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Efficient Metric Recorder

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Computing all metrics using constant extra memory.
PlotHistogram methods are executed in constant time.
-- Previously throughput and delay were using O(num_packets) extra memory and their associated PlotHistograms took linear time complexity.

Added MetricRecorder unittests

R=stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1257683006 .

Cr-Commit-Position: refs/heads/master@{#9658}
This commit is contained in:
Cesar Magalhaes
2015-07-30 11:22:05 +02:00
parent 028cf48828
commit e2cb1f12c3
5 changed files with 269 additions and 156 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
webrtc/modules/modules.gyp
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@ -224,6 +224,7 @@
'remote_bitrate_estimator/remote_bitrate_estimator_unittest_helper.h',
'remote_bitrate_estimator/test/bwe_test_framework_unittest.cc',
'remote_bitrate_estimator/test/bwe_unittest.cc',
'remote_bitrate_estimator/test/metric_recorder_unittest.cc',
'remote_bitrate_estimator/test/estimators/nada_unittest.cc',
'rtp_rtcp/source/mock/mock_rtp_payload_strategy.h',
'rtp_rtcp/source/byte_io_unittest.cc',

277
webrtc/modules/remote_bitrate_estimator/test/metric_recorder.cc
View File

@ -17,73 +17,14 @@ namespace testing {
namespace bwe {
namespace {
template <typename T>
T Sum(const std::vector<T>& input) {
T total = 0;
for (T val : input) {
total += val;
}
return total;
}
template <typename T>
double Average(const std::vector<T>& array, size_t size) {
return static_cast<double>(Sum(array)) / size;
}
template <typename T>
std::vector<T> Abs(const std::vector<T>& input) {
std::vector<T> output(input);
for (T val : output) {
val = std::abs(val);
}
return output;
}
template <typename T>
std::vector<double> Pow(const std::vector<T>& input, double p) {
std::vector<double> output;
for (T val : input) {
output.push_back(pow(static_cast<double>(val), p));
}
return output;
}
template <typename T>
double StandardDeviation(const std::vector<T>& array, size_t size) {
double mean = Average(array, size);
std::vector<double> square_values = Pow(array, 2.0);
double var = Average(square_values, size) - mean * mean;
return sqrt(var);
}
// Holder mean, Manhattan distance for p=1, EuclidianNorm/sqrt(n) for p=2.
template <typename T>
double NormLp(const std::vector<T>& array, size_t size, double p) {
std::vector<T> abs_values = Abs(array);
std::vector<double> pow_values = Pow(abs_values, p);
return pow(Sum(pow_values) / size, 1.0 / p);
double NormLp(T sum, size_t size, double p) {
return pow(sum / size, 1.0 / p);
}
}
template <typename T>
std::vector<T> PositiveFilter(const std::vector<T>& input) {
std::vector<T> output(input);
for (T val : output) {
val = val > 0 ? val : 0;
}
return output;
}
template <typename T>
std::vector<T> NegativeFilter(const std::vector<T>& input) {
std::vector<T> output(input);
for (T val : output) {
val = val < 0 ? -val : 0;
}
return output;
}
} // namespace
const double kP = 1.0; // Used for Norm Lp.
LinkShare::LinkShare(ChokeFilter* choke_filter)
: choke_filter_(choke_filter), running_flows_(choke_filter->flow_ids()) {
@ -119,14 +60,17 @@ MetricRecorder::MetricRecorder(const std::string algorithm_name,
packet_sender_(packet_sender),
link_share_(link_share),
now_ms_(0),
delays_ms_(),
throughput_bytes_(),
weighted_estimate_error_(),
sum_delays_ms_(0),
