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Modernization pass of cycleclock_test #960

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copybara-service merged 1 commit into from
Jul 19, 2026
+19 −12
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Modernization pass of cycleclock_test #960

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31 changes: 19 additions & 12 deletions gloop/base/cycleclock_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -30,15 +30,20 @@
#include "absl/log/check.h"
#include "absl/log/log.h"
#include "gloop/base/config.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"

#if !PORTABLE_BASE // TODO: Remove when benchmark.h is portable.
#include "benchmark/benchmark.h"
#endif // !PORTABLE_BASE

namespace {

using ::testing::DoubleNear;

// Note that the time returned by SteadyClockNanos() uses an
// arbitrary epoch, not necessarily the Unix epoch.
static int64_t SteadyClockNanos() {
int64_t SteadyClockNanos() {
return std::chrono::duration_cast<std::chrono::nanoseconds>(
std::chrono::steady_clock::now().time_since_epoch())
.count();
Expand All @@ -55,8 +60,8 @@ struct TimePair {
// time read at a moment close to the read of the cycle counter.
// This is accomplished by making several attempts and
// picking the one with the lowest latency.
static struct TimePair GetTimePair() {
struct TimePair best;
TimePair GetTimePair() {
TimePair best;
int64_t best_interval_ns = 1000 * 1000 * 1000;
for (int i = 0; i != 10; i++) {
int64_t start_ns = SteadyClockNanos();
Expand All @@ -73,26 +78,26 @@ static struct TimePair GetTimePair() {

TEST(CycleClockTest, Frequency) {
for (int i = 0; i != 10; i++) {
struct TimePair start = GetTimePair();
TimePair start = GetTimePair();
// Don't use absl::SleepFor() since it depends on CycleClock which could be
// broken.
std::this_thread::sleep_for(std::chrono::seconds(1));
struct TimePair end = GetTimePair();
TimePair end = GetTimePair();
double measured_frequency = static_cast<double>(end.cycles - start.cycles) *
1e9 / static_cast<double>(end.ns - start.ns);
double returned_frequency = CycleClock::Frequency();
LOG(INFO) << "measured_frequency " << measured_frequency
<< " returned_frequency " << returned_frequency << " ratio "
<< returned_frequency / measured_frequency;
VLOG(1) << "measured_frequency " << measured_frequency
<< " returned_frequency " << returned_frequency << " ratio "
<< returned_frequency / measured_frequency;
// Check that the measured frequency is within 1% of
// the nominal frequency reported.
EXPECT_LT(measured_frequency * 0.99, returned_frequency);
EXPECT_LT(returned_frequency, measured_frequency * 1.01);
EXPECT_THAT(returned_frequency,
DoubleNear(measured_frequency, measured_frequency * 0.01));
}
}

#if !PORTABLE_BASE // TODO: Remove when benchmark.h is portable.
static void BM_Now(benchmark::State& state) {
void BM_Now(benchmark::State& state) {
int64_t c = 0;
for (auto _ : state) {
c = CycleClock::Now();
Expand All @@ -102,7 +107,7 @@ static void BM_Now(benchmark::State& state) {
}
BENCHMARK(BM_Now);

static void BM_NowWithRegisterPresure(benchmark::State& state) {
void BM_NowWithRegisterPresure(benchmark::State& state) {
int64_t c = 0;
for (auto _ : state) {
intptr_t r0 = 0, r1 = 0, r2 = 0, r3 = 0, r4 = 0;
Expand Down Expand Up @@ -138,3 +143,5 @@ static void BM_NowWithRegisterPresure(benchmark::State& state) {
BENCHMARK(BM_NowWithRegisterPresure);

#endif

} // namespace
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