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/*
* Copyright (c) 2013 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/video/overuse_frame_detector.h"
#include <assert.h>
#include <math.h>
#include <algorithm>
#include <list>
#include <map>
#include "webrtc/base/checks.h"
#include "webrtc/base/exp_filter.h"
#include "webrtc/base/logging.h"
#include "webrtc/common_video/include/frame_callback.h"
#include "webrtc/system_wrappers/include/clock.h"
#include "webrtc/video_frame.h"
#if defined(WEBRTC_MAC) && !defined(WEBRTC_IOS)
#include <mach/mach.h>
#endif // defined(WEBRTC_MAC) && !defined(WEBRTC_IOS)
namespace webrtc {
namespace {
const int64_t kProcessIntervalMs = 5000;
// Delay between consecutive rampups. (Used for quick recovery.)
const int kQuickRampUpDelayMs = 10 * 1000;
// Delay between rampup attempts. Initially uses standard, scales up to max.
const int kStandardRampUpDelayMs = 40 * 1000;
const int kMaxRampUpDelayMs = 240 * 1000;
// Expontential back-off factor, to prevent annoying up-down behaviour.
const double kRampUpBackoffFactor = 2.0;
// Max number of overuses detected before always applying the rampup delay.
const int kMaxOverusesBeforeApplyRampupDelay = 4;
// The maximum exponent to use in VCMExpFilter.
const float kSampleDiffMs = 33.0f;
const float kMaxExp = 7.0f;
} // namespace
CpuOveruseOptions::CpuOveruseOptions()
: high_encode_usage_threshold_percent(85),
frame_timeout_interval_ms(1500),
min_frame_samples(120),
min_process_count(3),
high_threshold_consecutive_count(2) {
#if defined(WEBRTC_MAC) && !defined(WEBRTC_IOS)
// This is proof-of-concept code for letting the physical core count affect
// the interval into which we attempt to scale. For now, the code is Mac OS
// specific, since that's the platform were we saw most problems.
// TODO(torbjorng): Enhance SystemInfo to return this metric.
mach_port_t mach_host = mach_host_self();
host_basic_info hbi = {};
mach_msg_type_number_t info_count = HOST_BASIC_INFO_COUNT;
kern_return_t kr =
host_info(mach_host, HOST_BASIC_INFO, reinterpret_cast<host_info_t>(&hbi),
&info_count);
mach_port_deallocate(mach_task_self(), mach_host);
int n_physical_cores;
if (kr != KERN_SUCCESS) {
// If we couldn't get # of physical CPUs, don't panic. Assume we have 1.
n_physical_cores = 1;
LOG(LS_ERROR) << "Failed to determine number of physical cores, assuming 1";
} else {
n_physical_cores = hbi.physical_cpu;
LOG(LS_INFO) << "Number of physical cores:" << n_physical_cores;
}
// Change init list default for few core systems. The assumption here is that
// encoding, which we measure here, takes about 1/4 of the processing of a
// two-way call. This is roughly true for x86 using both vp8 and vp9 without
// hardware encoding. Since we don't affect the incoming stream here, we only
// control about 1/2 of the total processing needs, but this is not taken into
// account.
if (n_physical_cores == 1)
high_encode_usage_threshold_percent = 20; // Roughly 1/4 of 100%.
else if (n_physical_cores == 2)
high_encode_usage_threshold_percent = 40; // Roughly 1/4 of 200%.
#endif // defined(WEBRTC_MAC) && !defined(WEBRTC_IOS)
// Note that we make the interval 2x+epsilon wide, since libyuv scaling steps
// are close to that (when squared). This wide interval makes sure that
// scaling up or down does not jump all the way across the interval.
low_encode_usage_threshold_percent =
(high_encode_usage_threshold_percent - 1) / 2;
}
// Class for calculating the processing usage on the send-side (the average
// processing time of a frame divided by the average time difference between
// captured frames).
