namespace folly {
-BenchmarkSuspender::NanosecondsSpent BenchmarkSuspender::nsSpent;
+std::chrono::high_resolution_clock::duration BenchmarkSuspender::timeSpent;
typedef function<detail::TimeIterPair(unsigned int)> BenchmarkFun;
static double runBenchmarkGetNSPerIteration(const BenchmarkFun& fun,
const double globalBaseline) {
+ using std::chrono::duration_cast;
+ using std::chrono::high_resolution_clock;
+ using std::chrono::microseconds;
+ using std::chrono::nanoseconds;
+ using std::chrono::seconds;
+
// They key here is accuracy; too low numbers means the accuracy was
// coarse. We up the ante until we get to at least minNanoseconds
// timings.
- static uint64_t resolutionInNs = 0;
- if (!resolutionInNs) {
- timespec ts;
- CHECK_EQ(0, clock_getres(CLOCK_REALTIME, &ts));
- CHECK_EQ(0, ts.tv_sec) << "Clock sucks.";
- CHECK_LT(0, ts.tv_nsec) << "Clock too fast for its own good.";
- CHECK_EQ(1, ts.tv_nsec) << "Clock too coarse, upgrade your kernel.";
- resolutionInNs = uint64_t(ts.tv_nsec);
- }
+ static_assert(
+ std::is_same<high_resolution_clock::duration, nanoseconds>::value,
+ "High resolution clock must be nanosecond resolution.");
// We choose a minimum minimum (sic) of 100,000 nanoseconds, but if
// the clock resolution is worse than that, it will be larger. In
// essence we're aiming at making the quantization noise 0.01%.
- static const auto minNanoseconds = max<uint64_t>(
- uint64_t(FLAGS_bm_min_usec) * 1000ULL,
- min<uint64_t>(resolutionInNs * 100000ULL, 1000000000ULL));
+ static const auto minNanoseconds = std::max<nanoseconds>(
+ nanoseconds(100000), microseconds(FLAGS_bm_min_usec));
// We do measurements in several epochs and take the minimum, to
// account for jitter.
static const unsigned int epochs = 1000;
// We establish a total time budget as we don't want a measurement
// to take too long. This will curtail the number of actual epochs.
- const uint64_t timeBudgetInNs = FLAGS_bm_max_secs * 1000000000ULL;
- timespec global;
- CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &global));
+ const auto timeBudget = seconds(FLAGS_bm_max_secs);
+ auto global = high_resolution_clock::now();
double epochResults[epochs] = { 0 };
size_t actualEpochs = 0;
}
// We got an accurate enough timing, done. But only save if
// smaller than the current result.
- epochResults[actualEpochs] = max(0.0, double(nsecsAndIter.first) /
- nsecsAndIter.second - globalBaseline);
+ auto nsecs = duration_cast<nanoseconds>(nsecsAndIter.first).count();
+ epochResults[actualEpochs] =
+ max(0.0, double(nsecs) / nsecsAndIter.second - globalBaseline);
// Done with the current epoch, we got a meaningful timing.
break;
}
- timespec now;
- CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &now));
- if (detail::timespecDiff(now, global) >= timeBudgetInNs) {
+ auto now = high_resolution_clock::now();
+ if (now - global >= timeBudget) {
// No more time budget available.
++actualEpochs;
break;
#include <folly/ScopeGuard.h>
#include <folly/Traits.h>
#include <folly/portability/GFlags.h>
-#include <folly/portability/Time.h>
#include <cassert>
-#include <ctime>
-#include <boost/function_types/function_arity.hpp>
+#include <chrono>
#include <functional>
-#include <glog/logging.h>
#include <limits>
#include <type_traits>
+#include <boost/function_types/function_arity.hpp>
+#include <glog/logging.h>
+
DECLARE_bool(benchmark);
namespace folly {
namespace detail {
-typedef std::pair<uint64_t, unsigned int> TimeIterPair;
+using TimeIterPair =
+ std::pair<std::chrono::high_resolution_clock::duration, unsigned int>;
/**
* Adds a benchmark wrapped in a std::function. Only used
const char* name,
std::function<TimeIterPair(unsigned int)>);
-/**
- * Takes the difference between two timespec values. end is assumed to
- * occur after start.
- */
-inline uint64_t timespecDiff(timespec end, timespec start) {
- if (end.tv_sec == start.tv_sec) {
- assert(end.tv_nsec >= start.tv_nsec);
- return uint64_t(end.tv_nsec - start.tv_nsec);
- }
- assert(end.tv_sec > start.tv_sec);
- auto diff = uint64_t(end.tv_sec - start.tv_sec);
- assert(diff < std::numeric_limits<uint64_t>::max() / 1000000000ULL);
- return diff * 1000000000ULL + end.tv_nsec - start.tv_nsec;
-}
-
-/**
- * Takes the difference between two sets of timespec values. The first
- * two come from a high-resolution clock whereas the other two come
- * from a low-resolution clock. The crux of the matter is that
- * high-res values may be bogus as documented in
- * http://linux.die.net/man/3/clock_gettime. The trouble is when the
- * running process migrates from one CPU to another, which is more
- * likely for long-running processes. Therefore we watch for high
- * differences between the two timings.