delay_histogram_ms_(),
sum_delays_square_ms2_(0),
sum_throughput_bytes_(0),
last_unweighted_estimate_error_(0),
optimal_throughput_bits_(0),
last_available_bitrate_per_flow_kbps_(0),
start_computing_metrics_ms_(0),
started_computing_metrics_(false) {
started_computing_metrics_(false),
num_packets_received_(0) {
std::fill_n(sum_lp_weighted_estimate_error_, 2, 0);
}
void MetricRecorder::SetPlotInformation(
@ -224,27 +168,48 @@ void MetricRecorder::UpdateObjective() {
}
uint32_t MetricRecorder::GetTotalAvailableKbps() {
if (link_share_ == nullptr)
return 0;
return link_share_->TotalAvailableKbps();
}
uint32_t MetricRecorder::GetAvailablePerFlowKbps() {
if (link_share_ == nullptr)
return 0;
return link_share_->AvailablePerFlowKbps(flow_id_);
}
uint32_t MetricRecorder::GetSendingEstimateKbps() {
if (packet_sender_ == nullptr)
return 0;
return packet_sender_->TargetBitrateKbps();
}
void MetricRecorder::PushDelayMs(int64_t delay_ms, int64_t arrival_time_ms) {
if (ShouldRecord(arrival_time_ms)) {
delays_ms_.push_back(delay_ms);
sum_delays_ms_ += delay_ms;
sum_delays_square_ms2_ += delay_ms * delay_ms;
if (delay_histogram_ms_.find(delay_ms) == delay_histogram_ms_.end()) {
delay_histogram_ms_[delay_ms] = 0;
}
++delay_histogram_ms_[delay_ms];
}
}
void MetricRecorder::UpdateEstimateError(int64_t new_value) {
int64_t lp_value = pow(static_cast<double>(std::abs(new_value)), kP);
if (new_value < 0) {
sum_lp_weighted_estimate_error_[0] += lp_value;
} else {
sum_lp_weighted_estimate_error_[1] += lp_value;
}
}
void MetricRecorder::PushThroughputBytes(size_t payload_size,
int64_t arrival_time_ms) {
if (ShouldRecord(arrival_time_ms)) {
throughput_bytes_.push_back(payload_size);
++num_packets_received_;
sum_throughput_bytes_ += payload_size;
int64_t current_available_per_flow_kbps =
static_cast<int64_t>(GetAvailablePerFlowKbps());
@ -253,10 +218,12 @@ void MetricRecorder::PushThroughputBytes(size_t payload_size,
static_cast<int64_t>(GetSendingEstimateKbps()) -
current_available_per_flow_kbps;
weighted_estimate_error_.push_back(
((current_bitrate_diff_kbps + last_unweighted_estimate_error_) *
(arrival_time_ms - plot_information_[kThroughput].time_ms)) /
2);
int64_t weighted_estimate_error =
(((current_bitrate_diff_kbps + last_unweighted_estimate_error_) *
(arrival_time_ms - plot_information_[kThroughput].time_ms)) /
2);
UpdateEstimateError(weighted_estimate_error);
optimal_throughput_bits_ +=
((current_available_per_flow_kbps +
@ -281,56 +248,21 @@ bool MetricRecorder::ShouldRecord(int64_t arrival_time_ms) {
}
}
// The weighted_estimate_error_ was weighted based on time windows.
// This function scales back the result before plotting.
double MetricRecorder::Renormalize(double x) {
size_t num_packets_received = delays_ms_.size();
return (x * num_packets_received) / now_ms_;
}
void MetricRecorder::PlotThroughputHistogram(
const std::string& title,
const std::string& bwe_name,
size_t num_flows,
int64_t extra_offset_ms,
const std::string optimum_id) const {
double optimal_bitrate_per_flow_kbps = static_cast<double>(
optimal_throughput_bits_ / RunDurationMs(extra_offset_ms));
inline double U(int64_t x, double alpha) {
if (alpha == 1.0) {
return log(static_cast<double>(x));
}
return pow(static_cast<double>(x), 1.0 - alpha) / (1.0 - alpha);
}
double neg_error = Renormalize(
NormLp(sum_lp_weighted_estimate_error_[0], num_packets_received_, kP));
double pos_error = Renormalize(