class OveruseFrameDetector::SendProcessingUsage {
public:
explicit SendProcessingUsage(const CpuOveruseOptions& options)
: kWeightFactorFrameDiff(0.998f),
kWeightFactorProcessing(0.995f),
kInitialSampleDiffMs(40.0f),
kMaxSampleDiffMs(45.0f),
count_(0),
options_(options),
filtered_processing_ms_(new rtc::ExpFilter(kWeightFactorProcessing)),
filtered_frame_diff_ms_(new rtc::ExpFilter(kWeightFactorFrameDiff)) {
Reset();
}
~SendProcessingUsage() {}
void Reset() {
count_ = 0;
filtered_frame_diff_ms_->Reset(kWeightFactorFrameDiff);
filtered_frame_diff_ms_->Apply(1.0f, kInitialSampleDiffMs);
filtered_processing_ms_->Reset(kWeightFactorProcessing);
filtered_processing_ms_->Apply(1.0f, InitialProcessingMs());
}
void AddCaptureSample(float sample_ms) {
float exp = sample_ms / kSampleDiffMs;
exp = std::min(exp, kMaxExp);
filtered_frame_diff_ms_->Apply(exp, sample_ms);
}
void AddSample(float processing_ms, int64_t diff_last_sample_ms) {
++count_;
float exp = diff_last_sample_ms / kSampleDiffMs;
exp = std::min(exp, kMaxExp);
filtered_processing_ms_->Apply(exp, processing_ms);
}
int Value() const {
if (count_ < static_cast<uint32_t>(options_.min_frame_samples)) {
return static_cast<int>(InitialUsageInPercent() + 0.5f);
}
float frame_diff_ms = std::max(filtered_frame_diff_ms_->filtered(), 1.0f);
frame_diff_ms = std::min(frame_diff_ms, kMaxSampleDiffMs);
float encode_usage_percent =
100.0f * filtered_processing_ms_->filtered() / frame_diff_ms;
return static_cast<int>(encode_usage_percent + 0.5);
}
private:
float InitialUsageInPercent() const {
// Start in between the underuse and overuse threshold.
return (options_.low_encode_usage_threshold_percent +
options_.high_encode_usage_threshold_percent) / 2.0f;
}
float InitialProcessingMs() const {
return InitialUsageInPercent() * kInitialSampleDiffMs / 100;
}
const float kWeightFactorFrameDiff;
const float kWeightFactorProcessing;
const float kInitialSampleDiffMs;
const float kMaxSampleDiffMs;
uint64_t count_;
const CpuOveruseOptions options_;
std::unique_ptr<rtc::ExpFilter> filtered_processing_ms_;
std::unique_ptr<rtc::ExpFilter> filtered_frame_diff_ms_;
};
OveruseFrameDetector::OveruseFrameDetector(
Clock* clock,
const CpuOveruseOptions& options,
CpuOveruseObserver* observer,
EncodedFrameObserver* encoder_timing,
CpuOveruseMetricsObserver* metrics_observer)
: options_(options),
observer_(observer),
encoder_timing_(encoder_timing),
metrics_observer_(metrics_observer),
clock_(clock),
num_process_times_(0),
last_capture_time_ms_(-1),
last_processed_capture_time_ms_(-1),
num_pixels_(0),
next_process_time_ms_(clock_->TimeInMilliseconds()),
last_overuse_time_ms_(-1),
checks_above_threshold_(0),
num_overuse_detections_(0),
last_rampup_time_ms_(-1),
in_quick_rampup_(false),
current_rampup_delay_ms_(kStandardRampUpDelayMs),
usage_(new SendProcessingUsage(options)) {
RTC_DCHECK(metrics_observer);
processing_thread_.DetachFromThread();
}
OveruseFrameDetector::~OveruseFrameDetector() {
}
void OveruseFrameDetector::EncodedFrameTimeMeasured(int encode_duration_ms) {
if (!metrics_)
metrics_ = rtc::Optional<CpuOveruseMetrics>(CpuOveruseMetrics());
metrics_->encode_usage_percent = usage_->Value();
metrics_observer_->OnEncodedFrameTimeMeasured(encode_duration_ms, *metrics_);
}
int64_t OveruseFrameDetector::TimeUntilNextProcess() {
RTC_DCHECK(processing_thread_.CalledOnValidThread());
return next_process_time_ms_ - clock_->TimeInMilliseconds();
}
bool OveruseFrameDetector::FrameSizeChanged(int num_pixels) const {
if (num_pixels != num_pixels_) {
return true;
}
return false;
}
bool OveruseFrameDetector::FrameTimeoutDetected(int64_t now) const {
if (last_capture_time_ms_ == -1)
return false;
return (now - last_capture_time_ms_) > options_.frame_timeout_interval_ms;
}
void OveruseFrameDetector::ResetAll(int num_pixels) {
num_pixels_ = num_pixels;
usage_->Reset();
frame_timing_.clear();
last_capture_time_ms_ = -1;
last_processed_capture_time_ms_ = -1;
num_process_times_ = 0;
metrics_ = rtc::Optional<CpuOveruseMetrics>();
}
void OveruseFrameDetector::FrameCaptured(const VideoFrame& frame) {
rtc::CritScope cs(&crit_);
int64_t now = clock_->TimeInMilliseconds();
if (FrameSizeChanged(frame.width() * frame.height()) ||
FrameTimeoutDetected(now)) {
ResetAll(frame.width() * frame.height());
}
if (last_capture_time_ms_ != -1)
usage_->AddCaptureSample(now - last_capture_time_ms_);
last_capture_time_ms_ = now;
frame_timing_.push_back(
FrameTiming(frame.ntp_time_ms(), frame.timestamp(), now));
}
void OveruseFrameDetector::FrameSent(uint32_t timestamp) {
rtc::CritScope cs(&crit_);
// Delay before reporting actual encoding time, used to have the ability to
// detect total encoding time when encoding more than one layer. Encoding is
// here assumed to finish within a second (or that we get enough long-time
// samples before one second to trigger an overuse even when this is not the
// case).
