src/tests/perf_tests/DawnPerfTest.cpp - dawn - Git at Google

 // Copyright 2019 The Dawn Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "tests/perf_tests/DawnPerfTest.h"

 #include <algorithm>
 #include <fstream>
 #include <limits>

 #include "common/Assert.h"
 #include "common/Log.h"
 #include "dawn_platform/tracing/TraceEvent.h"
 #include "tests/perf_tests/DawnPerfTestPlatform.h"
 #include "utils/Timer.h"

 namespace {

     DawnPerfTestEnvironment* gTestEnv = nullptr;

     void DumpTraceEventsToJSONFile(
         const std::vector<DawnPerfTestPlatform::TraceEvent>& traceEventBuffer,
         const char* traceFile) {
         std::ofstream outFile;
         outFile.open(traceFile, std::ios_base::app);

         for (const DawnPerfTestPlatform::TraceEvent& traceEvent : traceEventBuffer) {
             const char* category = nullptr;
             switch (traceEvent.category) {
                 case dawn_platform::TraceCategory::General:
                     category = "general";
                     break;
                 case dawn_platform::TraceCategory::Validation:
                     category = "validation";
                     break;
                 case dawn_platform::TraceCategory::Recording:
                     category = "recording";
                     break;
                 case dawn_platform::TraceCategory::GPUWork:
                     category = "gpu";
                     break;
                 default:
                     UNREACHABLE();
             }

             uint64_t microseconds = static_cast<uint64_t>(traceEvent.timestamp * 1000.0 * 1000.0);

             outFile << ", { "
                     << "\"name\": \"" << traceEvent.name << "\", "
                     << "\"cat\": \"" << category << "\", "
                     << "\"ph\": \"" << traceEvent.phase << "\", "
                     << "\"id\": " << traceEvent.id << ", "
                     << "\"tid\": " << traceEvent.threadId << ", "
                     << "\"ts\": " << microseconds << ", "
                     << "\"pid\": \"Dawn\""
                     << " }";
         }
         outFile.close();
     }

 }  // namespace

 void InitDawnPerfTestEnvironment(int argc, char** argv) {
     gTestEnv = new DawnPerfTestEnvironment(argc, argv);
     DawnTestEnvironment::SetEnvironment(gTestEnv);
     testing::AddGlobalTestEnvironment(gTestEnv);
 }

 DawnPerfTestEnvironment::DawnPerfTestEnvironment(int argc, char** argv)
     : DawnTestEnvironment(argc, argv) {
     size_t argLen = 0;  // Set when parsing --arg=X arguments
     for (int i = 1; i < argc; ++i) {
         if (strcmp("--calibration", argv[i]) == 0) {
             mIsCalibrating = true;
             continue;
         }

         constexpr const char kOverrideStepsArg[] = "--override-steps=";
         argLen = sizeof(kOverrideStepsArg) - 1;
         if (strncmp(argv[i], kOverrideStepsArg, argLen) == 0) {
             const char* overrideSteps = argv[i] + argLen;
             if (overrideSteps[0] != '\0') {
                 mOverrideStepsToRun = strtoul(overrideSteps, nullptr, 0);
             }
             continue;
         }

         constexpr const char kTraceFileArg[] = "--trace-file=";
         argLen = sizeof(kTraceFileArg) - 1;
         if (strncmp(argv[i], kTraceFileArg, argLen) == 0) {
             const char* traceFile = argv[i] + argLen;
             if (traceFile[0] != '\0') {
                 mTraceFile = traceFile;
             }
             continue;
         }

         if (strcmp("-h", argv[i]) == 0 || strcmp("--help", argv[i]) == 0) {
             dawn::InfoLog()
                 << "Additional flags:"
                 << " [--calibration] [--override-steps=x] [--trace-file=file]\n"
                 << "  --calibration: Only run calibration. Calibration allows the perf test"
                    " runner script to save some time.\n"
                 << " --override-steps: Set a fixed number of steps to run for each test\n"
                 << " --trace-file: The file to dump trace results.\n";
             continue;
         }
     }
 }