NormLp(sum_lp_weighted_estimate_error_[1], num_packets_received_, kP));
inline double U(size_t x, double alpha) {
return U(static_cast<int64_t>(x), alpha);
}
// TODO(magalhaesc): Update ObjectiveFunction.
double MetricRecorder::ObjectiveFunction() {
const double kDelta = 0.15; // Delay penalty factor.
const double kAlpha = 1.0;
const double kBeta = 1.0;
double throughput_metric = U(Sum(throughput_bytes_), kAlpha);
double delay_penalty = kDelta * U(Sum(delays_ms_), kBeta);
return throughput_metric - delay_penalty;
}
void MetricRecorder::PlotThroughputHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
int64_t extra_offset_ms,
const std::string optimum_id) {
size_t num_packets_received = delays_ms_.size();
int64_t duration_ms = now_ms_ - start_computing_metrics_ms_ - extra_offset_ms;
double average_bitrate_kbps =
static_cast<double>(8 * Sum(throughput_bytes_) / duration_ms);
double optimal_bitrate_per_flow_kbps =
static_cast<double>(optimal_throughput_bits_ / duration_ms);
std::vector<int64_t> positive = PositiveFilter(weighted_estimate_error_);
std::vector<int64_t> negative = NegativeFilter(weighted_estimate_error_);
double p_error = Renormalize(NormLp(positive, num_packets_received, 1.0));
double n_error = Renormalize(NormLp(negative, num_packets_received, 1.0));
double average_bitrate_kbps = AverageBitrateKbps(extra_offset_ms);
// Prevent the error to be too close to zero (plotting issue).
double extra_error = average_bitrate_kbps / 500;
@ -341,8 +273,8 @@ void MetricRecorder::PlotThroughputHistogram(const std::string& title,
BWE_TEST_LOGGING_LABEL(4, title, "average_bitrate_(kbps)", num_flows);
BWE_TEST_LOGGING_LIMITERRORBAR(
4, bwe_name, average_bitrate_kbps,
average_bitrate_kbps - n_error - extra_error,
average_bitrate_kbps + p_error + extra_error, "estimate_error",
average_bitrate_kbps - neg_error - extra_error,
average_bitrate_kbps + pos_error + extra_error, "estimate_error",
optimal_bitrate_per_flow_kbps, optimum_title, flow_id_);
BWE_TEST_LOGGING_LOG1("RESULTS >>> " + bwe_name + " Channel utilization : ",
@ -350,8 +282,8 @@ void MetricRecorder::PlotThroughputHistogram(const std::string& title,
100.0 * static_cast<double>(average_bitrate_kbps) /
optimal_bitrate_per_flow_kbps);
RTC_UNUSED(p_error);
RTC_UNUSED(n_error);
RTC_UNUSED(pos_error);
RTC_UNUSED(neg_error);
RTC_UNUSED(extra_error);
RTC_UNUSED(optimal_bitrate_per_flow_kbps);
}
@ -359,32 +291,22 @@ void MetricRecorder::PlotThroughputHistogram(const std::string& title,
void MetricRecorder::PlotThroughputHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
int64_t extra_offset_ms) {
int64_t extra_offset_ms) const {
PlotThroughputHistogram(title, bwe_name, num_flows, extra_offset_ms, "");
}
void MetricRecorder::PlotDelayHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
int64_t one_way_path_delay_ms) {
size_t num_packets_received = delays_ms_.size();
double average_delay_ms = Average(delays_ms_, num_packets_received);
int64_t one_way_path_delay_ms) const {
double average_delay_ms =
static_cast<double>(sum_delays_ms_) / num_packets_received_;
// Prevent the error to be too close to zero (plotting issue).
double extra_error = average_delay_ms / 500;
double tenth_sigma_ms =
StandardDeviation(delays_ms_, num_packets_received) / 10.0 + extra_error;
size_t per_5_index = (num_packets_received - 1) / 20;
std::nth_element(delays_ms_.begin(), delays_ms_.begin() + per_5_index,
delays_ms_.end());
int64_t percentile_5_ms = delays_ms_[per_5_index];
