Criterion is a micro-benchmarking library for modern C++.
- Convenient static registration macros for setting up benchmarks
- Parameterized benchmarks (e.g., vary input size)
- Statistical analysis across multiple runs
- Requires compiler support for
C++17or newer standard - Header-only library - single header file version available at
single_include/ - MIT License
Let's say we have this merge sort implementation that needs to be benchmarked.
template<typename RandomAccessIterator, typename Compare>
void merge_sort(RandomAccessIterator first, RandomAccessIterator last,
Compare compare, std::size_t size) {
if (size < 2) return;
auto middle = first + size / 2;
merge_sort(first, middle, compare, size / 2);
merge_sort(middle, last, compare, size - size/2);
std::inplace_merge(first, middle, last, compare);
}Include <criterion/criterion.hpp> and you're good to go.
- Use the
BENCHMARKmacro to declare a benchmark - Use
SETUP_BENCHMARKandTEARDOWN_BENCHMARKto perform setup and teardown tasks- These tasks are not part of the measurement
#include <criterion/criterion.hpp>
BENCHMARK(MergeSort)
{
SETUP_BENCHMARK(
const auto size = 100;
std::vector<int> vec(size, 0); // vector of size 100
)
// Code to be benchmarked
merge_sort(vec.begin(), vec.end(), std::less<int>(), size);
TEARDOWN_BENCHMARK(
vec.clear();
)
}
CRITERION_BENCHMARK_MAIN()
What if we want to run this benchmark on a variety of sizes?
- The
BENCHMARKmacro can take typed parameters - Use
GET_ARGUMENTS(n)to get the nth argument passed to the benchmark - For benchmarks that require arguments, use
INVOKE_BENCHMARK_FOR_EACHand provide arguments
#include <criterion/criterion.hpp>
BENCHMARK(MergeSort, std::size_t) // <- one parameter to be passed to the benchmark
{
SETUP_BENCHMARK(
const auto size = GET_ARGUMENT(0); // <- get the argument passed to the benchmark
std::vector<int> vec(size, 0);
)
// Code to be benchmarked
merge_sort(vec.begin(), vec.end(), std::less<int>(), size);
TEARDOWN_BENCHMARK(
vec.clear();
)
}
// Run the above benchmark for a number of inputs:
INVOKE_BENCHMARK_FOR_EACH(MergeSort,
("/10", 10),
("/100", 100),
("/1K", 1000),
("/10K", 10000),
("/100K", 100000)
)
CRITERION_BENCHMARK_MAIN()
Let's say we have the following struct and we need to create a std::shared_ptr to it.
struct Song {
std::string artist;
std::string title;
Song(const std::string& artist_, const std::string& title_) :
artist{ artist_ }, title{ title_ } {}
};Here are two implementations for constructing the std::shared_ptr:
// Functions to be tested
auto Create_With_New() {
return std::shared_ptr<Song>(new Song("Black Sabbath", "Paranoid"));
}
auto Create_With_MakeShared() {
return std::make_shared<Song>("Black Sabbath", "Paranoid");
}We can setup a single benchmark that takes a std::function<> and measures performance like below.
BENCHMARK(ConstructSharedPtr, std::function<std::shared_ptr<Song>()>)
{
SETUP_BENCHMARK(
auto test_function = GET_ARGUMENT(0);
)
// Code to be benchmarked
auto song_ptr = test_function();
}
INVOKE_BENCHMARK_FOR_EACH(ConstructSharedPtr,
("/new", Create_With_New),
("/make_shared", Create_With_MakeShared)
)
CRITERION_BENCHMARK_MAIN()
CRITERION_BENCHMARK_MAIN() provides a main function that:
- Handles command-line arguments,
- Runs the registered benchmarks
- Exports results to file if requested by user.
Here's the help/man generated by the main function:
foo@bar:~$ ./benchmarks -h
NAME
./benchmarks -- Run Criterion benchmarks
SYNOPSIS
./benchmarks
[-w,--warmup <number>]
[-l,--list] [--list_filtered <regex>] [-r,--run_filtered <regex>]
[-e,--export_results {csv,json,md,asciidoc} <filename>]
[-q,--quiet] [-h,--help]
DESCRIPTION
This microbenchmarking utility repeatedly executes a list of benchmarks,
statistically analyzing and reporting on the temporal behavior of the executed code.
The options are as follows:
-w,--warmup number
Number of warmup runs (at least 1) to execute before the benchmark (default=3)
-l,--list
Print the list of available benchmarks
--list_filtered regex
Print a filtered list of available benchmarks (based on user-provided regex)
-r,--run_filtered regex
Run a filtered list of available benchmarks (based on user-provided regex)
-e,--export_results format filename
Export benchmark results to file. The following are the supported formats.
csv Comma separated values (CSV) delimited text file
json JavaScript Object Notation (JSON) text file
md Markdown (md) text file
asciidoc AsciiDoc (asciidoc) text file
-q,--quiet
Run benchmarks quietly, suppressing activity indicators
-h,--help
Print this help message
Benchmarks can be exported to one of a number of formats: .csv, .json, .md, and .asciidoc.
Use --export_results (or -e) to export results to one of the supported formats.
foo@bar:~$ ./vector_sort -e json results.json -q # run quietly and export to JSON
foo@bar:~$ cat results.json
{
"benchmarks": [
{
"name": "VectorSort/100",
"warmup_runs": 2,
"iterations": 2857140,
"mean_execution_time": 168.70,
"fastest_execution_time": 73.00,
"slowest_execution_time": 88809.00,
"lowest_rsd_execution_time": 84.05,
"lowest_rsd_percentage": 3.29,
"lowest_rsd_index": 57278,
"average_iteration_performance": 5927600.84,
"fastest_iteration_performance": 13698630.14,
"slowest_iteration_performance": 11260.12
},
{
"name": "VectorSort/1000",
"warmup_runs": 2,
"iterations": 2254280,
"mean_execution_time": 1007.70,
"fastest_execution_time": 640.00,
"slowest_execution_time": 102530.00,
"lowest_rsd_execution_time": 647.45,
"lowest_rsd_percentage": 0.83,
"lowest_rsd_index": 14098,
"average_iteration_performance": 992355.48,
"fastest_iteration_performance": 1562500.00,
"slowest_iteration_performance": 9753.24
},
{
"name": "VectorSort/10000",
"warmup_runs": 2,
"iterations": 259320,
"mean_execution_time": 8833.26,
"fastest_execution_time": 6276.00,
"slowest_execution_time": 114548.00,
"lowest_rsd_execution_time": 8374.15,
"lowest_rsd_percentage": 0.11,
"lowest_rsd_index": 7905,
"average_iteration_performance": 113208.45,
"fastest_iteration_performance": 159337.16,
"slowest_iteration_performance": 8729.96
}
]
}cmake -Hall -Bbuild
cmake --build build
# run `merge_sort` sample
./build/samples/merge_sort/merge_sortpython3 utils/amalgamate/amalgamate.py -c single_include.json -s .Contributions are welcome, have a look at the CONTRIBUTING.md document for more information.
The project is available under the MIT license.
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