 DawnPerfTestEnvironment::~DawnPerfTestEnvironment() = default;

 void DawnPerfTestEnvironment::SetUp() {
     DawnTestEnvironment::SetUp();

     mPlatform = std::make_unique<DawnPerfTestPlatform>();
     mInstance->SetPlatform(mPlatform.get());

     // Begin writing the trace event array.
     if (mTraceFile != nullptr) {
         std::ofstream outFile;
         outFile.open(mTraceFile);
         outFile << "{ \"traceEvents\": [";
         outFile << "{}";  // Dummy object so trace events can always prepend a comma
         outFile.flush();
         outFile.close();
     }
 }

 void DawnPerfTestEnvironment::TearDown() {
     // End writing the trace event array.
     if (mTraceFile != nullptr) {
         std::vector<DawnPerfTestPlatform::TraceEvent> traceEventBuffer =
             mPlatform->AcquireTraceEventBuffer();

         // Write remaining trace events.
         DumpTraceEventsToJSONFile(traceEventBuffer, mTraceFile);

         std::ofstream outFile;
         outFile.open(mTraceFile, std::ios_base::app);
         outFile << "]}";
         outFile << std::endl;
         outFile.close();
     }

     DawnTestEnvironment::TearDown();
 }

 bool DawnPerfTestEnvironment::IsCalibrating() const {
     return mIsCalibrating;
 }

 unsigned int DawnPerfTestEnvironment::OverrideStepsToRun() const {
     return mOverrideStepsToRun;
 }

 const char* DawnPerfTestEnvironment::GetTraceFile() const {
     return mTraceFile;
 }

 DawnPerfTestPlatform* DawnPerfTestEnvironment::GetPlatform() const {
     return mPlatform.get();
 }

 DawnPerfTestBase::DawnPerfTestBase(DawnTestBase* test,
                                    unsigned int iterationsPerStep,
                                    unsigned int maxStepsInFlight)
     : mTest(test),
       mIterationsPerStep(iterationsPerStep),
       mMaxStepsInFlight(maxStepsInFlight),
       mTimer(utils::CreateTimer()) {
 }

 DawnPerfTestBase::~DawnPerfTestBase() = default;

 void DawnPerfTestBase::AbortTest() {
     mRunning = false;
 }

 void DawnPerfTestBase::RunTest() {
     if (gTestEnv->OverrideStepsToRun() == 0) {
         // Run to compute the approximate number of steps to perform.
         mStepsToRun = std::numeric_limits<unsigned int>::max();

         // Do a warmup run for calibration.
         DoRunLoop(kCalibrationRunTimeSeconds);
         DoRunLoop(kCalibrationRunTimeSeconds);

         // Scale steps down according to the time that exceeded one second.
         double scale = kCalibrationRunTimeSeconds / mTimer->GetElapsedTime();
         mStepsToRun = static_cast<unsigned int>(static_cast<double>(mNumStepsPerformed) * scale);

         // Calibration allows the perf test runner script to save some time.
         if (gTestEnv->IsCalibrating()) {
             PrintResult("steps", mStepsToRun, "count", false);
             return;
         }
     } else {
         mStepsToRun = gTestEnv->OverrideStepsToRun();
     }

     // Do another warmup run. Seems to consistently improve results.
     DoRunLoop(kMaximumRunTimeSeconds);

     DawnPerfTestPlatform* platform =
         reinterpret_cast<DawnPerfTestPlatform*>(gTestEnv->GetPlatform());
     const char* testName = ::testing::UnitTest::GetInstance()->current_test_info()->name();

     // Only enable trace event recording in this section.
     // We don't care about trace events during warmup and calibration.
     platform->EnableTraceEventRecording(true);
     {
         TRACE_EVENT0(platform, General, testName);
         for (unsigned int trial = 0; trial < kNumTrials; ++trial) {
             TRACE_EVENT0(platform, General, "Trial");
             DoRunLoop(kMaximumRunTimeSeconds);
             OutputResults();
         }
     }
     platform->EnableTraceEventRecording(false);
 }

 void DawnPerfTestBase::DoRunLoop(double maxRunTime) {
     dawn_platform::Platform* platform = gTestEnv->GetPlatform();

     mNumStepsPerformed = 0;
     mCpuTime = 0;
     mRunning = true;

     uint64_t finishedIterations = 0;
     uint64_t submittedIterations = 0;

     mTimer->Start();

