= largest_sent; ++packet_number) {
- lost_packets[0].packet_number = packet_number;
- sender_->OnCongestionEvent(false, 0, clock_->Now(), {}, lost_packets);
- EXPECT_EQ(original_cwnd, sender_->GetCongestionWindow());
- EXPECT_GT(original_pacing_rate, sender_->PacingRate(0));
- EXPECT_GE(pacing_rate, sender_->PacingRate(0));
- EXPECT_LE(1.25 * sender_->BandwidthEstimate(), sender_->PacingRate(0));
- pacing_rate = sender_->PacingRate(0);
- }
-}
-
TEST_F(BbrSenderTest, DerivedPacingGainStartup) {
CreateDefaultSetup();
diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index b9ddae9..8e03bb3 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -88,10 +88,8 @@
// conservation in BBR STARTUP
const QuicTag kBBS3 = TAG('B', 'B', 'S', '3'); // Slowstart packet
// conservation in BBR STARTUP
-const QuicTag kBBS4 = TAG('B', 'B', 'S', '4'); // Reduce rate in STARTUP by
- // bytes_lost / CWND.
-const QuicTag kBBS5 = TAG('B', 'B', 'S', '5'); // Reduce rate in STARTUP by
- // 2 * bytes_lost / CWND.
+const QuicTag kBBS4 = TAG('B', 'B', 'S', '4'); // DEPRECATED
+const QuicTag kBBS5 = TAG('B', 'B', 'S', '5'); // DEPRECATED
const QuicTag kBBRR = TAG('B', 'B', 'R', 'R'); // Rate-based recovery in BBR
const QuicTag kBBR1 = TAG('B', 'B', 'R', '1'); // DEPRECATED
const QuicTag kBBR2 = TAG('B', 'B', 'R', '2'); // DEPRECATED
