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Reland "Stop exponential probing if 2xmax allocated bitrate lower than BWE."

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This reverts commit 802dd5bdbd97d880761059c7362c9e843211e32d.

First patch set is pure reland.
New patch set adds field trial flag.


Original change's description:
Stop exponential probing if 2xmax allocated bitrate lower than BWE.
 
Without this, if max allocated bitrate is lowered while exponential probing is ongoing, a new probe can be sent at a rate of the new low max allocated bitrate which may cause BWE to decrease.

Bug: webrtc:14928
Change-Id: I35c341bbaced800d9931657d62c73a17a3279b7c
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/344440
Auto-Submit: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Diep Bui <diepbp@webrtc.org>
Commit-Queue: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41965}
This commit is contained in:
Per K 2024-03-25 15:57:00 +01:00 committed by WebRTC LUCI CQ
parent 6f1d4e74cc
commit 08848ea04c
3 changed files with 58 additions and 14 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
modules/congestion_controller/goog_cc/probe_controller.cc
View File

@ -88,6 +88,7 @@ ProbeControllerConfig::ProbeControllerConfig(
second_exponential_probe_scale("p2", 6.0),
further_exponential_probe_scale("step_size", 2),
further_probe_threshold("further_probe_threshold", 0.7),
abort_further_probe_if_max_lower_than_current("abort_further", false),
alr_probing_interval("alr_interval", TimeDelta::Seconds(5)),
alr_probe_scale("alr_scale", 2),
network_state_estimate_probing_interval("network_state_interval",
@ -112,19 +113,27 @@ ProbeControllerConfig::ProbeControllerConfig(
skip_if_estimate_larger_than_fraction_of_max(
"skip_if_est_larger_than_fraction_of_max",
0.0) {
ParseFieldTrial(
{&first_exponential_probe_scale, &second_exponential_probe_scale,
&further_exponential_probe_scale, &further_probe_threshold,
&alr_probing_interval, &alr_probe_scale,
&probe_on_max_allocated_bitrate_change, &first_allocation_probe_scale,
&second_allocation_probe_scale, &allocation_probe_limit_by_current_scale,
&min_probe_duration, &network_state_estimate_probing_interval,
&probe_if_estimate_lower_than_network_state_estimate_ratio,
&estimate_lower_than_network_state_estimate_probing_interval,
&network_state_probe_scale, &network_state_probe_duration,
&min_probe_packets_sent, &loss_limited_probe_scale,
&skip_if_estimate_larger_than_fraction_of_max},
key_value_config->Lookup("WebRTC-Bwe-ProbingConfiguration"));
ParseFieldTrial({&first_exponential_probe_scale,
&second_exponential_probe_scale,
&further_exponential_probe_scale,
&further_probe_threshold,
&abort_further_probe_if_max_lower_than_current,
&alr_probing_interval,
&alr_probe_scale,
&probe_on_max_allocated_bitrate_change,
&first_allocation_probe_scale,
&second_allocation_probe_scale,
&allocation_probe_limit_by_current_scale,
&min_probe_duration,
&network_state_estimate_probing_interval,
&probe_if_estimate_lower_than_network_state_estimate_ratio,
&estimate_lower_than_network_state_estimate_probing_interval,
&network_state_probe_scale,
&network_state_probe_duration,
&min_probe_packets_sent,
&loss_limited_probe_scale,
&skip_if_estimate_larger_than_fraction_of_max},
key_value_config->Lookup("WebRTC-Bwe-ProbingConfiguration"));
// Specialized keys overriding subsets of WebRTC-Bwe-ProbingConfiguration
ParseFieldTrial(
@ -294,7 +303,14 @@ std::vector<ProbeClusterConfig> ProbeController::SetEstimatedBitrate(
if (state_ == State::kWaitingForProbingResult) {
// Continue probing if probing results indicate channel has greater
// capacity.
// capacity unless we already reached the needed bitrate.
if (config_.abort_further_probe_if_max_lower_than_current &&
(bitrate > max_bitrate_ ||
(!max_total_allocated_bitrate_.IsZero() &&
bitrate > 2 * max_total_allocated_bitrate_))) {
// No need to continue probing.
min_bitrate_to_probe_further_ = DataRate::PlusInfinity();
}
DataRate network_state_estimate_probe_further_limit =
config_.network_state_estimate_probing_interval->IsFinite() &&
network_estimate_

1
modules/congestion_controller/goog_cc/probe_controller.h
View File

@ -42,6 +42,7 @@ struct ProbeControllerConfig {
FieldTrialOptional<double> second_exponential_probe_scale;
FieldTrialParameter<double> further_exponential_probe_scale;
FieldTrialParameter<double> further_probe_threshold;
FieldTrialParameter<bool> abort_further_probe_if_max_lower_than_current;
// Configures how often we send ALR probes and how big they are.
FieldTrialParameter<TimeDelta> alr_probing_interval;

27
modules/congestion_controller/goog_cc/probe_controller_unittest.cc
View File

@ -23,8 +23,10 @@
#include "test/gmock.h"
#include "test/gtest.h"
using ::testing::Gt;
using ::testing::IsEmpty;
using ::testing::NiceMock;
using ::testing::SizeIs;
namespace webrtc {
namespace test {
@ -325,6 +327,31 @@ TEST(ProbeControllerTest, TestExponentialProbing) {
EXPECT_EQ(probes[0].target_data_rate.bps(), 2 * 1800);
}
TEST(ProbeControllerTest, ExponentialProbingStopIfMaxAllocatedBitrateLow) {
ProbeControllerFixture fixture(
"WebRTC-Bwe-ProbingConfiguration/abort_further:true/");
std::unique_ptr<ProbeController> probe_controller =
fixture.CreateController();
ASSERT_THAT(
probe_controller->OnNetworkAvailability({.network_available = true}),
IsEmpty());
auto probes = probe_controller->SetBitrates(
kMinBitrate, kStartBitrate, kMaxBitrate, fixture.CurrentTime());
ASSERT_THAT(probes, SizeIs(Gt(0)));
// Repeated probe normally is sent when estimated bitrate climbs above
// 0.7 * 6 * kStartBitrate = 1260. But since allocated bitrate i slow, expect
// exponential probing to stop.
probes = probe_controller->OnMaxTotalAllocatedBitrate(kStartBitrate,
fixture.CurrentTime());
EXPECT_THAT(probes, IsEmpty());
probes = probe_controller->SetEstimatedBitrate(
DataRate::BitsPerSec(1800), BandwidthLimitedCause::kDelayBasedLimited,
fixture.CurrentTime());
EXPECT_THAT(probes, IsEmpty());
}
TEST(ProbeControllerTest, TestExponentialProbingTimeout) {
ProbeControllerFixture fixture;
std::unique_ptr<ProbeController> probe_controller =