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Further cleaning of initial commit. Add test.
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maartenarnst committed Jan 26, 2024
1 parent 55ff633 commit 3bca691
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Showing 9 changed files with 150 additions and 26 deletions.
22 changes: 18 additions & 4 deletions include/benchmark/benchmark.h
Original file line number Diff line number Diff line change
Expand Up @@ -126,8 +126,12 @@ template <class Q> int BM_Sequential(benchmark::State& state) {
}
BENCHMARK_TEMPLATE(BM_Sequential, WaitQueue<int>)->Range(1<<0, 1<<10);
Use `Benchmark::MinTime(double t)` to set the minimum time used to run the
benchmark. This option overrides the `benchmark_min_time` flag.
Use `Benchmark::MinTime(double t)` to set the minimum time used to determine how long
to run the benchmark. This option overrides the `benchmark_min_time` flag.
If a benchmark measures time manually, use `Benchmark::MinRelAccuracy(double r)` to set
the required minimum relative accuracy used to determine how long to run the benchmark.
This option overrides the `benchmark_min_rel_accuracy` flag.
void BM_test(benchmark::State& state) {
... body ...
Expand Down Expand Up @@ -1190,11 +1194,19 @@ class BENCHMARK_EXPORT Benchmark {
// multiplier kRangeMultiplier will be used.
Benchmark* RangeMultiplier(int multiplier);

// Set the minimum amount of time to use when running this benchmark. This
// option overrides the `benchmark_min_time` flag.
// Set the minimum amount of time to use to determine the required number
// of iterations when running this benchmark. This option overrides
// the `benchmark_min_time` flag.
// REQUIRES: `t > 0` and `Iterations` has not been called on this benchmark.
Benchmark* MinTime(double t);

// Set the minimum relative accuracy to use to determine the required number
// of iterations when running this benchmark. This option overrides
// the `benchmark_min_rel_accuracy` flag.
// REQUIRES: `t > 0`, `Iterations` has not been called on this benchmark, and
// time is measured manually, i.e., `UseManualTime` has been called on this
// benchmark and each benchmark iteration should call SetIterationTime(seconds)
// to report the measured time.
Benchmark* MinRelAccuracy(double r);

// Set the minimum amount of time to run the benchmark before taking runtimes
Expand Down Expand Up @@ -1766,6 +1778,7 @@ class BENCHMARK_EXPORT BenchmarkReporter {
threads(1),
time_unit(GetDefaultTimeUnit()),
real_accumulated_time(0),
manual_accumulated_time_pow2(0),
cpu_accumulated_time(0),
max_heapbytes_used(0),
complexity(oNone),
Expand Down Expand Up @@ -1793,6 +1806,7 @@ class BENCHMARK_EXPORT BenchmarkReporter {
int64_t repetitions;
TimeUnit time_unit;
double real_accumulated_time;
double manual_accumulated_time_pow2;
double cpu_accumulated_time;

// Return a value representing the real time per iteration in the unit
Expand Down
25 changes: 20 additions & 5 deletions src/benchmark.cc
Original file line number Diff line number Diff line change
Expand Up @@ -65,11 +65,11 @@ BM_DEFINE_bool(benchmark_list_tests, false);
// linked into the binary are run.
BM_DEFINE_string(benchmark_filter, "");

// Specification of how long to run the benchmark.
// Specification of either an exact number of iterations (specified as `<integer>x`)
// or a minimum number of seconds (specified as `<float>s`) used to determine how
// long to run the benchmark.
//
// It can be either an exact number of iterations (specified as `<integer>x`),
// or a minimum number of seconds (specified as `<float>s`). If the latter
// format (ie., min seconds) is used, the system may run the benchmark longer
// If the latter format (ie., min seconds) is used, the system may run the benchmark longer
// until the results are considered significant.
//
// For backward compatibility, the `s` suffix may be omitted, in which case,
Expand All @@ -81,6 +81,18 @@ BM_DEFINE_string(benchmark_filter, "");
// benchmark execution, regardless of number of threads.
BM_DEFINE_string(benchmark_min_time, kDefaultMinTimeStr);