- *
- * This function is subject to further improvements.
- */
-inline uint64_t timespecDiff(timespec end, timespec start,
- timespec endCoarse, timespec startCoarse) {
- auto fine = timespecDiff(end, start);
- auto coarse = timespecDiff(endCoarse, startCoarse);
- if (coarse - fine >= 1000000) {
- // The fine time is in all likelihood bogus
- return coarse;
- }
- return fine;
-}
-
} // namespace detail
/**
* Supporting type for BENCHMARK_SUSPEND defined below.
*/
struct BenchmarkSuspender {
+ using Clock = std::chrono::high_resolution_clock;
+ using TimePoint = Clock::time_point;
+ using Duration = Clock::duration;
+
BenchmarkSuspender() {
- CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &start));
+ start = Clock::now();
}
BenchmarkSuspender(const BenchmarkSuspender &) = delete;
BenchmarkSuspender(BenchmarkSuspender && rhs) noexcept {
start = rhs.start;
- rhs.start = {0, 0};
+ rhs.start = {};
}
BenchmarkSuspender& operator=(const BenchmarkSuspender &) = delete;
BenchmarkSuspender& operator=(BenchmarkSuspender && rhs) {
- if (start.tv_nsec > 0 || start.tv_sec > 0) {
+ if (start != TimePoint{}) {
tally();
}
start = rhs.start;
- rhs.start = {0, 0};
+ rhs.start = {};
return *this;
}
~BenchmarkSuspender() {
- if (start.tv_nsec > 0 || start.tv_sec > 0) {
+ if (start != TimePoint{}) {
tally();
}
}
void dismiss() {
- assert(start.tv_nsec > 0 || start.tv_sec > 0);
+ assert(start != TimePoint{});
tally();
- start = {0, 0};
+ start = {};
}
void rehire() {
- assert(start.tv_nsec == 0 || start.tv_sec == 0);
- CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &start));
+ assert(start == TimePoint{});
+ start = Clock::now();
}
template <class F>
}
/**
- * Accumulates nanoseconds spent outside benchmark.
+ * Accumulates time spent outside benchmark.
*/
- typedef uint64_t NanosecondsSpent;
- static NanosecondsSpent nsSpent;
+ static Duration timeSpent;
-private:
+ private:
void tally() {
- timespec end;
- CHECK_EQ(0, clock_gettime(CLOCK_REALTIME, &end));
- nsSpent += detail::timespecDiff(end, start);
+ auto end = Clock::now();
+ timeSpent += end - start;
start = end;
}
- timespec start;
+ TimePoint start;
};
/**
>::type
addBenchmark(const char* file, const char* name, Lambda&& lambda) {
auto execute = [=](unsigned int times) {
- BenchmarkSuspender::nsSpent = 0;
- timespec start, end;
+ BenchmarkSuspender::timeSpent = {};
unsigned int niter;
// CORE MEASUREMENT STARTS
- auto const r1 = clock_gettime(CLOCK_REALTIME, &start);
+ auto start = std::chrono::high_resolution_clock::now();
niter = lambda(times);
- auto const r2 = clock_gettime(CLOCK_REALTIME, &end);
+ auto end = std::chrono::high_resolution_clock::now();
// CORE MEASUREMENT ENDS
- CHECK_EQ(0, r1);
- CHECK_EQ(0, r2);
-
return detail::TimeIterPair(
- detail::timespecDiff(end, start) - BenchmarkSuspender::nsSpent,
- niter);
+ (end - start) - BenchmarkSuspender::timeSpent, niter);
};
detail::addBenchmarkImpl(file, name,
computeTimeCost();
}
+ static uint64_t timespecDiff(timespec end, timespec start) {
+ if (end.tv_sec == start.tv_sec) {
+ assert(end.tv_nsec >= start.tv_nsec);
+ return uint64_t(end.tv_nsec - start.tv_nsec);
+ }
+ assert(end.tv_sec > start.tv_sec);
+ auto diff = uint64_t(end.tv_sec - start.tv_sec);
+ assert(diff < std::numeric_limits<uint64_t>::max() / 1000000000ULL);
+ return diff * 1000000000ULL + end.tv_nsec - start.tv_nsec;
+ }
+
void computeTimeCost() {
timespec start, end;
clock_gettime(CLOCK_REALTIME, &start);
clock_gettime(CLOCK_REALTIME, &tv);
}
clock_gettime(CLOCK_REALTIME, &end);
- time_cost_ = 2 * detail::timespecDiff(end, start) / iters_;
+ time_cost_ = 2 * timespecDiff(end, start) / iters_;
}
void producer() {
clock_gettime(CLOCK_REALTIME, &sleepstart);
do {
clock_gettime(CLOCK_REALTIME, &sleeptime);
- } while (detail::timespecDiff(sleeptime, sleepstart) < 1000000);
+ } while (timespecDiff(sleeptime, sleepstart) < 1000000);
timespec tv;
clock_gettime(CLOCK_REALTIME, &tv);
projects / folly.git / commitdiff