     // This loop can be canceled by calling AbortTest().
     while (mRunning) {
         // Wait if there are too many steps in flight on the GPU.
         while (submittedIterations - finishedIterations >= mMaxStepsInFlight) {
             mTest->WaitABit();
         }

         TRACE_EVENT0(platform, General, "Step");
         double stepStart = mTimer->GetElapsedTime();
         Step();
         mCpuTime += mTimer->GetElapsedTime() - stepStart;

         submittedIterations++;
         mTest->queue.OnSubmittedWorkDone(
             0u,
             [](WGPUQueueWorkDoneStatus, void* userdata) {
                 uint64_t* counter = static_cast<uint64_t*>(userdata);
                 (*counter)++;
             },
             &finishedIterations);

         if (mRunning) {
             ++mNumStepsPerformed;
             if (mTimer->GetElapsedTime() > maxRunTime) {
                 mRunning = false;
             } else if (mNumStepsPerformed >= mStepsToRun) {
                 mRunning = false;
             }
         }
     }

     // Wait for all GPU commands to complete.
     // TODO(enga): When Dawn has multiple backgrounds threads, add a Device::WaitForIdleForTesting()
     // which waits for all threads to stop doing work. When we output results, there should
     // be no additional incoming trace events.
     while (submittedIterations != finishedIterations) {
         mTest->WaitABit();
     }

     mTimer->Stop();
 }

 void DawnPerfTestBase::OutputResults() {
     // TODO(enga): When Dawn has multiple backgrounds threads, add a Device::WaitForIdleForTesting()
     // which waits for all threads to stop doing work. When we output results, there should
     // be no additional incoming trace events.
     DawnPerfTestPlatform* platform =
         reinterpret_cast<DawnPerfTestPlatform*>(gTestEnv->GetPlatform());

     std::vector<DawnPerfTestPlatform::TraceEvent> traceEventBuffer =
         platform->AcquireTraceEventBuffer();

     struct EventTracker {
         double start = std::numeric_limits<double>::max();
         double end = 0;
         uint32_t count = 0;
     };

     EventTracker validationTracker = {};
     EventTracker recordingTracker = {};

     double totalValidationTime = 0;
     double totalRecordingTime = 0;

     // Note: We assume END timestamps always come after their corresponding BEGIN timestamps.
     // TODO(enga): When Dawn has multiple threads, stratify by thread id.
     for (const DawnPerfTestPlatform::TraceEvent& traceEvent : traceEventBuffer) {
         EventTracker* tracker = nullptr;
         double* totalTime = nullptr;

         switch (traceEvent.category) {
             case dawn_platform::TraceCategory::Validation:
                 tracker = &validationTracker;
                 totalTime = &totalValidationTime;
                 break;
             case dawn_platform::TraceCategory::Recording:
                 tracker = &recordingTracker;
                 totalTime = &totalRecordingTime;
                 break;
             default:
                 break;
         }

         if (tracker == nullptr) {
             continue;
         }

         if (traceEvent.phase == TRACE_EVENT_PHASE_BEGIN) {
             tracker->start = std::min(tracker->start, traceEvent.timestamp);
             tracker->count++;
         }

         if (traceEvent.phase == TRACE_EVENT_PHASE_END) {
             tracker->end = std::max(tracker->end, traceEvent.timestamp);
             ASSERT(tracker->count > 0);
             tracker->count--;

             if (tracker->count == 0) {
                 *totalTime += (tracker->end - tracker->start);
                 *tracker = {};
             }
         }
     }

