diff options
author | Jingyue Wu <jingyue@google.com> | 2016-01-30 23:48:47 +0000 |
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committer | Jingyue Wu <jingyue@google.com> | 2016-01-30 23:48:47 +0000 |
commit | e3e4ffd172061f69ababfd199e188388bf74c913 (patch) | |
tree | d93f541bf86f850583e50a97dd1b4e33365075fb /docs | |
parent | a2b61fb42824eea09a4e2bd69ee3a6f560bf174f (diff) |
[doc] improve the doc for CUDA
1. Mentioned that CUDA support works best with trunk.
2. Simplified the example by removing its dependency on the CUDA samples.
3. Explain the --cuda-gpu-arch flag.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@259307 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'docs')
-rw-r--r-- | docs/CompileCudaWithLLVM.rst | 38 |
1 files changed, 21 insertions, 17 deletions
diff --git a/docs/CompileCudaWithLLVM.rst b/docs/CompileCudaWithLLVM.rst index a981ffe1e8f..aeaf81db9fe 100644 --- a/docs/CompileCudaWithLLVM.rst +++ b/docs/CompileCudaWithLLVM.rst @@ -18,9 +18,11 @@ familiarity with CUDA. Information about CUDA programming can be found in the How to Build LLVM with CUDA Support =================================== -Below is a quick summary of downloading and building LLVM. Consult the `Getting -Started <http://llvm.org/docs/GettingStarted.html>`_ page for more details on -setting up LLVM. +CUDA support is still in development and works the best in the trunk version +of LLVM. Below is a quick summary of downloading and building the trunk +version. Consult the `Getting Started +<http://llvm.org/docs/GettingStarted.html>`_ page for more details on setting +up LLVM. #. Checkout LLVM @@ -60,8 +62,6 @@ which multiplies a ``float`` array by a ``float`` scalar (AXPY). .. code-block:: c++ - #include <helper_cuda.h> // for checkCudaErrors - #include <iostream> __global__ void axpy(float a, float* x, float* y) { @@ -78,25 +78,25 @@ which multiplies a ``float`` array by a ``float`` scalar (AXPY). // Copy input data to device. float* device_x; float* device_y; - checkCudaErrors(cudaMalloc(&device_x, kDataLen * sizeof(float))); - checkCudaErrors(cudaMalloc(&device_y, kDataLen * sizeof(float))); - checkCudaErrors(cudaMemcpy(device_x, host_x, kDataLen * sizeof(float), - cudaMemcpyHostToDevice)); + cudaMalloc(&device_x, kDataLen * sizeof(float)); + cudaMalloc(&device_y, kDataLen * sizeof(float)); + cudaMemcpy(device_x, host_x, kDataLen * sizeof(float), + cudaMemcpyHostToDevice); // Launch the kernel. axpy<<<1, kDataLen>>>(a, device_x, device_y); // Copy output data to host. - checkCudaErrors(cudaDeviceSynchronize()); - checkCudaErrors(cudaMemcpy(host_y, device_y, kDataLen * sizeof(float), - cudaMemcpyDeviceToHost)); + cudaDeviceSynchronize(); + cudaMemcpy(host_y, device_y, kDataLen * sizeof(float), + cudaMemcpyDeviceToHost); // Print the results. for (int i = 0; i < kDataLen; ++i) { std::cout << "y[" << i << "] = " << host_y[i] << "\n"; } - checkCudaErrors(cudaDeviceReset()); + cudaDeviceReset(); return 0; } @@ -104,16 +104,20 @@ The command line for compilation is similar to what you would use for C++. .. code-block:: console - $ clang++ -o axpy -I<CUDA install path>/samples/common/inc -L<CUDA install path>/<lib64 or lib> axpy.cu -lcudart_static -lcuda -ldl -lrt -pthread + $ clang++ axpy.cu -o axpy --cuda-gpu-arch=<GPU arch> \ + -L<CUDA install path>/<lib64 or lib> \ + -lcudart_static -ldl -lrt -pthread $ ./axpy y[0] = 2 y[1] = 4 y[2] = 6 y[3] = 8 -Note that ``helper_cuda.h`` comes from the CUDA samples, so you need the -samples installed for this example. ``<CUDA install path>`` is the root -directory where you installed CUDA SDK, typically ``/usr/local/cuda``. +``<CUDA install path>`` is the root directory where you installed CUDA SDK, +typically ``/usr/local/cuda``. ``<GPU arch>`` is `the compute capability of +your GPU <https://developer.nvidia.com/cuda-gpus>`_. For example, if you want +to run your program on a GPU with compute capability of 3.5, you should specify +``--cuda-gpu-arch=sm_35``. Optimizations ============= |