# Composable Kernel The Composable Kernel (CK) library provides a programming model for writing performance-critical kernels for machine learning workloads across multiple architectures (GPUs, CPUs, etc.). The CK library uses general purpose kernel languages, such as HIP C++. CK uses two concepts to achieve performance portability and code maintainability: * A tile-based programming model * Algorithm complexity reduction for complex machine learning (ML) operators. This uses an innovative technique called *Tensor Coordinate Transformation*. ![ALT](/docs/data/ck_component.png "CK Components") The current CK library is structured into four layers: * Templated Tile Operators * Templated Kernel and Invoker * Instantiated Kernel and Invoker * Client API ![ALT](/docs/data/ck_layer.png "CK Layers") ## General information To build our documentation locally, use the following code: ``` bash cd docs pip3 install -r sphinx/requirements.txt python3 -m sphinx -T -E -b html -d _build/doctrees -D language=en . _build/html ``` You can find a list of our developers and contributors on our [Contributors](/CONTRIBUTORS.md) page. ```note If you use CK, cite us as follows: * [Realizing Tensor Operators Using Coordinate Transformations and Tile Based Programming](???): This paper will be available on arXiv soon. * [CITATION.cff](/CITATION.cff) ``` CK is released under the **[MIT license](/LICENSE)**. ## Building CK We recommend building CK inside Docker containers, which include all necessary packages. Pre-built Docker images are available on [DockerHub](https://hub.docker.com/r/rocm/composable_kernel/tags). 1. To build a new Docker image, use the Dockerfile provided with the source code: ```bash DOCKER_BUILDKIT=1 docker build -t ck:latest -f Dockerfile . ``` 2. Launch the Docker container: ```bash docker run \ -it \ --privileged \ --group-add sudo \ -w /root/workspace \ -v ${PATH_TO_LOCAL_WORKSPACE}:/root/workspace \ ck:latest \ /bin/bash ``` 3. Clone CK source code from the GitHub repository and start the build: ```bash git clone https://github.com/ROCm/composable_kernel.git && \ cd composable_kernel && \ mkdir build && \ cd build ``` You must set the `GPU_TARGETS` macro to specify the GPU target architecture(s) you want to run CK on. You can specify single or multiple architectures. If you specify multiple architectures, use a semicolon between each; for example, `gfx908;gfx90a;gfx940`. ```bash cmake \ -D CMAKE_PREFIX_PATH=/opt/rocm \ -D CMAKE_CXX_COMPILER=/opt/rocm/bin/hipcc \ -D CMAKE_BUILD_TYPE=Release \ -D GPU_TARGETS="gfx908;gfx90a" \ .. ``` If you don't set `GPU_TARGETS` on the cmake command line, CK is built for all GPU targets supported by the current compiler (this may take a long time). 4. Build the entire CK library: ```bash make -j ``` 5. Install CK: ```bash make -j install ``` ## Optional post-install steps * Build examples and tests: ```bash make -j examples tests ``` * Build and run all examples and tests: ```bash make -j check ``` You can find instructions for running each individual example in [example](/example). * Build ckProfiler: ```bash make -j ckProfiler ``` You can find instructions for running ckProfiler in [profiler](/profiler). Note the `-j` option for building with multiple threads in parallel. This speeds up the build significantly. Depending on the number of CPU cores and the amount of RAM on your system, you may want to limit the number of threads. For example, if you have a 128-core CPU and 64 Gb of RAM. By default, `-j` launches one thread per CPU core, which can cause the build to run out of memory and crash. In such cases, you can reduce the number of threads to 32 by using `-j32`. Additional cmake flags can be used to significantly speed-up the build: * `INSTANCES_ONLY` (default is OFF) must be set to ON in order to build only the instances and library while skipping all tests, examples, and profiler. This is useful in cases when you plan to use CK as a dependency and don't plan to run any examples or tests. * `DTYPES` (default is not set) can be set to any subset of "fp64;fp32;fp16;fp8;bf16;int8" to build instances of select data types only. The main default data types are fp32 and fp16; you can safely skip other data types. * `DL_KERNELS` (default is OFF) must be set to ON in order to build instances, such as `gemm_dl` or `batched_gemm_multi_d_dl`. These instances are useful on architectures like the NAVI2x, as most other platforms have faster instances, such as `xdl` or `wmma`, available. ## Using sccache for building The default CK Docker images come with a pre-installed version of sccache, which supports clang being used as hip-compiler (" -x hip"). Using sccache can help reduce the time to re-build code from hours to 1-2 minutes. In order to invoke sccache, you need to run: ```bash sccache --start-server ``` then add the following flags to the cmake command line: ```bash -DCMAKE_CXX_COMPILER_LAUNCHER=sccache -DCMAKE_C_COMPILER_LAUNCHER=sccache ``` You may need to clean up the build folder and repeat the cmake and make steps in order to take advantage of the sccache during subsequent builds. ## Using CK as pre-built kernel library You can find instructions for using CK as a pre-built kernel library in [client_example](/client_example). ## Contributing to CK When you contribute to CK, make sure you run `clang-format` on all changed files. We highly recommend using git hooks that are managed by the `pre-commit` framework. To install hooks, run: ```bash sudo script/install_precommit.sh ``` With this approach, `pre-commit` adds the appropriate hooks to your local repository and automatically runs `clang-format` (and possibly additional checks) before any commit is created. If you need to uninstall hooks from the repository, you can do so by running the following command: ```bash script/uninstall_precommit.sh ``` If you need to temporarily disable pre-commit hooks, you can add the `--no-verify` option to the `git commit` command.