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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include <vespa/vespalib/util/clock.h>
#include <vespa/vespalib/util/invokeserviceimpl.h>
#include <cassert>
#include <vector>
#include <atomic>
#include <cinttypes>
#include <cstring>
#include <condition_variable>
#include <mutex>
#include <thread>
using vespalib::Clock;
using vespalib::steady_time;
using vespalib::steady_clock;
using vespalib::duration;
using vespalib::to_s;
struct UpdateClock {
virtual ~UpdateClock() {}
virtual void update() = 0;
};
struct NSValue : public UpdateClock {
void update() override { _value = std::chrono::steady_clock::now().time_since_epoch().count(); }
int64_t _value;
};
struct NSVolatile : public UpdateClock {
void update() override { _value = std::chrono::steady_clock::now().time_since_epoch().count(); }
volatile int64_t _value;
};
struct NSAtomic : public UpdateClock {
void update() override { _value.store(std::chrono::steady_clock::now().time_since_epoch().count()); }
std::atomic<int64_t> _value;
};
class TestClock
{
private:
int _timePeriodMS;
std::mutex _lock;
std::condition_variable _cond;
UpdateClock &_clock;
bool _stop;
std::thread _thread;
void run();
public:
TestClock(UpdateClock & clock, double timePeriod)
: _timePeriodMS(static_cast<uint32_t>(timePeriod*1000)),
_lock(),
_cond(),
_clock(clock),
_stop(false),
_thread()
{
_thread = std::thread([this](){run();});
}
~TestClock() {
{
std::lock_guard<std::mutex> guard(_lock);
_stop = true;
_cond.notify_all();
}
_thread.join();
}
};
void TestClock::run()
{
std::unique_lock<std::mutex> guard(_lock);
while (!_stop) {
_clock.update();
_cond.wait_for(guard, std::chrono::milliseconds(_timePeriodMS));
}
}
template<typename Func>
struct Sampler {
Sampler(Func func, uint64_t samples)
: _samples(samples),
_count(),
_func(func),
_thread()
{
memset(_count, 0, sizeof(_count));
_thread = std::thread([this](){run();});
}
void run() {
steady_time prev = _func();
for (uint64_t samples = 0; samples < _samples; ++samples) {
steady_time now = _func();
duration diff = now - prev;
if (diff > duration::zero()) prev = now;
_count[1 + ((diff == duration::zero()) ? 0 : (diff > duration::zero()) ? 1 : -1)]++;
}
}
uint64_t _samples;
uint64_t _count[3];
Func _func;
std::thread _thread;
};
template<typename Func>
void benchmark(const char * desc, uint64_t samples, uint32_t numThreads, Func func) {
std::vector<std::unique_ptr<Sampler<Func>>> threads;
threads.reserve(numThreads);
steady_time start = steady_clock::now();
for (uint32_t i(0); i < numThreads; i++) {
threads.push_back(std::make_unique<Sampler<Func>>(func, samples));
}
uint64_t count[3];
memset(count, 0, sizeof(count));
for (const auto & sampler : threads) {
sampler->_thread.join();
for (uint32_t i(0); i < 3; i++) {
count[i] += sampler->_count[i];
}
}
printf("%s: Took %" PRId64 " clock samples in %2.3f with [%" PRId64 ", %" PRId64 ", %" PRId64 "] counts\n", desc, samples, to_s(steady_clock::now() - start), count[0], count[1], count[2]);
}
int
main(int argc, char *argv[])
{
if (argc != 4) {
fprintf(stderr, "usage: %s <frequency> <numThreads> <samples>\n", argv[0]);
return 1;
}
uint64_t frequency = atoll(argv[1]);
uint32_t numThreads = atoi(argv[2]);
uint64_t samples = atoll(argv[3]);
NSValue nsValue;
NSVolatile nsVolatile;
NSAtomic nsAtomic;
vespalib::InvokeServiceImpl invoker(vespalib::from_s(1.0/frequency));
Clock clock(invoker.nowRef());
TestClock nsClock(nsValue, 1.0/frequency);
TestClock nsVolatileClock(nsVolatile, 1.0/frequency);
TestClock nsAtomicClock(nsAtomic, 1.0/frequency);
benchmark("vespalib::Clock", samples, numThreads, [&clock]() {
return clock.getTimeNS();
});
benchmark("uint64_t", samples, numThreads, [&nsValue]() {
return steady_time (duration(nsValue._value));
});
benchmark("volatile uint64_t", samples, numThreads, [&nsVolatile]() {
return steady_time(duration(nsVolatile._value));
});
benchmark("memory_order_relaxed", samples, numThreads, [&nsAtomic]() {
return steady_time(duration(nsAtomic._value.load(std::memory_order_relaxed)));
});
benchmark("memory_order_consume", samples, numThreads, [&nsAtomic]() {
return steady_time(duration(nsAtomic._value.load(std::memory_order_consume)));
});
benchmark("memory_order_acquire", samples, numThreads, [&nsAtomic]() {
return steady_time(duration(nsAtomic._value.load(std::memory_order_acquire)));
});
benchmark("memory_order_seq_cst", samples, numThreads, [&nsAtomic]() {
return steady_time(duration(nsAtomic._value.load(std::memory_order_seq_cst)));
});
benchmark("vespalib::steady_time::now()", samples, numThreads, []() {
return steady_clock::now();
});
return 0;
}
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