size_t per_95_index = num_packets_received - 1 - per_5_index;
std::nth_element(delays_ms_.begin(), delays_ms_.begin() + per_95_index,
delays_ms_.end());
int64_t percentile_95_ms = delays_ms_[per_95_index];
double tenth_sigma_ms = DelayStdDev() / 10.0 + extra_error;
int64_t percentile_5_ms = NthDelayPercentile(5);
int64_t percentile_95_ms = NthDelayPercentile(95);
BWE_TEST_LOGGING_LABEL(5, title, "average_delay_(ms)", num_flows)
BWE_TEST_LOGGING_ERRORBAR(5, bwe_name, average_delay_ms, percentile_5_ms,
@ -407,7 +329,7 @@ void MetricRecorder::PlotDelayHistogram(const std::string& title,
void MetricRecorder::PlotLossHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
float global_loss_ratio) {
float global_loss_ratio) const {
BWE_TEST_LOGGING_LABEL(6, title, "packet_loss_ratio_(%)", num_flows)
BWE_TEST_LOGGING_BAR(6, bwe_name, 100.0f * global_loss_ratio, flow_id_);
@ -417,7 +339,7 @@ void MetricRecorder::PlotLossHistogram(const std::string& title,
void MetricRecorder::PlotObjectiveHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows) {
size_t num_flows) const {
BWE_TEST_LOGGING_LABEL(7, title, "objective_function", num_flows)
BWE_TEST_LOGGING_BAR(7, bwe_name, ObjectiveFunction(), flow_id_);
}
@ -444,6 +366,73 @@ void MetricRecorder::ResumeFlow(int64_t paused_time_ms) {
link_share_->ResumeFlow(flow_id_);
}
double MetricRecorder::AverageBitrateKbps(int64_t extra_offset_ms) const {
int64_t duration_ms = RunDurationMs(extra_offset_ms);
if (duration_ms == 0)
return 0.0;
return static_cast<double>(8 * sum_throughput_bytes_ / duration_ms);
}
int64_t MetricRecorder::RunDurationMs(int64_t extra_offset_ms) const {
return now_ms_ - start_computing_metrics_ms_ - extra_offset_ms;
}
double MetricRecorder::DelayStdDev() const {
if (num_packets_received_ == 0) {
return 0.0;
}
double mean = static_cast<double>(sum_delays_ms_) / num_packets_received_;
double mean2 =
static_cast<double>(sum_delays_square_ms2_) / num_packets_received_;
return sqrt(mean2 - pow(mean, 2.0));
}
// Since delay values are bounded in a subset of [0, 5000] ms,
// this function's execution time is O(1), independend of num_packets_received_.
int64_t MetricRecorder::NthDelayPercentile(int n) const {
if (num_packets_received_ == 0) {
return 0;
}
size_t num_packets_remaining = (n * num_packets_received_) / 100;
for (auto hist : delay_histogram_ms_) {
if (num_packets_remaining <= hist.second)
return static_cast<int64_t>(hist.first);
num_packets_remaining -= hist.second;
}
assert(false);
return -1;
}
// The weighted_estimate_error_ was weighted based on time windows.
// This function scales back the result before plotting.
double MetricRecorder::Renormalize(double x) const {
return (x * num_packets_received_) / now_ms_;
}
inline double U(int64_t x, double alpha) {
if (alpha == 1.0) {
return log(static_cast<double>(x));
}
return pow(static_cast<double>(x), 1.0 - alpha) / (1.0 - alpha);
}
inline double U(size_t x, double alpha) {
return U(static_cast<int64_t>(x), alpha);
}
// TODO(magalhaesc): Update ObjectiveFunction.
double MetricRecorder::ObjectiveFunction() const {
const double kDelta = 0.15; // Delay penalty factor.
const double kAlpha = 1.0;
const double kBeta = 1.0;
double throughput_metric = U(sum_throughput_bytes_, kAlpha);
double delay_penalty = kDelta * U(sum_delays_ms_, kBeta);
return throughput_metric - delay_penalty;
}
} // namespace bwe
} // namespace testing
} // namespace webrtc

