{"id":20229112,"url":"https://github.com/dacap/visitlab","last_synced_at":"2026-05-29T20:31:38.958Z","repository":{"id":66589548,"uuid":"583752999","full_name":"dacap/visitlab","owner":"dacap","description":"Compare performance of std::visit vs 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visitlab\n\nThis benchmark compares [std::visit()](https://en.cppreference.com/w/cpp/utility/variant/visit)\nvs. using a switch-case of [std::variant::index()](https://en.cppreference.com/w/cpp/utility/variant/index)\nto do a specific task depending on the [std::variant](https://en.cppreference.com/w/cpp/utility/variant) type.\n\n## Benchmark\n\nIt looks like `std::visit()` is faster on Windows (msvc) \u0026 macOS\n(clang), and the switch-case is faster on Linux (gcc).\n\n### Local Run\n\nCompiler: `g++ (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0`\nFlags: `-O2 -g -DNDEBUG`\n\n```\n2023-05-09T16:19:06-03:00\nRunning ./visitlab\nRun on (24 X 5100 MHz CPU s)\nCPU Caches:\n  L1 Data 48 KiB (x12)\n  L1 Instruction 32 KiB (x12)\n  L2 Unified 1280 KiB (x12)\n  L3 Unified 30720 KiB (x1)\nLoad Average: 1.29, 0.96, 0.78\n***WARNING*** CPU scaling is enabled, the benchmark real time measurements may be noisy and will incur extra overhead.\n--------------------------------------------------------\nBenchmark              Time             CPU   Iterations\n--------------------------------------------------------\nBM_Visit             325 ns          325 ns      2188033\nBM_SwitchCase        317 ns          317 ns      2214635\n```\n\n### GitHub Actions\n\n**Windows** (MSVC 19.34.31944.0)\n\n```\n2023-05-09T19:38:58+00:00\nRunning D:\\a\\visitlab\\visitlab\\build\\visitlab.exe\nRun on (2 X 2594 MHz CPU s)\nCPU Caches:\n  L1 Data 32 KiB (x2)\n  L1 Instruction 32 KiB (x2)\n  L2 Unified 1024 KiB (x2)\n  L3 Unified 36608 KiB (x1)\n--------------------------------------------------------\nBenchmark              Time             CPU   Iterations\n--------------------------------------------------------\nBM_Visit            3418 ns         3376 ns       203636\nBM_SwitchCase       3493 ns         3516 ns       213333\n```\n\n**macOS** (AppleClang 14.0.0.14000029)\n\n```\n2023-05-09T19:35:03+00:00\nRunning build/visitlab\nRun on (3 X 3337 MHz CPU s)\nCPU Caches:\n  L1 Data 32 KiB\n  L1 Instruction 32 KiB\n  L2 Unified 256 KiB (x3)\n  L3 Unified 12288 KiB\nLoad Average: 19.07, 10.54, 4.42\n--------------------------------------------------------\nBenchmark              Time             CPU   Iterations\n--------------------------------------------------------\nBM_Visit            1601 ns         1599 ns       438069\nBM_SwitchCase       2474 ns         1666 ns       441081\n```\n\n**Linux** (g++ GNU 11.3.0)\n\n```\n2023-05-09T19:34:37+00:00\nRunning build/visitlab\nRun on (2 X 2593.91 MHz CPU s)\nCPU Caches:\n  L1 Data 32 KiB (x2)\n  L1 Instruction 32 KiB (x2)\n  L2 Unified 1024 KiB (x2)\n  L3 Unified 36608 KiB (x1)\nLoad Average: 1.21, 0.58, 0.23\n--------------------------------------------------------\nBenchmark              Time             CPU   Iterations\n--------------------------------------------------------\nBM_Visit             836 ns          836 ns       830642\nBM_SwitchCase        769 ns          769 ns       901695\n```\n\n## License\n\nThis is free and unencumbered software released into the public\ndomain. Read [LICENSE.txt](LICENSE.txt) for more information.\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fdacap%2Fvisitlab","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fdacap%2Fvisitlab","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fdacap%2Fvisitlab/lists"}