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Set default for field value "WebRTC-Bwe-ProbingBehavior/min_probe_delta:2ms"

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And add a unit test that verifies that next probe time is set at  is
the expected if the recommended probe size is used.

Bug: webrtc:14392
Change-Id: I239bb3a1c8eefc85509aacc82037c64e3ce49ed7
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/272648
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37901}
This commit is contained in:
Per Kjellander 2022-08-25 10:47:44 +02:00 committed by WebRTC LUCI CQ
parent 263acfeb4b
commit ffd99aa069
4 changed files with 34 additions and 10 deletions
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9
modules/pacing/bitrate_prober.cc
View File

@ -34,7 +34,7 @@ constexpr TimeDelta kProbeClusterTimeout = TimeDelta::Seconds(5);
BitrateProberConfig::BitrateProberConfig(
const FieldTrialsView* key_value_config)
: min_probe_delta("min_probe_delta", TimeDelta::Millis(1)),
: min_probe_delta("min_probe_delta", TimeDelta::Millis(2)),
max_probe_delay("max_probe_delay", TimeDelta::Millis(10)) {
ParseFieldTrial({&min_probe_delta, &max_probe_delay},
key_value_config->Lookup("WebRTC-Bwe-ProbingBehavior"));
@ -107,6 +107,7 @@ void BitrateProber::CreateProbeCluster(
<< cluster.pace_info.send_bitrate_bps << ":"
<< cluster.pace_info.probe_cluster_min_bytes << ":"
<< cluster.pace_info.probe_cluster_min_probes << ")";
// If we are already probing, continue to do so. Otherwise set it to
// kInactive and wait for OnIncomingPacket to start the probing.
if (probing_state_ != ProbingState::kActive)
@ -145,16 +146,13 @@ absl::optional<PacedPacketInfo> BitrateProber::CurrentCluster(Timestamp now) {
return info;
}
// Probe size is recommended based on the probe bitrate required. We choose
// a minimum of twice `kMinProbeDeltaMs` interval to allow scheduling to be
// feasible.
DataSize BitrateProber::RecommendedMinProbeSize() const {
if (clusters_.empty()) {
return DataSize::Zero();
}
DataRate send_rate =
DataRate::BitsPerSec(clusters_.front().pace_info.send_bitrate_bps);
return 2 * send_rate * config_.min_probe_delta;
return send_rate * config_.min_probe_delta;
}
void BitrateProber::ProbeSent(Timestamp now, DataSize size) {
@ -197,6 +195,7 @@ Timestamp BitrateProber::CalculateNextProbeTime(
DataSize sent_bytes = DataSize::Bytes(cluster.sent_bytes);
DataRate send_bitrate =
DataRate::BitsPerSec(cluster.pace_info.send_bitrate_bps);
TimeDelta delta = sent_bytes / send_bitrate;
return cluster.started_at + delta;
}

3
modules/pacing/bitrate_prober.h
View File

@ -66,7 +66,8 @@ class BitrateProber {
absl::optional<PacedPacketInfo> CurrentCluster(Timestamp now);
// Returns the minimum number of bytes that the prober recommends for
// the next probe, or zero if not probing.
// the next probe, or zero if not probing. A probe can consist of multiple
// packets that are sent back to back.
DataSize RecommendedMinProbeSize() const;
// Called to report to the prober that a probe has been sent. In case of

24
modules/pacing/bitrate_prober_unittest.cc
View File

@ -170,6 +170,30 @@ TEST(BitrateProberTest, VerifyProbeSizeOnHighBitrate) {
kHighBitrate * TimeDelta::Millis(1));
}
TEST(BitrateProberTest, ProbeSizeCanBeSetWithFieldTrial) {
const test::ExplicitKeyValueConfig trials(
"WebRTC-Bwe-ProbingBehavior/min_probe_delta:20ms/");
BitrateProber prober(trials);
prober.SetEnabled(true);
const DataRate kHighBitrate = DataRate::KilobitsPerSec(10000); // 10 Mbps
prober.CreateProbeCluster({.at_time = Timestamp::Zero(),
.target_data_rate = kHighBitrate,
.target_duration = TimeDelta::Millis(15),
.target_probe_count = 5,
.id = 0});
EXPECT_EQ(prober.RecommendedMinProbeSize(),
kHighBitrate * TimeDelta::Millis(20));
prober.OnIncomingPacket(DataSize::Bytes(1000));
// Next time to send probe should be "min_probe_delta" if the recommended
// number of bytes has been sent.
prober.ProbeSent(Timestamp::Zero(), prober.RecommendedMinProbeSize());
EXPECT_EQ(prober.NextProbeTime(Timestamp::Zero()),
Timestamp::Zero() + TimeDelta::Millis(20));
}
TEST(BitrateProberTest, MinumumNumberOfProbingPackets) {
const FieldTrialBasedConfig config;
BitrateProber prober(config);

8
modules/pacing/task_queue_paced_sender_unittest.cc
View File

@ -459,9 +459,9 @@ TEST(TaskQueuePacedSenderTest, SchedulesProbeAtSentTime) {
TEST(TaskQueuePacedSenderTest, NoMinSleepTimeWhenProbing) {
// Set min_probe_delta to be less than kMinSleepTime (1ms).
const TimeDelta kMinProbeDelta = TimeDelta::Micros(100);
const TimeDelta kMinProbeDelta = TimeDelta::Micros(200);
ScopedKeyValueConfig trials(
"WebRTC-Bwe-ProbingBehavior/min_probe_delta:100us/");
"WebRTC-Bwe-ProbingBehavior/min_probe_delta:200us/");
GlobalSimulatedTimeController time_controller(Timestamp::Millis(1234));
MockPacketRouter packet_router;
TaskQueuePacedSender pacer(time_controller.GetClock(), &packet_router, trials,
@ -495,7 +495,7 @@ TEST(TaskQueuePacedSenderTest, NoMinSleepTimeWhenProbing) {
// Advance time less than PacingController::kMinSleepTime, probing packets
// for the first millisecond should be sent immediately. Min delta between
// probes is 2x 100us, meaning 4 times per ms we will get least one call to
// probes is 200us, meaning 4 times per ms we will get least one call to
// SendPacket().
DataSize data_sent = DataSize::Zero();
EXPECT_CALL(packet_router,
@ -515,7 +515,7 @@ TEST(TaskQueuePacedSenderTest, NoMinSleepTimeWhenProbing) {
// Verify the amount of probing data sent.
// Probe always starts with a small (1 byte) padding packet that's not
// counted into the probe rate here.
const DataSize kMinProbeSize = 2 * kMinProbeDelta * kProbingRate;
const DataSize kMinProbeSize = kMinProbeDelta * kProbingRate;
EXPECT_EQ(data_sent, DataSize::Bytes(1) + kPacketSize + 4 * kMinProbeSize);
}