     PrintPerIterationResultFromSeconds("wall_time", mTimer->GetElapsedTime(), true);
     PrintPerIterationResultFromSeconds("cpu_time", mCpuTime, true);
     PrintPerIterationResultFromSeconds("validation_time", totalValidationTime, true);
     PrintPerIterationResultFromSeconds("recording_time", totalRecordingTime, true);

     const char* traceFile = gTestEnv->GetTraceFile();
     if (traceFile != nullptr) {
         DumpTraceEventsToJSONFile(traceEventBuffer, traceFile);
     }
 }

 void DawnPerfTestBase::PrintPerIterationResultFromSeconds(const std::string& trace,
                                                           double valueInSeconds,
                                                           bool important) const {
     if (valueInSeconds == 0) {
         return;
     }

     double secondsPerIteration =
         valueInSeconds / static_cast<double>(mNumStepsPerformed * mIterationsPerStep);

     // Give the result a different name to ensure separate graphs if we transition.
     if (secondsPerIteration > 1) {
         PrintResult(trace, secondsPerIteration * 1e3, "ms", important);
     } else if (secondsPerIteration > 1e-3) {
         PrintResult(trace, secondsPerIteration * 1e6, "us", important);
     } else {
         PrintResult(trace, secondsPerIteration * 1e9, "ns", important);
     }
 }

 void DawnPerfTestBase::PrintResult(const std::string& trace,
                                    double value,
                                    const std::string& units,
                                    bool important) const {
     PrintResultImpl(trace, std::to_string(value), units, important);
 }

 void DawnPerfTestBase::PrintResult(const std::string& trace,
                                    unsigned int value,
                                    const std::string& units,
                                    bool important) const {
     PrintResultImpl(trace, std::to_string(value), units, important);
 }

 void DawnPerfTestBase::PrintResultImpl(const std::string& trace,
                                        const std::string& value,
                                        const std::string& units,
                                        bool important) const {
     const ::testing::TestInfo* const testInfo =
         ::testing::UnitTest::GetInstance()->current_test_info();

     std::string metric = std::string(testInfo->test_suite_name()) + "." + trace;

     std::string story = testInfo->name();
     std::replace(story.begin(), story.end(), '/', '_');

     // The results are printed according to the format specified at
     // [chromium]//src/tools/perf/generate_legacy_perf_dashboard_json.py
     dawn::InfoLog() << (important ? "*" : "") << "RESULT " << metric << ": " << story << "= "
                     << value << " " << units;
 }
	// Copyright 2019 The Dawn Authors
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "tests/perf_tests/DawnPerfTest.h"

	#include <algorithm>
	#include <fstream>
	#include <limits>

	#include "common/Assert.h"
	#include "common/Log.h"
	#include "dawn_platform/tracing/TraceEvent.h"
	#include "tests/perf_tests/DawnPerfTestPlatform.h"
	#include "utils/Timer.h"

	namespace {

	DawnPerfTestEnvironment* gTestEnv = nullptr;

	void DumpTraceEventsToJSONFile(
	const std::vector<DawnPerfTestPlatform::TraceEvent>& traceEventBuffer,
	const char* traceFile) {
	std::ofstream outFile;
	outFile.open(traceFile, std::ios_base::app);

	for (const DawnPerfTestPlatform::TraceEvent& traceEvent : traceEventBuffer) {
	const char* category = nullptr;
	switch (traceEvent.category) {
	case dawn_platform::TraceCategory::General:
	category = "general";
	break;
	case dawn_platform::TraceCategory::Validation:
	category = "validation";
	break;
	case dawn_platform::TraceCategory::Recording:
	category = "recording";
	break;
	case dawn_platform::TraceCategory::GPUWork:
	category = "gpu";
	break;
	default:
	UNREACHABLE();
	}

	uint64_t microseconds = static_cast<uint64_t>(traceEvent.timestamp * 1000.0 * 1000.0);

	outFile << ", { "
	<< "\"name\": \"" << traceEvent.name << "\", "
	<< "\"cat\": \"" << category << "\", "
	<< "\"ph\": \"" << traceEvent.phase << "\", "
	<< "\"id\": " << traceEvent.id << ", "
	<< "\"tid\": " << traceEvent.threadId << ", "
	<< "\"ts\": " << microseconds << ", "
	<< "\"pid\": \"Dawn\""
	<< " }";
	}
	outFile.close();
	}

