A library to benchmark code snippets, similar to unit tests. Example:
#include <benchmark/benchmark.h>
static void BM_SomeFunction(benchmark::State& state) {
// Perform setup here
for (auto _ : state) {
// This code gets timed
SomeFunction();
}
}
// Register the function as a benchmark
BENCHMARK(BM_SomeFunction);
// Run the benchmark
BENCHMARK_MAIN();To get started, see Requirements and Installation. See Usage for a full example and the User Guide for a more comprehensive feature overview.
It may also help to read the Google Test documentation as some of the structural aspects of the APIs are similar.
IRC channels:
- libera #benchmark
Additional Tooling Documentation
Assembly Testing Documentation
Building and installing Python bindings
The library can be used with C++03. However, it requires C++11 to build, including compiler and standard library support.
The following minimum versions are required to build the library:
- GCC 4.8
- Clang 3.4
- Visual Studio 14 2015
- Intel 2015 Update 1
See Platform-Specific Build Instructions.
This describes the installation process using cmake. As pre-requisites, you'll need git and cmake installed.
See dependencies.md for more details regarding supported versions of build tools.
# Check out the library.
$ git clone https://github.com/google/benchmark.git
# Go to the library root directory
$ cd benchmark
# Make a build directory to place the build output.
$ cmake -E make_directory "build"
# Generate build system files with cmake, and download any dependencies.
$ cmake -E chdir "build" cmake -DBENCHMARK_DOWNLOAD_DEPENDENCIES=on -DCMAKE_BUILD_TYPE=Release ../
# or, starting with CMake 3.13, use a simpler form:
# cmake -DCMAKE_BUILD_TYPE=Release -S . -B "build"
# Build the library.
$ cmake --build "build" --config ReleaseThis builds the benchmark and benchmark_main libraries and tests.
On a unix system, the build directory should now look something like this:
/benchmark
/build
/src
/libbenchmark.a
/libbenchmark_main.a
/test
...
Next, you can run the tests to check the build.
$ cmake -E chdir "build" ctest --build-config ReleaseIf you want to install the library globally, also run:
sudo cmake --build "build" --config Release --target install
Note that Google Benchmark requires Google Test to build and run the tests. This dependency can be provided two ways:
- Checkout the Google Test sources into
benchmark/googletest. - Otherwise, if
-DBENCHMARK_DOWNLOAD_DEPENDENCIES=ONis specified during configuration as above, the library will automatically download and build any required dependencies.
If you do not wish to build and run the tests, add -DBENCHMARK_ENABLE_GTEST_TESTS=OFF
to CMAKE_ARGS.
By default, benchmark builds as a debug library. You will see a warning in the
output when this is the case. To build it as a release library instead, add
-DCMAKE_BUILD_TYPE=Release when generating the build system files, as shown
above. The use of --config Release in build commands is needed to properly
support multi-configuration tools (like Visual Studio for example) and can be
skipped for other build systems (like Makefile).
To enable link-time optimisation, also add -DBENCHMARK_ENABLE_LTO=true when
generating the build system files.
If you are using gcc, you might need to set GCC_AR and GCC_RANLIB cmake
cache variables, if autodetection fails.
If you are using clang, you may need to set LLVMAR_EXECUTABLE,
LLVMNM_EXECUTABLE and LLVMRANLIB_EXECUTABLE cmake cache variables.
To enable sanitizer checks (eg., asan and tsan), add:
-DCMAKE_C_FLAGS="-g -O2 -fno-omit-frame-pointer -fsanitize=address -fsanitize=thread -fno-sanitize-recover=all"
-DCMAKE_CXX_FLAGS="-g -O2 -fno-omit-frame-pointer -fsanitize=address -fsanitize=thread -fno-sanitize-recover=all "
The main branch contains the latest stable version of the benchmarking library; the API of which can be considered largely stable, with source breaking changes being made only upon the release of a new major version.
Newer, experimental, features are implemented and tested on the
v2 branch. Users who wish
to use, test, and provide feedback on the new features are encouraged to try
this branch. However, this branch provides no stability guarantees and reserves
the right to change and break the API at any time.
Define a function that executes the code to measure, register it as a benchmark
function using the BENCHMARK macro, and ensure an appropriate main function
is available:
#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();To run the benchmark, compile and link against the benchmark library
(libbenchmark.a/.so). If you followed the build steps above, this library will
be under the build directory you created.
# Example on linux after running the build steps above. Assumes the
# `benchmark` and `build` directories are under the current directory.
$ g++ mybenchmark.cc -std=c++11 -isystem benchmark/include \
-Lbenchmark/build/src -lbenchmark -lpthread -o mybenchmarkAlternatively, link against the benchmark_main library and remove
BENCHMARK_MAIN(); above to get the same behavior.
The compiled executable will run all benchmarks by default. Pass the --help
flag for option information or see the User Guide.
If using CMake, it is recommended to link against the project-provided
benchmark::benchmark and benchmark::benchmark_main targets using
target_link_libraries.
It is possible to use find_package to import an installed version of the
library.
find_package(benchmark REQUIRED)Alternatively, add_subdirectory will incorporate the library directly in
to one's CMake project.
add_subdirectory(benchmark)Either way, link to the library as follows.
target_link_libraries(MyTarget benchmark::benchmark)
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