// Specification of required relative accuracy used to determine how
// long to run the benchmark.
//
// REQUIRES: time is measured manually.
//
// Manual timers provide per-iteration times. The relative accuracy is
// measured as the standard deviation of these per-iteration times divided by
// the mean and the square root of the number of iterations. The benchmark is
// run until the specified minimum time or number of iterations is reached
// and the measured relative accuracy meets the specified requirement.
BM_DEFINE_double(benchmark_min_rel_accuracy, 0.0);

// Minimum number of seconds a benchmark should be run before results should be
// taken into account. This e.g can be necessary for benchmarks of code which
// needs to fill some form of cache before performance is of interest.
Expand Down Expand Up @@ -694,6 +706,8 @@ void ParseCommandLineFlags(int* argc, char** argv) {
ParseStringFlag(argv[i], "benchmark_filter", &FLAGS_benchmark_filter) ||
ParseStringFlag(argv[i], "benchmark_min_time",
&FLAGS_benchmark_min_time) ||
ParseDoubleFlag(argv[i], "benchmark_min_rel_accuracy",
&FLAGS_benchmark_min_rel_accuracy) ||
ParseDoubleFlag(argv[i], "benchmark_min_warmup_time",
&FLAGS_benchmark_min_warmup_time) ||
ParseInt32Flag(argv[i], "benchmark_repetitions",
Expand Down Expand Up @@ -753,7 +767,8 @@ void PrintDefaultHelp() {
"benchmark"
" [--benchmark_list_tests={true|false}]\n"
" [--benchmark_filter=<regex>]\n"
" [--benchmark_min_time=`<integer>x` OR `<float>s` ]\n"
" [--benchmark_min_time=`<integer>x` OR `<float>s`]\n"
" [--benchmark_min_rel_accuracy=<min_rel_accuracy>]\n"
" [--benchmark_min_warmup_time=<min_warmup_time>]\n"
" [--benchmark_repetitions=<num_repetitions>]\n"
" [--benchmark_enable_random_interleaving={true|false}]\n"
Expand Down
1 change: 1 addition & 0 deletions src/benchmark_register.cc
Original file line number Diff line number Diff line change
Expand Up @@ -360,6 +360,7 @@ Benchmark* Benchmark::MinTime(double t) {
Benchmark* Benchmark::MinRelAccuracy(double r) {
BM_CHECK(r > 0.0);
BM_CHECK(iterations_ == 0);
BM_CHECK(use_manual_time_);
min_rel_accuracy_ = r;
return this;
}
Expand Down
23 changes: 13 additions & 10 deletions src/benchmark_runner.cc
Original file line number Diff line number Diff line change
Expand Up @@ -93,6 +93,7 @@ BenchmarkReporter::Run CreateRunReport(
if (!report.skipped) {
if (b.use_manual_time()) {
report.real_accumulated_time = results.manual_time_used;
report.manual_accumulated_time_pow2 = results.manual_time_used_pow2;
} else {
report.real_accumulated_time = results.real_time_used;
}
Expand Down Expand Up @@ -139,7 +140,7 @@ void RunInThread(const BenchmarkInstance* b, IterationCount iters,
results.cpu_time_used += timer.cpu_time_used();
results.real_time_used += timer.real_time_used();
results.manual_time_used += timer.manual_time_used();
results.manual_time_used2 += timer.manual_time_used2();
results.manual_time_used_pow2 += timer.manual_time_used_pow2();
results.complexity_n += st.complexity_length_n();
internal::Increment(&results.counters, st.counters);
}
Expand Down Expand Up @@ -225,8 +226,10 @@ BenchmarkRunner::BenchmarkRunner(
: b(b_),
reports_for_family(reports_for_family_),
parsed_benchtime_flag(ParseBenchMinTime(FLAGS_benchmark_min_time)),
min_time(ComputeMinTime(b_, parsed_benchtime_flag)),
min_rel_accuracy(b_min_rel_accuracy()),
min_time(ComputeMinTime(b, parsed_benchtime_flag)),
min_rel_accuracy(!IsZero(b.min_rel_accuracy())
? b.min_rel_accuracy()
: FLAGS_benchmark_min_rel_accuracy),
min_warmup_time((!IsZero(b.min_time()) && b.min_warmup_time() > 0.0)
? b.min_warmup_time()
: FLAGS_benchmark_min_warmup_time),
Expand Down Expand Up @@ -303,10 +306,10 @@ BenchmarkRunner::IterationResults BenchmarkRunner::DoNIterations() {