38
webrtc/modules/remote_bitrate_estimator/test/metric_recorder.h
View File

@ -16,6 +16,7 @@
#include <vector>
#include "webrtc/base/common.h"
#include "webrtc/test/testsupport/gtest_prod_util.h"
#include "webrtc/modules/remote_bitrate_estimator/test/packet_sender.h"
namespace webrtc {
@ -88,26 +89,26 @@ class MetricRecorder {
const std::string& bwe_name,
size_t num_flows,
int64_t extra_offset_ms,
const std::string optimum_id);
const std::string optimum_id) const;
void PlotThroughputHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
int64_t extra_offset_ms);
int64_t extra_offset_ms) const;
void PlotDelayHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
int64_t one_way_path_delay_ms);
int64_t one_way_path_delay_ms) const;
void PlotLossHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows,
float global_loss_ratio);
float global_loss_ratio) const;
void PlotObjectiveHistogram(const std::string& title,
const std::string& bwe_name,
size_t num_flows);
size_t num_flows) const;
void set_start_computing_metrics_ms(int64_t start_computing_metrics_ms) {
start_computing_metrics_ms_ = start_computing_metrics_ms;
@ -122,17 +123,27 @@ class MetricRecorder {
void PlotZero();
private:
FRIEND_TEST_ALL_PREFIXES(MetricRecorderTest, NoPackets);
FRIEND_TEST_ALL_PREFIXES(MetricRecorderTest, RegularPackets);
FRIEND_TEST_ALL_PREFIXES(MetricRecorderTest, VariableDelayPackets);
uint32_t GetTotalAvailableKbps();
uint32_t GetAvailablePerFlowKbps();
uint32_t GetSendingEstimateKbps();
double ObjectiveFunction();
double ObjectiveFunction() const;
double Renormalize(double x);
double Renormalize(double x) const;
bool ShouldRecord(int64_t arrival_time_ms);
void PushDelayMs(int64_t delay_ms, int64_t arrival_time_ms);
void PushThroughputBytes(size_t throughput_bytes, int64_t arrival_time_ms);
void UpdateEstimateError(int64_t new_value);
double DelayStdDev() const;
int64_t NthDelayPercentile(int n) const;
double AverageBitrateKbps(int64_t extra_offset_ms) const;
int64_t RunDurationMs(int64_t extra_offset_ms) const;
enum Metrics {
kThroughput = 0,
kDelay,
@ -152,15 +163,20 @@ class MetricRecorder {
PlotInformation plot_information_[kNumMetrics];
std::vector<int64_t> delays_ms_;
std::vector<size_t> throughput_bytes_;
// (Receiving rate - available bitrate per flow) * time window.
std::vector<int64_t> weighted_estimate_error_;
int64_t sum_delays_ms_;
// delay_histogram_ms_[i] counts how many packets have delay = i ms.
std::map<int64_t, size_t> delay_histogram_ms_;
int64_t sum_delays_square_ms2_; // Used to compute standard deviation.
size_t sum_throughput_bytes_;
// ((Receiving rate - available bitrate per flow) * time window)^p.
// 0 for negative values, 1 for positive values.
int64_t sum_lp_weighted_estimate_error_[2];
int64_t last_unweighted_estimate_error_;
int64_t optimal_throughput_bits_;
int64_t last_available_bitrate_per_flow_kbps_;
int64_t start_computing_metrics_ms_;
bool started_computing_metrics_;
size_t num_packets_received_;
};
} // namespace bwe

