In BBRv2 STARTUP, exit after the same number of loss events(2) as PROBE_UP when the B206 connection option is supplied.
Protected by quic_reloadable_flag_quic_bbr2_startup_probe_up_loss_events.
PiperOrigin-RevId: 400785473
diff --git a/quic/core/congestion_control/bbr2_sender.cc b/quic/core/congestion_control/bbr2_sender.cc
index 6938f6d..bddb06a 100644
--- a/quic/core/congestion_control/bbr2_sender.cc
+++ b/quic/core/congestion_control/bbr2_sender.cc
@@ -200,6 +200,12 @@
QUIC_RELOADABLE_FLAG_COUNT(quic_bbr2_ignore_inflight_hi_in_probe_up);
params_.probe_up_ignore_inflight_hi = true;
}
+
+ if (GetQuicReloadableFlag(quic_bbr2_startup_probe_up_loss_events) &&
+ ContainsQuicTag(connection_options, kB206)) {
+ QUIC_RELOADABLE_FLAG_COUNT(quic_bbr2_startup_probe_up_loss_events);
+ params_.startup_full_loss_count = params_.probe_bw_full_loss_count;
+ }
}
Limits<QuicByteCount> Bbr2Sender::GetCwndLimitsByMode() const {
diff --git a/quic/core/congestion_control/bbr2_simulator_test.cc b/quic/core/congestion_control/bbr2_simulator_test.cc
index 9c2cca1..18a9829 100644
--- a/quic/core/congestion_control/bbr2_simulator_test.cc
+++ b/quic/core/congestion_control/bbr2_simulator_test.cc
@@ -463,6 +463,26 @@
EXPECT_APPROX_EQ(params.RTT(), rtt_stats()->min_rtt(), 0.2f);
}
+TEST_F(Bbr2DefaultTopologyTest, SimpleTransferB206) {
+ SetQuicReloadableFlag(quic_bbr2_startup_probe_up_loss_events, true);
+ SetConnectionOption(kB206);
+ DefaultTopologyParams params;
+ CreateNetwork(params);
+
+ // Transfer 12MB.
+ DoSimpleTransfer(12 * 1024 * 1024, QuicTime::Delta::FromSeconds(35));
+ EXPECT_TRUE(Bbr2ModeIsOneOf({Bbr2Mode::PROBE_BW, Bbr2Mode::PROBE_RTT}));
+
+ EXPECT_APPROX_EQ(params.BottleneckBandwidth(),
+ sender_->ExportDebugState().bandwidth_hi, 0.01f);
+
+ EXPECT_LE(sender_loss_rate_in_packets(), 0.05);
+ // The margin here is high, because the aggregation greatly increases
+ // smoothed rtt.
+ EXPECT_GE(params.RTT() * 4, rtt_stats()->smoothed_rtt());
+ EXPECT_APPROX_EQ(params.RTT(), rtt_stats()->min_rtt(), 0.2f);
+}
+
TEST_F(Bbr2DefaultTopologyTest, SimpleTransferBBRB) {
SetQuicReloadableFlag(quic_bbr_use_send_rate_in_max_ack_height_tracker, true);
SetConnectionOption(kBBRB);
diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index 2afa363..ed6bdae 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -165,6 +165,7 @@
// inflight dips below 1.25*BW.
const QuicTag kB203 = TAG('B', '2', '0', '3'); // Ignore inflight_hi until
// PROBE_UP is exited.
+const QuicTag kB206 = TAG('B', '2', '0', '6'); // Exit STARTUP after 2 losses.
const QuicTag kNTLP = TAG('N', 'T', 'L', 'P'); // No tail loss probe
const QuicTag k1TLP = TAG('1', 'T', 'L', 'P'); // 1 tail loss probe
const QuicTag k1RTO = TAG('1', 'R', 'T', 'O'); // Send 1 packet upon RTO
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index 5773ec5..d7e9676 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -119,6 +119,8 @@
QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_match_ietf_reset_code, false)
// When the STMP connection option is sent by the client, timestamps in the QUIC ACK frame are sent and processed.
QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_send_timestamps, false)
+// When the flag is true, exit STARTUP after the same number of loss events as PROBE_UP.
+QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_bbr2_startup_probe_up_loss_events, true)
// When true, QuicDispatcher will silently drop QUIC packets that have invalid flags.
QUIC_FLAG(FLAGS_quic_restart_flag_quic_drop_invalid_flags, true)
// When true, QuicDispatcher will silently drop incoming packets whose UDP source port is on the blocklist.