// Base decisions off of real time if requested by this benchmark.
i.seconds = i.results.cpu_time_used;
i.seconds2 = 0;
i.seconds_pow2 = 0;
if (b.use_manual_time()) {
i.seconds = i.results.manual_time_used;
i.seconds2 = i.results.manual_time_used2;
i.seconds_pow2 = i.results.manual_time_used_pow2;
} else if (b.use_real_time()) {
i.seconds = i.results.real_time_used;
}
Expand All @@ -333,8 +336,8 @@ IterationCount BenchmarkRunner::PredictNumItersNeeded(

// So what seems to be the sufficiently-large iteration count? Round up.
const IterationCount max_next_iters = static_cast<IterationCount>(
std::lround(std::max(multiplier * static_cast<double>(i.iters),
static_cast<double>(i.iters) + 1.0)));
std::llround(std::max(multiplier * static_cast<double>(i.iters),
static_cast<double>(i.iters) + 1.0)));
// But we do have *some* limits though..
const IterationCount next_iters = std::min(max_next_iters, kMaxIterations);

Expand Down Expand Up @@ -364,8 +367,8 @@ double BenchmarkRunner::GetMinTimeToApply() const {
return warmup_done ? min_time : min_warmup_time;
}

double GetRelAccuracy(const IterationResults& i) const {
return std::sqrt(i.seconds2 / i.iters - std::pow(i.seconds / i.iters, 2.)) / (i.seconds / i.iters) / sqrt(i.iters);
double BenchmarkRunner::GetRelAccuracy(const IterationResults& i) const {
return std::sqrt(i.seconds_pow2 / i.iters - std::pow(i.seconds / i.iters, 2.)) / (i.seconds / i.iters) / sqrt(i.iters);
}

bool BenchmarkRunner::HasSufficientTimeToApply(const IterationResults& i) const {
Expand All @@ -377,7 +380,7 @@ bool BenchmarkRunner::HasSufficientTimeToApply(const IterationResults& i) const
}

bool BenchmarkRunner::HasSufficientRelAccuracy(const IterationResults& i) const {
return (!IsZero(GetMinRelAccuracy()) && (GetRelAccuracy(i) <= GetMinRelAccuracy()));
return (IsZero(GetMinRelAccuracy()) || (GetRelAccuracy(i) <= GetMinRelAccuracy()));
}

void BenchmarkRunner::FinishWarmUp(const IterationCount& i) {
Expand Down
3 changes: 2 additions & 1 deletion src/benchmark_runner.h
Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@
namespace benchmark {

BM_DECLARE_string(benchmark_min_time);
BM_DECLARE_double(benchmark_min_rel_accuracy);
BM_DECLARE_double(benchmark_min_warmup_time);
BM_DECLARE_int32(benchmark_repetitions);
BM_DECLARE_bool(benchmark_report_aggregates_only);
Expand Down Expand Up @@ -113,7 +114,7 @@ class BenchmarkRunner {
internal::ThreadManager::Result results;
IterationCount iters;
double seconds;
double seconds2;
double seconds_pow2;
};
IterationResults DoNIterations();

Expand Down
2 changes: 1 addition & 1 deletion src/thread_manager.h
Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,7 @@ class ThreadManager {
double real_time_used = 0;
double cpu_time_used = 0;
double manual_time_used = 0;
double manual_time_used2 = 0;
double manual_time_used_pow2 = 0;
int64_t complexity_n = 0;
std::string report_label_;
std::string skip_message_;
Expand Down
9 changes: 4 additions & 5 deletions src/thread_timer.h
Original file line number Diff line number Diff line change
Expand Up @@ -40,7 +40,7 @@ class ThreadTimer {
// Called by each thread
void SetIterationTime(double seconds) {
manual_time_used_ += seconds;
manual_time_used2_ += std::pow(seconds, 2.);
manual_time_used_pow2_ += std::pow(seconds, 2.);
}

bool running() const { return running_; }
Expand All @@ -63,9 +63,9 @@ class ThreadTimer {
return manual_time_used_;
}

double manual_time_used2() const {
double manual_time_used_pow2() const {
BM_CHECK(!running_);
return manual_time_used2_;
return manual_time_used_pow2_;
}

private:
Expand All @@ -83,11 +83,10 @@ class ThreadTimer {

// Accumulated time so far (does not contain current slice if running_)
double real_time_used_ = 0;

double cpu_time_used_ = 0;
// Manually set iteration time. User sets this with SetIterationTime(seconds).
double manual_time_used_ = 0;
double manual_time_used2_ = 0;
double manual_time_used_pow2_ = 0;
};

