Performance tests for an encapsulation-enabled Data Oriented Design implementation
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cmake
results
.gitignore
CMakeLists.txt
README.md
compiler_flags.cmake
dod_perfv1.cpp
dod_perfv2.cpp
sources.cmake
variants.cmake

README.md

Instructions

The project contains a CMakeLists.txt file with portable build and run settings. Just run cmake with the generator and compiler you want to test with. All output files are written to a hierarchical results/[CPU-MODEL]/[SYSTEM]/[ENVIRONMENT-COMPILER]/[BUILD_TYPE] directory.

Targets

The script looks at the SOURCE_NAMES list defined in the sources.cmake file to figure out what .cpp files should be configured and built. For each source SOURCE specified there, a cmake executable target named SOURCE is generated. This target uses [PROJECT_ROOT_DIR]/[SOURCE].cpp as unique source for the executable. Also each one of this targets has its own assembly listings file, timing output file, etc.

A possible value for the SOURCE_NAMES list could be:

set(SOURCE_NAMES dod_perfv1 dod_perfv2)

Configure and build

Create a build/ directory for out-of-source build, then run cmake configure and build steps:

Manu @ cpp_dod_tests $ mkdir build && cd build
Manu @ cpp_dod_tests/build $ cmake .. -G "Visual Studio 14" -DCPU_MODEL="My CPU" -DCMAKE_BUILD_TYPE=Release
Manu @ cpp_dod_tests/build $ cmake --build .

The CPU_MODEL option is mandatory, CPU model information is used for results organization. Also note build type can be passed as configure option with CMAKE_BUILD_TYPE variable (Release by default).

To ensure timings are run using the correct build configuration, a workaround to the multi-configuration setup of Visual Studio generator was done. By default VS generator ignores CMAKE_BUILD_TYPE variable, the config is selected at build time through the IDE or by passing a --config option to the cmake build command. This makes impossible to know what build type will be used at cmake configuration time. Instead, the workaround wraps the build call by passing the value held by CMAKE_BUILD_TYPE. This way we can safely do configuration based on build type, also the code is configured and run in the same way regardless its using a VS generator or a makefiles generator (i.e. always passing build type through CMAKE_BUILD_TYPE variable at configure call).

Compiler flags can be specified in the compiler_clags.cmake file, using the following variables:

  • STD_FLAGS: C++ version and stdlib related flags.
  • OPT_FLAGS: Optimization flags.
  • DEBUG_FLAGS: Flags to control debug settings.
  • SIMD_FLAGS: SIMD related flags.
  • USER_FLAGS: Extra user defined flags.

The classification of different compiler flags into that variables is not mandatory, actually those flags are passed by the following target_compile_options() call:

target_compile_options(${target} PRIVATE ${STD_FLAGS} ${OPT_FLAGS} ${DEBUG_FLAGS} ${SIMD_FLAGS} ${USER_FLAGS})

So you can simply pass the flags you want through the USER_FLAGS variable for example.

Assembly listings

The cmake script includes a GENERATE_ASSEMBLY option that, in addition to building the example, generates an assembly listing file using the same build settings. Just enable it when invoking cmake:

Manu : cpp_dod_tests/build $ cmake .. -G "Visual Studio 14" -DGENERATE_ASSEMBLY=ON -DCPU_MODEL="..." ...

Run and log timings to a file

A set of custom targets named run_[TARGET_NAME] was added to run and store timings in an easy way. Results are written to a output_[TARGET_NAME].txt file in the results directory:

Manu @ cpp_dod_tests/build $ cmake --build . --target run_dod_perfv1 # Or "make run_dod_perfv1" when using makefiles generator

Finally a run_all target is provided to configure and run a set of specific variants (Visual Studio generator vs Unix Makefiles for MinGW GCC, Debug vs Release, etc) defined as a VARIANTS cmake list in the variants.cmake file. This makes running tests in multiple machines pretty straightforward:

Manu @ cpp_dod_tests/build $ cmake .. -G "Unix Makefiles" -DGENERATE_ASSEMBLY=ON -DCPU_MODEL="My CPU"
Manu @ cpp_dod_tests/build $ make run_all

Also there's a build_all target which does the same but without running the tests, only building them on all variants:

Manu @ cpp_dod_tests/build $ cmake .. -G "Unix Makefiles" -DGENERATE_ASSEMBLY=ON -DCPU_MODEL="My CPU"
Manu @ cpp_dod_tests/build $ make build_all