	} // namespace

	void InitDawnPerfTestEnvironment(int argc, char** argv) {
	gTestEnv = new DawnPerfTestEnvironment(argc, argv);
	DawnTestEnvironment::SetEnvironment(gTestEnv);
	testing::AddGlobalTestEnvironment(gTestEnv);
	}

	DawnPerfTestEnvironment::DawnPerfTestEnvironment(int argc, char** argv)
	: DawnTestEnvironment(argc, argv) {
	size_t argLen = 0; // Set when parsing --arg=X arguments
	for (int i = 1; i < argc; ++i) {
	if (strcmp("--calibration", argv[i]) == 0) {
	mIsCalibrating = true;
	continue;
	}

	constexpr const char kOverrideStepsArg[] = "--override-steps=";
	argLen = sizeof(kOverrideStepsArg) - 1;
	if (strncmp(argv[i], kOverrideStepsArg, argLen) == 0) {
	const char* overrideSteps = argv[i] + argLen;
	if (overrideSteps[0] != '\0') {
	mOverrideStepsToRun = strtoul(overrideSteps, nullptr, 0);
	}
	continue;
	}

	constexpr const char kTraceFileArg[] = "--trace-file=";
	argLen = sizeof(kTraceFileArg) - 1;
	if (strncmp(argv[i], kTraceFileArg, argLen) == 0) {
	const char* traceFile = argv[i] + argLen;
	if (traceFile[0] != '\0') {
	mTraceFile = traceFile;
	}
	continue;
	}

	if (strcmp("-h", argv[i]) == 0 \|\| strcmp("--help", argv[i]) == 0) {
	dawn::InfoLog()
	<< "Additional flags:"
	<< " [--calibration] [--override-steps=x] [--trace-file=file]\n"
	<< " --calibration: Only run calibration. Calibration allows the perf test"
	" runner script to save some time.\n"
	<< " --override-steps: Set a fixed number of steps to run for each test\n"
	<< " --trace-file: The file to dump trace results.\n";
	continue;
	}
	}
	}

	DawnPerfTestEnvironment::~DawnPerfTestEnvironment() = default;

	void DawnPerfTestEnvironment::SetUp() {
	DawnTestEnvironment::SetUp();

	mPlatform = std::make_unique<DawnPerfTestPlatform>();
	mInstance->SetPlatform(mPlatform.get());

	// Begin writing the trace event array.
	if (mTraceFile != nullptr) {
	std::ofstream outFile;
	outFile.open(mTraceFile);
	outFile << "{ \"traceEvents\": [";
	outFile << "{}"; // Dummy object so trace events can always prepend a comma
	outFile.flush();
	outFile.close();
	}
	}

	void DawnPerfTestEnvironment::TearDown() {
	// End writing the trace event array.
	if (mTraceFile != nullptr) {
	std::vector<DawnPerfTestPlatform::TraceEvent> traceEventBuffer =
	mPlatform->AcquireTraceEventBuffer();

	// Write remaining trace events.
	DumpTraceEventsToJSONFile(traceEventBuffer, mTraceFile);

	std::ofstream outFile;
	outFile.open(mTraceFile, std::ios_base::app);
	outFile << "]}";
	outFile << std::endl;
	outFile.close();
	}

	DawnTestEnvironment::TearDown();
	}

	bool DawnPerfTestEnvironment::IsCalibrating() const {
	return mIsCalibrating;
	}

	unsigned int DawnPerfTestEnvironment::OverrideStepsToRun() const {
	return mOverrideStepsToRun;
	}

	const char* DawnPerfTestEnvironment::GetTraceFile() const {
	return mTraceFile;
	}

	DawnPerfTestPlatform* DawnPerfTestEnvironment::GetPlatform() const {
	return mPlatform.get();
	}

	DawnPerfTestBase::DawnPerfTestBase(DawnTestBase* test,
	unsigned int iterationsPerStep,
	unsigned int maxStepsInFlight)
	: mTest(test),
	mIterationsPerStep(iterationsPerStep),
	mMaxStepsInFlight(maxStepsInFlight),
	mTimer(utils::CreateTimer()) {
	}

