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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/testkit/test_kit.h>
#include "dummy.h"
#include <chrono>
class SpinLock {
private:
std::atomic_flag _lock;
public:
SpinLock() : _lock(false) {}
void lock() {
while (_lock.test_and_set(std::memory_order_acquire)) {
// spin
}
}
void unlock() { _lock.clear(std::memory_order_release); }
};
TEST("lock speed") {
using clock = std::chrono::steady_clock;
using ms_double = std::chrono::duration<double, std::milli>;
clock::time_point start;
ms_double ms;
DummyLock dummy;
std::mutex lock;
SpinLock spin;
double dummyTime;
double actualTime;
double overhead;
double spin_overhead;
double spin_factor;
uint32_t i;
start = clock::now();
for (i = 0; i < 1000000; i++) {
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
dummy.Lock();
dummy.Unlock();
}
ms = (clock::now() - start);
dummyTime = ms.count();
fprintf(stderr,
"10M dummy lock/unlock: %f ms (%1.2f/ms)\n",
dummyTime, 10000000.0 / dummyTime);
start = clock::now();
for (i = 0; i < 1000000; i++) {
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
lock.lock();
lock.unlock();
}
ms = (clock::now() - start);
actualTime = ms.count();
fprintf(stderr,
"10M actual lock/unlock: %f ms (%1.2f/ms)\n",
ms.count(), 10000000.0 / ms.count());
overhead = (actualTime - dummyTime) / 10000.0;
start = clock::now();
for (i = 0; i < 1000000; i++) {
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
spin.lock();
spin.unlock();
}
ms = (clock::now() - start);
actualTime = ms.count();
fprintf(stderr,
"10M actual (spin) lock/unlock: %f ms (%1.2f/ms)\n",
ms.count(), 10000000.0 / ms.count());
spin_overhead = (actualTime - dummyTime) / 10000.0;
spin_factor = overhead / spin_overhead;
fprintf(stderr,
"approx overhead per lock/unlock: %f microseconds\n",
overhead);
fprintf(stderr,
"approx overhead per lock/unlock (spin): %f microseconds\n",
spin_overhead);
fprintf(stderr,
"spinlocks are %f times faster\n",
spin_factor);
//---------------------------------------------------------------------------
start = clock::now();
for (i = 0; i < 1000000; i++) {
[[maybe_unused]] std::mutex lock0;
[[maybe_unused]] std::mutex lock1;
[[maybe_unused]] std::mutex lock2;
[[maybe_unused]] std::mutex lock3;
[[maybe_unused]] std::mutex lock4;
[[maybe_unused]] std::mutex lock5;
[[maybe_unused]] std::mutex lock6;
[[maybe_unused]] std::mutex lock7;
[[maybe_unused]] std::mutex lock8;
[[maybe_unused]] std::mutex lock9;
}
ms = (clock::now() - start);
fprintf(stderr, "10M mutex create/destroy %f ms (%1.2f/ms)\n",
ms.count(), 10000000.0 / ms.count());
//---------------------------------------------------------------------------
start = clock::now();
for (i = 0; i < 1000000; i++) {
std::condition_variable cond0;
std::condition_variable cond1;
std::condition_variable cond2;
std::condition_variable cond3;
std::condition_variable cond4;
std::condition_variable cond5;
std::condition_variable cond6;
std::condition_variable cond7;
std::condition_variable cond8;
std::condition_variable cond9;
}
ms = (clock::now() - start);
fprintf(stderr, "10M cond create/destroy %f ms (%1.2f/ms)\n",
ms.count(), 10000000.0 / ms.count());
//---------------------------------------------------------------------------
start = clock::now();
for (i = 0; i < 1000000; i++) {
DummyObj dummy0;
DummyObj dummy1;
DummyObj dummy2;
DummyObj dummy3;
DummyObj dummy4;
DummyObj dummy5;
DummyObj dummy6;
DummyObj dummy7;
DummyObj dummy8;
DummyObj dummy9;
}
ms = (clock::now() - start);
fprintf(stderr, "10M dummy create/destroy %f ms (%1.2f/ms)\n",
ms.count(), 10000000.0 / ms.count());
//---------------------------------------------------------------------------
start = clock::now();
for (i = 0; i < 1000000; i++) {
DummyObj *dummy0 = new DummyObj();
DummyObj *dummy1 = new DummyObj();
DummyObj *dummy2 = new DummyObj();
DummyObj *dummy3 = new DummyObj();
DummyObj *dummy4 = new DummyObj();
DummyObj *dummy5 = new DummyObj();
DummyObj *dummy6 = new DummyObj();
DummyObj *dummy7 = new DummyObj();
DummyObj *dummy8 = new DummyObj();
DummyObj *dummy9 = new DummyObj();
delete dummy9;
delete dummy8;
delete dummy7;
delete dummy6;
delete dummy5;
delete dummy4;
delete dummy3;
delete dummy2;
delete dummy1;
delete dummy0;
}
ms = (clock::now() - start);
fprintf(stderr, "10M dummy new/delete %f ms (%1.2f/ms)\n",
ms.count(), 10000000.0 / ms.count());
//---------------------------------------------------------------------------
}
TEST_MAIN() { TEST_RUN_ALL(); }
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