mirror of
https://github.com/DrKLO/Telegram.git
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223 lines
6.4 KiB
C++
223 lines
6.4 KiB
C++
// Copyright 2017 The Abseil Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// https://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <cstdint>
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#include <mutex> // NOLINT(build/c++11)
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#include <vector>
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#include "absl/base/internal/cycleclock.h"
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#include "absl/base/internal/spinlock.h"
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#include "absl/synchronization/blocking_counter.h"
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#include "absl/synchronization/internal/thread_pool.h"
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#include "absl/synchronization/mutex.h"
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#include "benchmark/benchmark.h"
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namespace {
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void BM_Mutex(benchmark::State& state) {
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static absl::Mutex* mu = new absl::Mutex;
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for (auto _ : state) {
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absl::MutexLock lock(mu);
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}
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}
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BENCHMARK(BM_Mutex)->UseRealTime()->Threads(1)->ThreadPerCpu();
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static void DelayNs(int64_t ns, int* data) {
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int64_t end = absl::base_internal::CycleClock::Now() +
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ns * absl::base_internal::CycleClock::Frequency() / 1e9;
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while (absl::base_internal::CycleClock::Now() < end) {
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++(*data);
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benchmark::DoNotOptimize(*data);
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}
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}
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template <typename MutexType>
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class RaiiLocker {
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public:
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explicit RaiiLocker(MutexType* mu) : mu_(mu) { mu_->Lock(); }
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~RaiiLocker() { mu_->Unlock(); }
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private:
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MutexType* mu_;
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};
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template <>
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class RaiiLocker<std::mutex> {
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public:
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explicit RaiiLocker(std::mutex* mu) : mu_(mu) { mu_->lock(); }
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~RaiiLocker() { mu_->unlock(); }
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private:
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std::mutex* mu_;
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};
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template <typename MutexType>
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void BM_Contended(benchmark::State& state) {
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struct Shared {
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MutexType mu;
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int data = 0;
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};
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static auto* shared = new Shared;
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int local = 0;
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for (auto _ : state) {
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// Here we model both local work outside of the critical section as well as
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// some work inside of the critical section. The idea is to capture some
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// more or less realisitic contention levels.
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// If contention is too low, the benchmark won't measure anything useful.
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// If contention is unrealistically high, the benchmark will favor
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// bad mutex implementations that block and otherwise distract threads
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// from the mutex and shared state for as much as possible.
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// To achieve this amount of local work is multiplied by number of threads
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// to keep ratio between local work and critical section approximately
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// equal regardless of number of threads.
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DelayNs(100 * state.threads, &local);
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RaiiLocker<MutexType> locker(&shared->mu);
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DelayNs(state.range(0), &shared->data);
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}
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}
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BENCHMARK_TEMPLATE(BM_Contended, absl::Mutex)
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->UseRealTime()
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// ThreadPerCpu poorly handles non-power-of-two CPU counts.
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->Threads(1)
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->Threads(2)
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->Threads(4)
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->Threads(6)
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->Threads(8)
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->Threads(12)
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->Threads(16)
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->Threads(24)
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->Threads(32)
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->Threads(48)
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->Threads(64)
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->Threads(96)
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->Threads(128)
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->Threads(192)
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->Threads(256)
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// Some empirically chosen amounts of work in critical section.
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// 1 is low contention, 200 is high contention and few values in between.
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->Arg(1)
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->Arg(20)
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->Arg(50)
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->Arg(200);
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BENCHMARK_TEMPLATE(BM_Contended, absl::base_internal::SpinLock)
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->UseRealTime()
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// ThreadPerCpu poorly handles non-power-of-two CPU counts.
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->Threads(1)
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->Threads(2)
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->Threads(4)
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->Threads(6)
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->Threads(8)
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->Threads(12)
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->Threads(16)
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->Threads(24)
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->Threads(32)
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->Threads(48)
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->Threads(64)
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->Threads(96)
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->Threads(128)
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->Threads(192)
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->Threads(256)
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// Some empirically chosen amounts of work in critical section.
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// 1 is low contention, 200 is high contention and few values in between.
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->Arg(1)
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->Arg(20)
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->Arg(50)
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->Arg(200);
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BENCHMARK_TEMPLATE(BM_Contended, std::mutex)
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->UseRealTime()
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// ThreadPerCpu poorly handles non-power-of-two CPU counts.
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->Threads(1)
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->Threads(2)
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->Threads(4)
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->Threads(6)
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->Threads(8)
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->Threads(12)
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->Threads(16)
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->Threads(24)
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->Threads(32)
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->Threads(48)
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->Threads(64)
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->Threads(96)
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->Threads(128)
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->Threads(192)
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->Threads(256)
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// Some empirically chosen amounts of work in critical section.
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// 1 is low contention, 200 is high contention and few values in between.
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->Arg(1)
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->Arg(20)
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->Arg(50)
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->Arg(200);
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// Measure the overhead of conditions on mutex release (when they must be
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// evaluated). Mutex has (some) support for equivalence classes allowing
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// Conditions with the same function/argument to potentially not be multiply
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// evaluated.
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//
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// num_classes==0 is used for the special case of every waiter being distinct.
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void BM_ConditionWaiters(benchmark::State& state) {
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int num_classes = state.range(0);
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int num_waiters = state.range(1);
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struct Helper {
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static void Waiter(absl::BlockingCounter* init, absl::Mutex* m, int* p) {
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init->DecrementCount();
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m->LockWhen(absl::Condition(
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static_cast<bool (*)(int*)>([](int* v) { return *v == 0; }), p));
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m->Unlock();
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}
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};
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if (num_classes == 0) {
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// No equivalence classes.
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num_classes = num_waiters;
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}
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absl::BlockingCounter init(num_waiters);
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absl::Mutex mu;
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std::vector<int> equivalence_classes(num_classes, 1);
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// Must be declared last to be destroyed first.
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absl::synchronization_internal::ThreadPool pool(num_waiters);
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for (int i = 0; i < num_waiters; i++) {
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// Mutex considers Conditions with the same function and argument
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// to be equivalent.
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pool.Schedule([&, i] {
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Helper::Waiter(&init, &mu, &equivalence_classes[i % num_classes]);
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});
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}
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init.Wait();
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for (auto _ : state) {
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mu.Lock();
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mu.Unlock(); // Each unlock requires Condition evaluation for our waiters.
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}
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mu.Lock();
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for (int i = 0; i < num_classes; i++) {
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equivalence_classes[i] = 0;
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}
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mu.Unlock();
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}
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// Some configurations have higher thread limits than others.
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#if defined(__linux__) && !defined(THREAD_SANITIZER)
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constexpr int kMaxConditionWaiters = 8192;
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#else
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constexpr int kMaxConditionWaiters = 1024;
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#endif
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BENCHMARK(BM_ConditionWaiters)->RangePair(0, 2, 1, kMaxConditionWaiters);
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} // namespace
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