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 `_ 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 +`_ 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 // for checkCudaErrors - #include __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/samples/common/inc -L/ axpy.cu -lcudart_static -lcuda -ldl -lrt -pthread + $ clang++ axpy.cu -o axpy --cuda-gpu-arch= \ + -L/ \ + -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. ```` is the root -directory where you installed CUDA SDK, typically ``/usr/local/cuda``. +```` is the root directory where you installed CUDA SDK, +typically ``/usr/local/cuda``. ```` is `the compute capability of +your GPU `_. 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 =============