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- /*
- * Copyright 2014-present Facebook, Inc.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
- #include <algorithm>
- #include <atomic>
- #include <thread>
- #include <vector>
- #include <folly/Benchmark.h>
- #include <folly/gen/Base.h>
- #include <folly/gen/ParallelMap.h>
- #include <folly/portability/Unistd.h>
- using namespace folly::gen;
- DEFINE_int32(
- threads,
- std::max(1, (int32_t)sysconf(_SC_NPROCESSORS_CONF) / 2),
- "Num threads.");
- constexpr int kFib = 35; // unit of work
- size_t fib(int n) {
- return n <= 1 ? 1 : fib(n - 1) * fib(n - 2);
- }
- BENCHMARK(FibSumMap, n) {
- auto result = seq(1, (int)n) | map([](int) { return fib(kFib); }) | sum;
- folly::doNotOptimizeAway(result);
- }
- BENCHMARK_RELATIVE(FibSumPmap, n) {
- // Schedule more work: enough so that each worker thread does the
- // same amount as one FibSumMap.
- const size_t kNumThreads = FLAGS_threads;
- // clang-format off
- auto result =
- seq(1, (int)(n * kNumThreads))
- | pmap([](int) { return fib(kFib); }, kNumThreads)
- | sum;
- // clang-format on
- folly::doNotOptimizeAway(result);
- }
- BENCHMARK_RELATIVE(FibSumThreads, n) {
- // Schedule kNumThreads to execute the same code as FibSumMap.
- const size_t kNumThreads = FLAGS_threads;
- std::vector<std::thread> workers;
- workers.reserve(kNumThreads);
- auto fn = [n] {
- auto result = seq(1, (int)n) | map([](int) { return fib(kFib); }) | sum;
- folly::doNotOptimizeAway(result);
- };
- for (size_t i = 0; i < kNumThreads; i++) {
- workers.push_back(std::thread(fn));
- }
- for (auto& w : workers) {
- w.join();
- }
- }
- /*
- ============================================================================
- folly/gen/test/ParallelMapBenchmark.cpp relative time/iter iters/s
- ============================================================================
- FibSumMap 41.64ms 24.02
- FibSumPmap 98.38% 42.32ms 23.63
- FibSumThreads 94.48% 44.07ms 22.69
- ============================================================================
- real0m15.595s
- user2m47.100s
- sys0m0.016s
- */
- int main(int argc, char* argv[]) {
- gflags::ParseCommandLineFlags(&argc, &argv, true);
- folly::runBenchmarks();
- return 0;
- }
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