} // namespace internal
Expand Down
3 changes: 3 additions & 0 deletions test/CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,9 @@ benchmark_add_test(NAME min_time_flag_time COMMAND benchmark_min_time_flag_time_
compile_benchmark_test(benchmark_min_time_flag_iters_test)
benchmark_add_test(NAME min_time_flag_iters COMMAND benchmark_min_time_flag_iters_test)

compile_benchmark_test(benchmark_min_rel_accuracy_flag_test)
benchmark_add_test(NAME min_rel_accuracy_flag_test COMMAND benchmark_min_rel_accuracy_flag_test)

add_filter_test(filter_simple "Foo" 3)
add_filter_test(filter_simple_negative "-Foo" 2)
add_filter_test(filter_suffix "BM_.*" 4)
Expand Down
88 changes: 88 additions & 0 deletions test/benchmark_min_rel_accuracy_flag_test.cc
Original file line number Diff line number Diff line change
@@ -0,0 +1,88 @@
#include <cassert>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <random>
#include <string>
#include <vector>

#include "benchmark/benchmark.h"

// Tests that if a benchmark measures time manually, we can specify the required relative accuracy with
// --benchmark_min_rel_accuracy=<min_rel_accuracy>.
namespace {

class TestReporter : public benchmark::ConsoleReporter {
public:
virtual bool ReportContext(const Context& context) BENCHMARK_OVERRIDE {
return ConsoleReporter::ReportContext(context);
};

virtual void ReportRuns(const std::vector<Run>& report) BENCHMARK_OVERRIDE {
assert(report.size() == 1);
iters_.push_back(report[0].iterations);
real_accumulated_times_.push_back(report[0].real_accumulated_time);
manual_accumulated_time_pow2s_.push_back(report[0].manual_accumulated_time_pow2);
ConsoleReporter::ReportRuns(report);
};

TestReporter() {}

virtual ~TestReporter() {}

const std::vector<benchmark::IterationCount>& GetIters() const {
return iters_;
}

const std::vector<double>& GetRealAccumulatedTimes() const {
return real_accumulated_times_;
}

const std::vector<double>& GetManualAccumulatedTimePow2s() const {
return manual_accumulated_time_pow2s_;
}

private:
std::vector<benchmark::IterationCount> iters_;
std::vector<double> real_accumulated_times_;
std::vector<double> manual_accumulated_time_pow2s_;
};

} // end namespace

static void BM_MyBench(benchmark::State& state) {
static std::mt19937 rd{std::random_device{}()};
static std::uniform_real_distribution<double> mrand(0, 1);

for (auto s : state) {
state.SetIterationTime(mrand(rd));
}
}
BENCHMARK(BM_MyBench)->UseManualTime();

int main(int argc, char** argv) {
// Make a fake argv and append the new --benchmark_min_rel_accuracy=<min_rel_accuracy> to it.
int fake_argc = argc + 2;
const char** fake_argv = new const char*[static_cast<size_t>(fake_argc)];
for (int i = 0; i < argc; ++i) fake_argv[i] = argv[i];
fake_argv[argc] = "--benchmark_min_time=10s";
fake_argv[argc + 1] = "--benchmark_min_rel_accuracy=0.01";

benchmark::Initialize(&fake_argc, const_cast<char**>(fake_argv));

TestReporter test_reporter;
const size_t returned_count =
benchmark::RunSpecifiedBenchmarks(&test_reporter, "BM_MyBench");
assert(returned_count == 1);

// Check the executed iters.
const benchmark::IterationCount iters = test_reporter.GetIters()[0];
const double real_accumulated_time = test_reporter.GetRealAccumulatedTimes()[0];
const double manual_accumulated_time_pow2 = test_reporter.GetManualAccumulatedTimePow2s()[0];

const double rel_accuracy = std::sqrt(manual_accumulated_time_pow2 / iters - std::pow(real_accumulated_time / iters, 2.)) / (real_accumulated_time / iters) / sqrt(iters);
assert(rel_accuracy <= 0.01);

delete[] fake_argv;
return 0;
}

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