JunyiXie / GoogleBenchmark-CMake-Example

A working example of how to use Google Benchmark and CMake

GoogleBenchmark-CMake-Example

A working example of how to integrate the Google benchmark library with CMake and Visual Studio.

Background

Being familiar with C# benchmarking packages like BenchmarkDotNet, I was looking for a similar solution for C++ projects. I stumbled upon benchmark but couldn't find a decent example on how to get it working quickly with Visual Studio 2019. Ideally I'd like to be able to produce benchmark data under Windows and Linux.

Requirements

The following minimum versions are required to run this example:

• CMake 3.11
• Windows:
  • Visual Studio 2019 with the C++ workload OR Visual Studio 2019 Build Tools
• Linux:
  • GCC 4.8
  • Clang 3.4

Example

This example is based on a slightly modified version of the example used on the benchmark documentation:

#include <benchmark/benchmark.h>

static void BM_StringCreation(benchmark::State& state) {
  for (auto _ : state)
    std::string empty_string;
}
// Register the function as a benchmark
BENCHMARK(BM_StringCreation);

// Define another benchmark
static void BM_StringCopy(benchmark::State& state) {
  std::string x = "hello";
  for (auto _ : state)
    std::string copy(x);
}
BENCHMARK(BM_StringCopy);

BENCHMARK_MAIN();

Building

The benchmark application needs to be linked against the benchmark library to run. The build is configured to download the latest benchmark library using Git and compile it as a dependency.

The following steps should build the example using an out-of-source build folder.

Windows

Open a x64 Native Tools Command Prompt for VS 2019 and execute the following:

mkdir build && cd build
cmake ../src
msbuild Benchmarks.sln -p:Configuration=Release

Linux

Execute the following from a bash shell:

mkdir build && cd build
cmake ../src -DCMAKE_BUILD_TYPE=Release
make

Usage

To run the benchmark execute the following from the build folder:

Windows

StringBenchmarks\Release\StringBenchmarks.exe

Linux

StringBenchmarks/StringBenchmarks

For additional examples of arguments that can be passed to the test executables please refer to the benchmark documentation Running Benchmarks.

How it Works

The key to getting this to work is by making use of the CMake FetchContent module. This will download the origin/master from the benchmark repository on Github and build it as a dependency. To reduce the build complexity the flag BENCHMARK_ENABLE_TESTING is set to NO to prevent and extra build dependency against the Google Test library.

Resources

• Google Benchmark https://github.com/google/benchmark