	DawnPerfTestBase::~DawnPerfTestBase() = default;

	void DawnPerfTestBase::AbortTest() {
	mRunning = false;
	}

	void DawnPerfTestBase::RunTest() {
	if (gTestEnv->OverrideStepsToRun() == 0) {
	// Run to compute the approximate number of steps to perform.
	mStepsToRun = std::numeric_limits<unsigned int>::max();

	// Do a warmup run for calibration.
	DoRunLoop(kCalibrationRunTimeSeconds);
	DoRunLoop(kCalibrationRunTimeSeconds);

	// Scale steps down according to the time that exceeded one second.
	double scale = kCalibrationRunTimeSeconds / mTimer->GetElapsedTime();
	mStepsToRun = static_cast<unsigned int>(static_cast<double>(mNumStepsPerformed) * scale);

	// Calibration allows the perf test runner script to save some time.
	if (gTestEnv->IsCalibrating()) {
	PrintResult("steps", mStepsToRun, "count", false);
	return;
	}
	} else {
	mStepsToRun = gTestEnv->OverrideStepsToRun();
	}

	// Do another warmup run. Seems to consistently improve results.
	DoRunLoop(kMaximumRunTimeSeconds);

	DawnPerfTestPlatform* platform =
	reinterpret_cast<DawnPerfTestPlatform*>(gTestEnv->GetPlatform());
	const char* testName = ::testing::UnitTest::GetInstance()->current_test_info()->name();

	// Only enable trace event recording in this section.
	// We don't care about trace events during warmup and calibration.
	platform->EnableTraceEventRecording(true);
	{
	TRACE_EVENT0(platform, General, testName);
	for (unsigned int trial = 0; trial < kNumTrials; ++trial) {
	TRACE_EVENT0(platform, General, "Trial");
	DoRunLoop(kMaximumRunTimeSeconds);
	OutputResults();
	}
	}
	platform->EnableTraceEventRecording(false);
	}

	void DawnPerfTestBase::DoRunLoop(double maxRunTime) {
	dawn_platform::Platform* platform = gTestEnv->GetPlatform();

	mNumStepsPerformed = 0;
	mCpuTime = 0;
	mRunning = true;

	uint64_t finishedIterations = 0;
	uint64_t submittedIterations = 0;

	mTimer->Start();

	// This loop can be canceled by calling AbortTest().
	while (mRunning) {
	// Wait if there are too many steps in flight on the GPU.
	while (submittedIterations - finishedIterations >= mMaxStepsInFlight) {
	mTest->WaitABit();
	}

	TRACE_EVENT0(platform, General, "Step");
	double stepStart = mTimer->GetElapsedTime();
	Step();
	mCpuTime += mTimer->GetElapsedTime() - stepStart;

	submittedIterations++;
	mTest->queue.OnSubmittedWorkDone(
	0u,
	[](WGPUQueueWorkDoneStatus, void* userdata) {
	uint64_t* counter = static_cast<uint64_t*>(userdata);
	(*counter)++;
	},
	&finishedIterations);

	if (mRunning) {
	++mNumStepsPerformed;
	if (mTimer->GetElapsedTime() > maxRunTime) {
	mRunning = false;
	} else if (mNumStepsPerformed >= mStepsToRun) {
	mRunning = false;
	}
	}
	}

	// Wait for all GPU commands to complete.
	// TODO(enga): When Dawn has multiple backgrounds threads, add a Device::WaitForIdleForTesting()
	// which waits for all threads to stop doing work. When we output results, there should
	// be no additional incoming trace events.
	while (submittedIterations != finishedIterations) {
	mTest->WaitABit();
	}

	mTimer->Stop();
	}

	void DawnPerfTestBase::OutputResults() {
	// TODO(enga): When Dawn has multiple backgrounds threads, add a Device::WaitForIdleForTesting()
	// which waits for all threads to stop doing work. When we output results, there should
	// be no additional incoming trace events.
	DawnPerfTestPlatform* platform =
	reinterpret_cast<DawnPerfTestPlatform*>(gTestEnv->GetPlatform());

	std::vector<DawnPerfTestPlatform::TraceEvent> traceEventBuffer =
	platform->AcquireTraceEventBuffer();

	struct EventTracker {
	double start = std::numeric_limits<double>::max();
	double end = 0;
	uint32_t count = 0;
	};

