gfe-relnote: (n/a) Remove unused QUIC connection option "BBQ4". Not protected.
Also changed kDerivedHighCWNDGain to 2.0f and fixed test 'DerivedCWNDGainStartup'.
PiperOrigin-RevId: 247060931
Change-Id: Ie1253736d8bc4dd81ba700ef0ee7826bba5eeb69
diff --git a/quic/core/congestion_control/bbr_sender.cc b/quic/core/congestion_control/bbr_sender.cc
index 3ca2063..2c0ad34 100644
--- a/quic/core/congestion_control/bbr_sender.cc
+++ b/quic/core/congestion_control/bbr_sender.cc
@@ -30,7 +30,7 @@
// The newly derived gain for STARTUP, equal to 4 * ln(2)
const float kDerivedHighGain = 2.773f;
// The newly derived CWND gain for STARTUP, 2.
-const float kDerivedHighCWNDGain = 2.773f;
+const float kDerivedHighCWNDGain = 2.0f;
// The gain used in STARTUP after loss has been detected.
// 1.5 is enough to allow for 25% exogenous loss and still observe a 25% growth
// in measured bandwidth.
@@ -329,11 +329,6 @@
QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr_slower_startup3, 3, 4);
enable_ack_aggregation_during_startup_ = true;
}
- if (GetQuicReloadableFlag(quic_bbr_slower_startup3) &&
- config.HasClientRequestedIndependentOption(kBBQ4, perspective)) {
- QUIC_RELOADABLE_FLAG_COUNT_N(quic_bbr_slower_startup3, 4, 4);
- set_drain_gain(kModerateProbeRttMultiplier);
- }
if (GetQuicReloadableFlag(quic_bbr_slower_startup4) &&
config.HasClientRequestedIndependentOption(kBBQ5, perspective)) {
QUIC_RELOADABLE_FLAG_COUNT(quic_bbr_slower_startup4);
diff --git a/quic/core/congestion_control/bbr_sender.h b/quic/core/congestion_control/bbr_sender.h
index d01dbfe..843764b 100644
--- a/quic/core/congestion_control/bbr_sender.h
+++ b/quic/core/congestion_control/bbr_sender.h
@@ -164,6 +164,10 @@
drain_gain_ = drain_gain;
}
+ // Returns the current estimate of the RTT of the connection. Outside of the
+ // edge cases, this is minimum RTT.
+ QuicTime::Delta GetMinRtt() const;
+
DebugState ExportDebugState() const;
private:
@@ -179,9 +183,6 @@
QuicRoundTripCount>
MaxAckHeightFilter;
- // Returns the current estimate of the RTT of the connection. Outside of the
- // edge cases, this is minimum RTT.
- QuicTime::Delta GetMinRtt() const;
// Returns whether the connection has achieved full bandwidth required to exit
// the slow start.
bool IsAtFullBandwidth() const;
diff --git a/quic/core/congestion_control/bbr_sender_test.cc b/quic/core/congestion_control/bbr_sender_test.cc
index 21675e6..1f4c082 100644
--- a/quic/core/congestion_control/bbr_sender_test.cc
+++ b/quic/core/congestion_control/bbr_sender_test.cc
@@ -11,6 +11,7 @@
#include "net/third_party/quiche/src/quic/core/congestion_control/rtt_stats.h"
#include "net/third_party/quiche/src/quic/core/quic_packets.h"
#include "net/third_party/quiche/src/quic/core/quic_utils.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_flags.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_logging.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_ptr_util.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_test.h"
@@ -304,7 +305,7 @@
// The margin here is quite high, since there exists a possibility that the
// connection just exited high gain cycle.
- EXPECT_APPROX_EQ(kTestRtt, rtt_stats_->smoothed_rtt(), 0.2f);
+ EXPECT_APPROX_EQ(kTestRtt, sender_->GetMinRtt(), 0.2f);
}
TEST_F(BbrSenderTest, SimpleTransferEarlyPacketLoss) {
@@ -471,6 +472,20 @@
EXPECT_LE(loss_rate, 0.31);
}
+// Test the number of losses incurred by the startup phase in a situation when
+// the buffer is less than BDP, with a STARTUP CWND gain of 2.
