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Allow probing up to 2x allocation limit

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The limit we put on probing is a bit too conservative now. If an
allocation limit is set, this CL allows probing up to 2x the current
max allocation limit.

This better handles overshooting when networks actually have the
capacity to allow bursts.

Bug: webrtc:10070
Change-Id: I0003f6b22512c13b6a83c1934952a2c3a2b70b48
Reviewed-on: https://webrtc-review.googlesource.com/c/112905
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25888}
This commit is contained in:
Erik Språng
2018-12-03 18:43:50 +01:00
committed by Commit Bot
parent 9cccf85314
commit 74fb822b67
2 changed files with 19 additions and 14 deletions
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8
modules/congestion_controller/goog_cc/probe_controller.cc
View File

@ -336,8 +336,14 @@ std::vector<ProbeClusterConfig> ProbeController::InitiateProbing(
max_bitrate_bps_ > 0 ? max_bitrate_bps_ : kDefaultMaxProbingBitrateBps;
if (limit_probes_with_allocateable_rate_ &&
max_total_allocated_bitrate_ > 0) {
// If a max allocated bitrate has been configured, allow probing up to 2x
// that rate. This allows some overhead to account for bursty streams,
// which otherwise would have to ramp up when the overshoot is already in
// progress.
// It also avoids minor quality reduction caused by probes often being
// received at slightly less than the target probe bitrate.
max_probe_bitrate_bps =
std::min(max_probe_bitrate_bps, max_total_allocated_bitrate_);
std::min(max_probe_bitrate_bps, max_total_allocated_bitrate_ * 2);
}
if (bitrate > max_probe_bitrate_bps) {
bitrate = max_probe_bitrate_bps;

25
modules/congestion_controller/goog_cc/probe_controller_unittest.cc
View File

@ -265,37 +265,36 @@ TEST_F(ProbeControllerTest, TestExponentialProbingOverflow) {
TEST_F(ProbeControllerTest, TestAllocatedBitrateCap) {
const int64_t kMbpsMultiplier = 1000000;
const int64_t kMaxBitrateBps = 100 * kMbpsMultiplier;
auto probes = probe_controller_->SetBitrates(
kMinBitrateBps, 10 * kMbpsMultiplier, 100 * kMbpsMultiplier, NowMs());
kMinBitrateBps, 10 * kMbpsMultiplier, kMaxBitrateBps, NowMs());
// Configure ALR for periodic probing.
probe_controller_->EnablePeriodicAlrProbing(true);
int64_t alr_start_time = clock_.TimeInMilliseconds();
probe_controller_->SetAlrStartTimeMs(alr_start_time);
// Verify that probe bitrate is capped at the specified max bitrate.
int64_t estimated_bitrate_bps = kMaxBitrateBps / 10;
probes =
probe_controller_->SetEstimatedBitrate(60 * kMbpsMultiplier, NowMs());
EXPECT_EQ(probes[0].target_data_rate.bps(), 100 * kMbpsMultiplier);
probe_controller_->SetEstimatedBitrate(estimated_bitrate_bps, NowMs());
// Set a max allocated bitrate below the current max.
probes = probe_controller_->OnMaxTotalAllocatedBitrate(1 * kMbpsMultiplier,
NowMs());
// Set a max allocated bitrate below the current estimate.
int64_t max_allocated_bps = estimated_bitrate_bps - 1 * kMbpsMultiplier;
probes =
probe_controller_->OnMaxTotalAllocatedBitrate(max_allocated_bps, NowMs());
EXPECT_TRUE(probes.empty()); // No probe since lower than current max.
// Other probes, such as ALR, such also be capped at the same limit.
// Probes such as ALR capped at 2x the max allocation limit.
clock_.AdvanceTimeMilliseconds(5000);
probes = probe_controller_->Process(NowMs());
EXPECT_EQ(probes[0].target_data_rate.bps(), 1 * kMbpsMultiplier);
EXPECT_EQ(probes[0].target_data_rate.bps(), 2 * max_allocated_bps);
// Advance time and configure remove allocated bitrate limit.
// Remove allocation limit.
EXPECT_TRUE(
probe_controller_->OnMaxTotalAllocatedBitrate(0, NowMs()).empty());
// New ALR probes use previous limits.
clock_.AdvanceTimeMilliseconds(5000);
probes = probe_controller_->Process(NowMs());
EXPECT_EQ(probes[0].target_data_rate.bps(), 100 * kMbpsMultiplier);
EXPECT_EQ(probes[0].target_data_rate.bps(), estimated_bitrate_bps * 2);
}
} // namespace test