	EventTracker validationTracker = {};
	EventTracker recordingTracker = {};

	double totalValidationTime = 0;
	double totalRecordingTime = 0;

	// Note: We assume END timestamps always come after their corresponding BEGIN timestamps.
	// TODO(enga): When Dawn has multiple threads, stratify by thread id.
	for (const DawnPerfTestPlatform::TraceEvent& traceEvent : traceEventBuffer) {
	EventTracker* tracker = nullptr;
	double* totalTime = nullptr;

	switch (traceEvent.category) {
	case dawn_platform::TraceCategory::Validation:
	tracker = &validationTracker;
	totalTime = &totalValidationTime;
	break;
	case dawn_platform::TraceCategory::Recording:
	tracker = &recordingTracker;
	totalTime = &totalRecordingTime;
	break;
	default:
	break;
	}

	if (tracker == nullptr) {
	continue;
	}

	if (traceEvent.phase == TRACE_EVENT_PHASE_BEGIN) {
	tracker->start = std::min(tracker->start, traceEvent.timestamp);
	tracker->count++;
	}

	if (traceEvent.phase == TRACE_EVENT_PHASE_END) {
	tracker->end = std::max(tracker->end, traceEvent.timestamp);
	ASSERT(tracker->count > 0);
	tracker->count--;

	if (tracker->count == 0) {
	*totalTime += (tracker->end - tracker->start);
	*tracker = {};
	}
	}
	}

	PrintPerIterationResultFromSeconds("wall_time", mTimer->GetElapsedTime(), true);
	PrintPerIterationResultFromSeconds("cpu_time", mCpuTime, true);
	PrintPerIterationResultFromSeconds("validation_time", totalValidationTime, true);
	PrintPerIterationResultFromSeconds("recording_time", totalRecordingTime, true);

	const char* traceFile = gTestEnv->GetTraceFile();
	if (traceFile != nullptr) {
	DumpTraceEventsToJSONFile(traceEventBuffer, traceFile);
	}
	}

	void DawnPerfTestBase::PrintPerIterationResultFromSeconds(const std::string& trace,
	double valueInSeconds,
	bool important) const {
	if (valueInSeconds == 0) {
	return;
	}

	double secondsPerIteration =
	valueInSeconds / static_cast<double>(mNumStepsPerformed * mIterationsPerStep);

	// Give the result a different name to ensure separate graphs if we transition.
	if (secondsPerIteration > 1) {
	PrintResult(trace, secondsPerIteration * 1e3, "ms", important);
	} else if (secondsPerIteration > 1e-3) {
	PrintResult(trace, secondsPerIteration * 1e6, "us", important);
	} else {
	PrintResult(trace, secondsPerIteration * 1e9, "ns", important);
	}
	}

	void DawnPerfTestBase::PrintResult(const std::string& trace,
	double value,
	const std::string& units,
	bool important) const {
	PrintResultImpl(trace, std::to_string(value), units, important);
	}

	void DawnPerfTestBase::PrintResult(const std::string& trace,
	unsigned int value,
	const std::string& units,
	bool important) const {
	PrintResultImpl(trace, std::to_string(value), units, important);
	}

	void DawnPerfTestBase::PrintResultImpl(const std::string& trace,
	const std::string& value,
	const std::string& units,
	bool important) const {
	const ::testing::TestInfo* const testInfo =
	::testing::UnitTest::GetInstance()->current_test_info();

	std::string metric = std::string(testInfo->test_suite_name()) + "." + trace;

	std::string story = testInfo->name();
	std::replace(story.begin(), story.end(), '/', '_');

	// The results are printed according to the format specified at
	// [chromium]//src/tools/perf/generate_legacy_perf_dashboard_json.py
	dawn::InfoLog() << (important ? "*" : "") << "RESULT " << metric << ": " << story << "= "
	<< value << " " << units;
	}