+TEST_F(BbrSenderTest, PacketLossOnSmallBufferStartupDerivedCWNDGain) {
+ SetQuicReloadableFlag(quic_bbr_slower_startup3, true);
+ CreateSmallBufferSetup();
+
+ SetConnectionOption(kBBQ2);
+ DriveOutOfStartup();
+ float loss_rate =
+ static_cast<float>(bbr_sender_.connection()->GetStats().packets_lost) /
+ bbr_sender_.connection()->GetStats().packets_sent;
+ EXPECT_LE(loss_rate, 0.1);
+}
+
// Ensures the code transitions loss recovery states correctly (NOT_IN_RECOVERY
// -> CONSERVATION -> GROWTH -> NOT_IN_RECOVERY).
TEST_F(BbrSenderTest, RecoveryStates) {
@@ -602,15 +617,14 @@
EXPECT_APPROX_EQ(kTestRtt, rtt_stats_->smoothed_rtt(), 0.1f);
}
+// TODO(wub): Re-enable this test once default drain_gain changed to 0.75.
// Verify that the DRAIN phase works correctly.
-TEST_F(BbrSenderTest, ShallowDrain) {
+TEST_F(BbrSenderTest, DISABLED_ShallowDrain) {
SetQuicReloadableFlag(quic_bbr_slower_startup3, true);
// Disable Ack Decimation on the receiver, because it can increase srtt.
QuicConnectionPeer::SetAckMode(receiver_.connection(), AckMode::TCP_ACKING);
CreateDefaultSetup();
- // BBQ4 increases the pacing gain in DRAIN to 0.75
- SetConnectionOption(kBBQ4);
const QuicTime::Delta timeout = QuicTime::Delta::FromSeconds(10);
// Get the queue at the bottleneck, which is the outgoing queue at the port to
// which the receiver is connected.
@@ -1186,7 +1200,7 @@
TEST_F(BbrSenderTest, DerivedCWNDGainStartup) {
SetQuicReloadableFlag(quic_bbr_slower_startup3, true);
- CreateDefaultSetup();
+ CreateSmallBufferSetup();
SetConnectionOption(kBBQ2);
EXPECT_EQ(3u, sender_->num_startup_rtts());
@@ -1208,7 +1222,10 @@
EXPECT_EQ(3u, sender_->ExportDebugState().rounds_without_bandwidth_gain);
EXPECT_APPROX_EQ(kTestLinkBandwidth,
sender_->ExportDebugState().max_bandwidth, 0.01f);
- EXPECT_EQ(0u, bbr_sender_.connection()->GetStats().packets_lost);
+ float loss_rate =
+ static_cast<float>(bbr_sender_.connection()->GetStats().packets_lost) /
+ bbr_sender_.connection()->GetStats().packets_sent;
+ EXPECT_LT(loss_rate, 0.15f);
EXPECT_FALSE(sender_->ExportDebugState().last_sample_is_app_limited);
// Expect an SRTT less than 2.7 * Min RTT on exit from STARTUP.
EXPECT_GT(kTestRtt * 2.7, rtt_stats_->smoothed_rtt());
diff --git a/quic/core/crypto/crypto_protocol.h b/quic/core/crypto/crypto_protocol.h
index 5b65267..6873e0f 100644
--- a/quic/core/crypto/crypto_protocol.h
+++ b/quic/core/crypto/crypto_protocol.h
@@ -26,6 +26,9 @@
typedef std::string ServerConfigID;
+// The following tags have been deprecated and should not be reused:
+// "BBQ4"
+
// clang-format off
const QuicTag kCHLO = TAG('C', 'H', 'L', 'O'); // Client hello
const QuicTag kSHLO = TAG('S', 'H', 'L', 'O'); // Server hello
@@ -112,7 +115,6 @@
// CWND gain.
const QuicTag kBBQ3 = TAG('B', 'B', 'Q', '3'); // BBR with ack aggregation
// compensation in STARTUP.
-const QuicTag kBBQ4 = TAG('B', 'B', 'Q', '4'); // Drain gain of 0.75.
const QuicTag kBBQ5 = TAG('B', 'B', 'Q', '5'); // Expire ack aggregation upon
// bandwidth increase in
// STARTUP.
