Fix copyright lines for Bits.h and move BitsBenchmark.cpp

[folly.git] / folly / lang / test / BitsBenchmark.cpp

diff --git a/folly/lang/test/BitsBenchmark.cpp b/folly/lang/test/BitsBenchmark.cpp
new file mode 100644 (file)
index 0000000..754cf00
--- /dev/null
+++ b/folly/lang/test/BitsBenchmark.cpp
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2016-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.
+ */
+
+// @author Tudor Bosman (tudorb@fb.com)
+
+#include <folly/lang/Bits.h>
+
+#include <folly/Benchmark.h>
+
+using namespace folly;
+
+BENCHMARK(nextPowTwoClz, iters) {
+  for (unsigned long i = 0; i < iters; ++i) {
+    auto x = folly::nextPowTwo(iters);
+    folly::doNotOptimizeAway(x);
+  }
+}
+
+BENCHMARK_DRAW_LINE();
+BENCHMARK(isPowTwo, iters) {
+  bool b;
+  for (unsigned long i = 0; i < iters; ++i) {
+    b = folly::isPowTwo(i);
+    folly::doNotOptimizeAway(b);
+  }
+}
+
+BENCHMARK_DRAW_LINE();
+BENCHMARK(reverse, iters) {
+  uint64_t b = 0;
+  for (unsigned long i = 0; i < iters; ++i) {
+    b = folly::bitReverse(i + b);
+    folly::doNotOptimizeAway(b);
+  }
+}
+
+int main(int argc, char** argv) {
+  gflags::ParseCommandLineFlags(&argc, &argv, true);
+  folly::runBenchmarks();
+  return 0;
+}
+
+/*
+Benchmarks run on dual Xeon X5650's @ 2.67GHz w/hyperthreading enabled
+  (12 physical cores, 12 MB cache, 72 GB RAM)
+
+============================================================================
+folly/test/BitsBenchmark.cpp                    relative  time/iter  iters/s
+============================================================================
+nextPowTwoClz                                                0.00fs  Infinity
+----------------------------------------------------------------------------
+isPowTwo                                                   731.61ps    1.37G
+----------------------------------------------------------------------------
+reverse                                                      4.84ns  206.58M
+============================================================================
+*/