Deprecate FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 in the disabled position because it neve…

net/quic/core/congestion_control/bbr_sender_test.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/congestion_control/bbr_sender.h"
 
 #include <algorithm>
 #include <map>
 #include <memory>
 
@@ skipping 273 matching lines @@
 
   DoSimpleTransfer(12 * 1024 * 1024, QuicTime::Delta::FromSeconds(30));
   EXPECT_EQ(BbrSender::PROBE_BW, sender_->ExportDebugState().mode);
   ExpectApproxEq(kTestLinkBandwidth, sender_->ExportDebugState().max_bandwidth,
                  0.01f);
   EXPECT_GE(bbr_sender_.connection()->GetStats().packets_lost, 0u);
   EXPECT_FALSE(sender_->ExportDebugState().last_sample_is_app_limited);
 }
 
 // Test a simple long data transfer with 2 rtts of aggregation.
-TEST_F(BbrSenderTest, SimpleTransfer2RTTAggregation) {
-  QuicFlagSaver flags;
-  FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 = true;
-  FLAGS_quic_reloadable_flag_quic_bbr_add_tso_cwnd = false;
-  CreateDefaultSetup();
-  // 2 RTTs of aggregation, with a max of 10kb.
-  EnableAggregation(10 * 1024, 2 * kTestRtt);
-
-  // Transfer 12MB.
-  DoSimpleTransfer(12 * 1024 * 1024, QuicTime::Delta::FromSeconds(35));
-  EXPECT_EQ(BbrSender::PROBE_BW, sender_->ExportDebugState().mode);
-  // It's possible to read a bandwidth as much as 50% too high with aggregation.
-  EXPECT_LE(kTestLinkBandwidth * 0.99f,
-            sender_->ExportDebugState().max_bandwidth);
-  // TODO(ianswett): Tighten this bound once we understand why BBR is
-  // overestimating bandwidth with aggregation. b/36022633
-  EXPECT_GE(kTestLinkBandwidth * 1.5f,
-            sender_->ExportDebugState().max_bandwidth);
-  // TODO(ianswett): Expect 0 packets are lost once BBR no longer measures
-  // bandwidth higher than the link rate.
-  // The margin here is high, because the aggregation greatly increases
-  // smoothed rtt.
-  EXPECT_GE(kTestRtt * 4, rtt_stats_->smoothed_rtt());
-  ExpectApproxEq(kTestRtt, rtt_stats_->min_rtt(), 0.1f);
-}
-
-// Test a simple long data transfer with 2 rtts of aggregation.
 TEST_F(BbrSenderTest, SimpleTransfer2RTTAggregationBytes) {
-  FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 = false;
   FLAGS_quic_reloadable_flag_quic_bbr_ack_aggregation_bytes = true;
   FLAGS_quic_reloadable_flag_quic_bbr_add_tso_cwnd = false;
   CreateDefaultSetup();
   // 2 RTTs of aggregation, with a max of 10kb.
   EnableAggregation(10 * 1024, 2 * kTestRtt);
 
   // Transfer 12MB.
   DoSimpleTransfer(12 * 1024 * 1024, QuicTime::Delta::FromSeconds(35));
   EXPECT_EQ(BbrSender::PROBE_BW, sender_->ExportDebugState().mode);
   // It's possible to read a bandwidth as much as 50% too high with aggregation.
   EXPECT_LE(kTestLinkBandwidth * 0.99f,
             sender_->ExportDebugState().max_bandwidth);
   // TODO(ianswett): Tighten this bound once we understand why BBR is
   // overestimating bandwidth with aggregation. b/36022633
   EXPECT_GE(kTestLinkBandwidth * 1.5f,
             sender_->ExportDebugState().max_bandwidth);
   // TODO(ianswett): Expect 0 packets are lost once BBR no longer measures
   // bandwidth higher than the link rate.
   EXPECT_FALSE(sender_->ExportDebugState().last_sample_is_app_limited);
   // The margin here is high, because the aggregation greatly increases
   // smoothed rtt.
   EXPECT_GE(kTestRtt * 4, rtt_stats_->smoothed_rtt());
   ExpectApproxEq(kTestRtt, rtt_stats_->min_rtt(), 0.1f);
 }
 
