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3d85343d65
* Rewrite complexity_test to use (hardcoded) manual time This test is fundamentally flaky, because it tried to read tea leafs, and is inherently misbehaving in CI environments, since there are unmitigated sources of noise. That being said, the computed Big-O also depends on the `--benchmark_min_time=` Fixes https://github.com/google/benchmark/issues/272 * Correctly compute Big-O for manual timings. Fixes #1758. * complexity_test: do more stuff in empty loop * Make all empty loops be a bit longer empty Looks like on windows, some of these tests still fail, i guess clock precision is too small.
93 lines
2.3 KiB
C++
93 lines
2.3 KiB
C++
#include <cstdarg>
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#undef NDEBUG
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#include "../src/commandlineflags.h"
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#include "../src/perf_counters.h"
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#include "benchmark/benchmark.h"
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#include "output_test.h"
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namespace benchmark {
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BM_DECLARE_string(benchmark_perf_counters);
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} // namespace benchmark
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static void BM_Simple(benchmark::State& state) {
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for (auto _ : state) {
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auto iterations = double(state.iterations()) * double(state.iterations());
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benchmark::DoNotOptimize(iterations);
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}
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}
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BENCHMARK(BM_Simple);
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ADD_CASES(TC_JSONOut, {{"\"name\": \"BM_Simple\",$"}});
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const int kIters = 1000000;
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void BM_WithoutPauseResume(benchmark::State& state) {
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int n = 0;
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for (auto _ : state) {
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for (auto i = 0; i < kIters; ++i) {
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n = 1 - n;
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benchmark::DoNotOptimize(n);
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}
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}
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}
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BENCHMARK(BM_WithoutPauseResume);
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ADD_CASES(TC_JSONOut, {{"\"name\": \"BM_WithoutPauseResume\",$"}});
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void BM_WithPauseResume(benchmark::State& state) {
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int m = 0, n = 0;
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for (auto _ : state) {
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for (auto i = 0; i < kIters; ++i) {
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n = 1 - n;
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benchmark::DoNotOptimize(n);
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}
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state.PauseTiming();
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for (auto j = 0; j < kIters; ++j) {
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m = 1 - m;
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benchmark::DoNotOptimize(m);
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}
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state.ResumeTiming();
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}
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}
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BENCHMARK(BM_WithPauseResume);
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ADD_CASES(TC_JSONOut, {{"\"name\": \"BM_WithPauseResume\",$"}});
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static void CheckSimple(Results const& e) {
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CHECK_COUNTER_VALUE(e, double, "CYCLES", GT, 0);
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}
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double withoutPauseResumeInstrCount = 0.0;
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double withPauseResumeInstrCount = 0.0;
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static void SaveInstrCountWithoutResume(Results const& e) {
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withoutPauseResumeInstrCount = e.GetAs<double>("INSTRUCTIONS");
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}
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static void SaveInstrCountWithResume(Results const& e) {
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withPauseResumeInstrCount = e.GetAs<double>("INSTRUCTIONS");
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}
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CHECK_BENCHMARK_RESULTS("BM_Simple", &CheckSimple);
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CHECK_BENCHMARK_RESULTS("BM_WithoutPauseResume", &SaveInstrCountWithoutResume);
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CHECK_BENCHMARK_RESULTS("BM_WithPauseResume", &SaveInstrCountWithResume);
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int main(int argc, char* argv[]) {
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if (!benchmark::internal::PerfCounters::kSupported) {
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return 0;
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}
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benchmark::FLAGS_benchmark_perf_counters = "CYCLES,INSTRUCTIONS";
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benchmark::internal::PerfCounters::Initialize();
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RunOutputTests(argc, argv);
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BM_CHECK_GT(withPauseResumeInstrCount, kIters);
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BM_CHECK_GT(withoutPauseResumeInstrCount, kIters);
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BM_CHECK_LT(withPauseResumeInstrCount, 1.5 * withoutPauseResumeInstrCount);
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}
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