For quic loss detection, replace quicconnectionstats.total_loss_detection_time by quicconnectionstats. total_loss_detection_response_time to improve the accuracy of detection speed. protected by existing --gfe2_reloadable_flag_quic_enable_loss_detection_experiment_at_gfe.
On skmobile-cjj5 this reduced the threshold value from 8 to 4.5: http://shortn/_vT0AbUjKU6. shift value did not change.
PiperOrigin-RevId: 317739228
Change-Id: I091fabc50753c754c9377d79f7b5a77878d8fbc8
diff --git a/quic/core/congestion_control/general_loss_algorithm.cc b/quic/core/congestion_control/general_loss_algorithm.cc
index eb0ed77..666e7ea 100644
--- a/quic/core/congestion_control/general_loss_algorithm.cc
+++ b/quic/core/congestion_control/general_loss_algorithm.cc
@@ -12,6 +12,20 @@
namespace quic {
+namespace {
+float DetectionResponseTime(QuicTime::Delta rtt,
+ QuicTime send_time,
+ QuicTime detection_time) {
+ if (detection_time <= send_time || rtt.IsZero()) {
+ // Time skewed, assume a very fast detection where |detection_time| is
+ // |send_time| + |rtt|.
+ return 1.0;
+ }
+ float send_to_detection_us = (detection_time - send_time).ToMicroseconds();
+ return send_to_detection_us / rtt.ToMicroseconds();
+}
+} // namespace
+
GeneralLossAlgorithm::GeneralLossAlgorithm()
: loss_detection_timeout_(QuicTime::Zero()),
reordering_shift_(kDefaultLossDelayShift),
@@ -100,6 +114,8 @@
if (!skip_packet_threshold_detection &&
largest_newly_acked - packet_number >= reordering_threshold_) {
packets_lost->push_back(LostPacket(packet_number, it->bytes_sent));
+ detection_stats.total_loss_detection_response_time +=
+ DetectionResponseTime(max_rtt, it->sent_time, time);
continue;
}
@@ -118,6 +134,8 @@
break;
}
packets_lost->push_back(LostPacket(packet_number, it->bytes_sent));
+ detection_stats.total_loss_detection_response_time +=
+ DetectionResponseTime(max_rtt, it->sent_time, time);
}
if (!least_in_flight_.IsInitialized()) {
// There is no in flight packet.
diff --git a/quic/core/congestion_control/loss_detection_interface.h b/quic/core/congestion_control/loss_detection_interface.h
index d5e0190..6799de9 100644
--- a/quic/core/congestion_control/loss_detection_interface.h
+++ b/quic/core/congestion_control/loss_detection_interface.h
@@ -30,6 +30,9 @@
// Maximum sequence reordering observed in newly acked packets.
QuicPacketCount sent_packets_max_sequence_reordering = 0;
QuicPacketCount sent_packets_num_borderline_time_reorderings = 0;
+ // Total detection response time for lost packets from this detection.
+ // See QuicConnectionStats for the definition of detection response time.
+ float total_loss_detection_response_time = 0.0;
};
// Called when a new ack arrives or the loss alarm fires.
diff --git a/quic/core/congestion_control/uber_loss_algorithm.cc b/quic/core/congestion_control/uber_loss_algorithm.cc
index 243f563..5debad6 100644
--- a/quic/core/congestion_control/uber_loss_algorithm.cc
+++ b/quic/core/congestion_control/uber_loss_algorithm.cc
@@ -56,6 +56,8 @@
stats.sent_packets_max_sequence_reordering);
overall_stats.sent_packets_num_borderline_time_reorderings +=
stats.sent_packets_num_borderline_time_reorderings;
+ overall_stats.total_loss_detection_response_time +=
+ stats.total_loss_detection_response_time;
}
return overall_stats;
diff --git a/quic/core/quic_connection_stats.h b/quic/core/quic_connection_stats.h
index 67220ae..d0211da 100644
--- a/quic/core/quic_connection_stats.h
+++ b/quic/core/quic_connection_stats.h
@@ -47,9 +47,21 @@
QuicPacketCount packets_lost = 0;
QuicPacketCount packet_spuriously_detected_lost = 0;
- // The sum of the detection time of all lost packets. The detection time of a
- // lost packet is defined as: T(detection) - T(send).
- QuicTime::Delta total_loss_detection_time = QuicTime::Delta::Zero();
+ // The sum of loss detection response times of all lost packets, in number of
+ // round trips.
+ // Given a packet detected as lost:
+ // T(S) T(1Rtt) T(D)
+ // |_________________________________|_______|
+ // Where
+ // T(S) is the time when the packet is sent.
+ // T(1Rtt) is one rtt after T(S), using the rtt at the time of detection.
+ // T(D) is the time of detection, i.e. when the packet is declared as lost.
+ // The loss detection response time is defined as
+ // (T(D) - T(S)) / (T(1Rtt) - T(S))
+ //
+ // The average loss detection response time is this number divided by
+ // |packets_lost|. Smaller result means detection is faster.
+ float total_loss_detection_response_time = 0.0;
// Number of times this connection went through the slow start phase.
uint32_t slowstart_count = 0;
diff --git a/quic/core/quic_sent_packet_manager.cc b/quic/core/quic_sent_packet_manager.cc
index 86628ef..4373013 100644
--- a/quic/core/quic_sent_packet_manager.cc
+++ b/quic/core/quic_sent_packet_manager.cc
@@ -978,14 +978,13 @@
stats_->sent_packets_num_borderline_time_reorderings +=
detection_stats.sent_packets_num_borderline_time_reorderings;
+ stats_->total_loss_detection_response_time +=
+ detection_stats.total_loss_detection_response_time;
+
for (const LostPacket& packet : packets_lost_) {
QuicTransmissionInfo* info =
unacked_packets_.GetMutableTransmissionInfo(packet.packet_number);
++stats_->packets_lost;
- if (time > info->sent_time) {
- stats_->total_loss_detection_time =
- stats_->total_loss_detection_time + (time - info->sent_time);
- }
if (debug_delegate_ != nullptr) {
debug_delegate_->OnPacketLoss(packet.packet_number,
info->encryption_level, LOSS_RETRANSMISSION,
diff --git a/quic/core/quic_sent_packet_manager_test.cc b/quic/core/quic_sent_packet_manager_test.cc
index 23aec1e..97d83f5 100644
--- a/quic/core/quic_sent_packet_manager_test.cc
+++ b/quic/core/quic_sent_packet_manager_test.cc
@@ -622,7 +622,7 @@
// know packet 2 is a spurious until it gets acked.
EXPECT_EQ(1u, stats_.packets_spuriously_retransmitted);
EXPECT_EQ(1u, stats_.packets_lost);
- EXPECT_LT(QuicTime::Delta::Zero(), stats_.total_loss_detection_time);
+ EXPECT_LT(0.0, stats_.total_loss_detection_response_time);
EXPECT_LE(1u, stats_.sent_packets_max_sequence_reordering);
}