 TEST_F(BbrSenderTest, SimpleTransfer2RTTAggregationKeepSending) {
-  FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 = false;
   FLAGS_quic_reloadable_flag_quic_bbr_ack_aggregation_bytes = false;
   FLAGS_quic_reloadable_flag_quic_bbr_add_tso_cwnd = false;
   FLAGS_quic_reloadable_flag_quic_bbr_keep_sending_at_recent_rate = true;
   CreateDefaultSetup();
   // 2 RTTs of aggregation, with a max of 10kb.
   EnableAggregation(10 * 1024, 2 * kTestRtt);
 
   // Transfer 12MB.
   DoSimpleTransfer(12 * 1024 * 1024, QuicTime::Delta::FromSeconds(35));
   EXPECT_EQ(BbrSender::PROBE_BW, sender_->ExportDebugState().mode);
   // It's possible to read a bandwidth as much as 50% too high with aggregation.
   EXPECT_LE(kTestLinkBandwidth * 0.95f,
             sender_->ExportDebugState().max_bandwidth);
   // TODO(ianswett): Tighten this bound once we understand why BBR is
   // overestimating bandwidth with aggregation. b/36022633
   EXPECT_GE(kTestLinkBandwidth * 1.5f,
             sender_->ExportDebugState().max_bandwidth);
   // TODO(ianswett): Expect 0 packets are lost once BBR no longer measures
   // bandwidth higher than the link rate.
   EXPECT_FALSE(sender_->ExportDebugState().last_sample_is_app_limited);
   // The margin here is high, because the aggregation greatly increases
   // smoothed rtt.
   EXPECT_GE(kTestRtt * 4, rtt_stats_->smoothed_rtt());
   ExpectApproxEq(kTestRtt, rtt_stats_->min_rtt(), 0.1f);
 }
 
 // Test a simple long data transfer with 2 rtts of aggregation.
 TEST_F(BbrSenderTest, SimpleTransferAckDecimation) {
-  FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 = false;
   FLAGS_quic_reloadable_flag_quic_bbr_ack_aggregation_bytes = true;
   // Decrease the CWND gain so extra CWND is required with stretch acks.
   base::SetFlag(&FLAGS_quic_bbr_cwnd_gain, 1.0);
   sender_ = new BbrSender(
       rtt_stats_,
       QuicSentPacketManagerPeer::GetUnackedPacketMap(
           QuicConnectionPeer::GetSentPacketManager(bbr_sender_.connection())),
       kInitialCongestionWindowPackets, kDefaultMaxCongestionWindowPackets,
       &random_);
   QuicConnectionPeer::SetSendAlgorithm(bbr_sender_.connection(), sender_);
@@ skipping 15 matching lines @@
   // TODO(ianswett): Expect 0 packets are lost once BBR no longer measures
   // bandwidth higher than the link rate.
   EXPECT_FALSE(sender_->ExportDebugState().last_sample_is_app_limited);
   // The margin here is high, because the aggregation greatly increases
   // smoothed rtt.
   EXPECT_GE(kTestRtt * 2, rtt_stats_->smoothed_rtt());
   ExpectApproxEq(kTestRtt, rtt_stats_->min_rtt(), 0.1f);
 }
 
 TEST_F(BbrSenderTest, SimpleTransferAckDecimationKeepSending) {
-  FLAGS_quic_reloadable_flag_quic_bbr_ack_spacing2 = false;
   FLAGS_quic_reloadable_flag_quic_bbr_ack_aggregation_bytes = false;
   FLAGS_quic_reloadable_flag_quic_bbr_keep_sending_at_recent_rate = true;
   // Decrease the CWND gain so extra CWND is required with stretch acks.
   base::SetFlag(&FLAGS_quic_bbr_cwnd_gain, 1.0);
   sender_ = new BbrSender(
       rtt_stats_,
       QuicSentPacketManagerPeer::GetUnackedPacketMap(
           QuicConnectionPeer::GetSentPacketManager(bbr_sender_.connection())),
       kInitialCongestionWindowPackets, kDefaultMaxCongestionWindowPackets,
       &random_);
@@ skipping 366 matching lines @@
   sender_->ResumeConnectionState(params, false);
   EXPECT_EQ(kTestLinkBandwidth, sender_->ExportDebugState().max_bandwidth);
   EXPECT_EQ(kTestLinkBandwidth, sender_->BandwidthEstimate());
   ExpectApproxEq(kTestRtt, sender_->ExportDebugState().min_rtt, 0.01f);
 
   DriveOutOfStartup();
 }
 
 }  // namespace test
 }  // namespace net