static const int64_t kEncodingTimeMeasureWindowMs = 1000;
int64_t now = clock_->TimeInMilliseconds();
for (auto& it : frame_timing_) {
if (it.timestamp == timestamp) {
it.last_send_ms = now;
break;
}
}
// TODO(pbos): Handle the case/log errors when not finding the corresponding
// frame (either very slow encoding or incorrect wrong timestamps returned
// from the encoder).
// This is currently the case for all frames on ChromeOS, so logging them
// would be spammy, and triggering overuse would be wrong.
// https://crbug.com/350106
while (!frame_timing_.empty()) {
FrameTiming timing = frame_timing_.front();
if (now - timing.capture_ms < kEncodingTimeMeasureWindowMs)
break;
if (timing.last_send_ms != -1) {
int encode_duration_ms =
static_cast<int>(timing.last_send_ms - timing.capture_ms);
if (encoder_timing_) {
encoder_timing_->OnEncodeTiming(timing.capture_ntp_ms,
encode_duration_ms);
}
if (last_processed_capture_time_ms_ != -1) {
int64_t diff_ms = timing.capture_ms - last_processed_capture_time_ms_;
usage_->AddSample(encode_duration_ms, diff_ms);
}
last_processed_capture_time_ms_ = timing.capture_ms;
EncodedFrameTimeMeasured(encode_duration_ms);
}
frame_timing_.pop_front();
}
}
void OveruseFrameDetector::Process() {
RTC_DCHECK(processing_thread_.CalledOnValidThread());
int64_t now = clock_->TimeInMilliseconds();
// Used to protect against Process() being called too often.
if (now < next_process_time_ms_)
return;
next_process_time_ms_ = now + kProcessIntervalMs;
CpuOveruseMetrics current_metrics;
{
rtc::CritScope cs(&crit_);
++num_process_times_;
if (num_process_times_ <= options_.min_process_count || !metrics_)
return;
current_metrics = *metrics_;
}
if (IsOverusing(current_metrics)) {
// If the last thing we did was going up, and now have to back down, we need
// to check if this peak was short. If so we should back off to avoid going
// back and forth between this load, the system doesn't seem to handle it.
bool check_for_backoff = last_rampup_time_ms_ > last_overuse_time_ms_;
if (check_for_backoff) {
if (now - last_rampup_time_ms_ < kStandardRampUpDelayMs ||
num_overuse_detections_ > kMaxOverusesBeforeApplyRampupDelay) {
// Going up was not ok for very long, back off.
current_rampup_delay_ms_ *= kRampUpBackoffFactor;
if (current_rampup_delay_ms_ > kMaxRampUpDelayMs)
current_rampup_delay_ms_ = kMaxRampUpDelayMs;
} else {
// Not currently backing off, reset rampup delay.
current_rampup_delay_ms_ = kStandardRampUpDelayMs;
}
}
last_overuse_time_ms_ = now;
in_quick_rampup_ = false;
checks_above_threshold_ = 0;
++num_overuse_detections_;
if (observer_)
observer_->OveruseDetected();
} else if (IsUnderusing(current_metrics, now)) {
last_rampup_time_ms_ = now;
in_quick_rampup_ = true;
if (observer_)
observer_->NormalUsage();
}
int rampup_delay =
in_quick_rampup_ ? kQuickRampUpDelayMs : current_rampup_delay_ms_;
LOG(LS_VERBOSE) << " Frame stats: "
<< " encode usage " << current_metrics.encode_usage_percent
<< " overuse detections " << num_overuse_detections_
<< " rampup delay " << rampup_delay;
}
bool OveruseFrameDetector::IsOverusing(const CpuOveruseMetrics& metrics) {
if (metrics.encode_usage_percent >=
options_.high_encode_usage_threshold_percent) {
++checks_above_threshold_;
} else {
checks_above_threshold_ = 0;
}
return checks_above_threshold_ >= options_.high_threshold_consecutive_count;
}
bool OveruseFrameDetector::IsUnderusing(const CpuOveruseMetrics& metrics,
int64_t time_now) {
int delay = in_quick_rampup_ ? kQuickRampUpDelayMs : current_rampup_delay_ms_;
if (time_now < last_rampup_time_ms_ + delay)
return false;
return metrics.encode_usage_percent <
options_.low_encode_usage_threshold_percent;
}
} // namespace webrtc