107
webrtc/modules/remote_bitrate_estimator/test/metric_recorder_unittest.cc Normal file
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@ -0,0 +1,107 @@
/*
* Copyright (c) 2015 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/modules/remote_bitrate_estimator/test/metric_recorder.h"
#include <algorithm>
#include <vector>
#include "testing/gtest/include/gtest/gtest.h"
namespace webrtc {
namespace testing {
namespace bwe {
class MetricRecorderTest : public ::testing::Test {
public:
MetricRecorderTest() : metric_recorder_("Test", 0, nullptr, nullptr) {}
~MetricRecorderTest() {}
protected:
MetricRecorder metric_recorder_;
};
TEST_F(MetricRecorderTest, NoPackets) {
EXPECT_EQ(metric_recorder_.AverageBitrateKbps(0), 0);
EXPECT_EQ(metric_recorder_.DelayStdDev(), 0.0);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(0), 0);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(5), 0);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(95), 0);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(100), 0);
}
TEST_F(MetricRecorderTest, RegularPackets) {
const size_t kPayloadSizeBytes = 1200;
const int64_t kDelayMs = 20;
const int64_t kInterpacketGapMs = 5;
const int kNumPackets = 1000;
for (int i = 0; i < kNumPackets; ++i) {
int64_t arrival_time_ms = kInterpacketGapMs * i + kDelayMs;
metric_recorder_.UpdateTime(arrival_time_ms);
metric_recorder_.PushDelayMs(kDelayMs, arrival_time_ms);
metric_recorder_.PushThroughputBytes(kPayloadSizeBytes, arrival_time_ms);
}
EXPECT_NEAR(
metric_recorder_.AverageBitrateKbps(0),
static_cast<uint32_t>(kPayloadSizeBytes * 8) / (kInterpacketGapMs), 10);
EXPECT_EQ(metric_recorder_.DelayStdDev(), 0.0);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(0), kDelayMs);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(5), kDelayMs);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(95), kDelayMs);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(100), kDelayMs);
}
TEST_F(MetricRecorderTest, VariableDelayPackets) {
const size_t kPayloadSizeBytes = 1200;
const int64_t kInterpacketGapMs = 2000;
const int kNumPackets = 1000;
std::vector<int64_t> delays_ms;
for (int i = 0; i < kNumPackets; ++i) {
delays_ms.push_back(static_cast<int64_t>(i + 1));
}
// Order of packets should not matter here.
std::random_shuffle(delays_ms.begin(), delays_ms.end());
int first_received_ms = delays_ms[0];
int64_t last_received_ms = 0;
for (int i = 0; i < kNumPackets; ++i) {
int64_t arrival_time_ms = kInterpacketGapMs * i + delays_ms[i];
last_received_ms = std::max(last_received_ms, arrival_time_ms);
metric_recorder_.UpdateTime(arrival_time_ms);
metric_recorder_.PushDelayMs(delays_ms[i], arrival_time_ms);
metric_recorder_.PushThroughputBytes(kPayloadSizeBytes, arrival_time_ms);
}
size_t received_bits = kPayloadSizeBytes * 8 * kNumPackets;
EXPECT_NEAR(metric_recorder_.AverageBitrateKbps(0),
static_cast<uint32_t>(received_bits) /
((last_received_ms - first_received_ms)),
10);
double expected_x = (kNumPackets + 1) / 2.0;
double expected_x2 = ((kNumPackets + 1) * (2 * kNumPackets + 1)) / 6.0;
double var = expected_x2 - pow(expected_x, 2.0);
EXPECT_NEAR(metric_recorder_.DelayStdDev(), sqrt(var), kNumPackets / 1000.0);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(0), 1);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(5), (5 * kNumPackets) / 100);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(95), (95 * kNumPackets) / 100);
EXPECT_EQ(metric_recorder_.NthDelayPercentile(100), kNumPackets);
}
} // namespace bwe
} // namespace testing
} // namespace webrtc

2
webrtc/modules/remote_bitrate_estimator/test/plot_bars.sh
View File

@ -111,7 +111,7 @@ function gen_gnuplot_bar_input {
# Scale all latency plots with the same vertical scale.
delay_figure=5
if (( $figure==$delay_figure )) ; then
y_max=250
y_max=400
else # Take y_max = 1.1 * highest plot value.
# Since only the optimal bitrate for the first flow is being ploted,