Istvan Kiss
212 líneas
8.0 KiB
ReStructuredText
212 líneas
8.0 KiB
ReStructuredText
.. meta::
|
|
:description: This page lists frequently asked questions about HIP
|
|
:keywords: AMD, ROCm, HIP, FAQ, frequently asked questions
|
|
|
|
*******************************************************************************
|
|
Frequently asked questions
|
|
*******************************************************************************
|
|
|
|
This topic provides answers to frequently asked questions from new HIP users and
|
|
users familiar with NVIDIA CUDA.
|
|
|
|
HIP Support
|
|
===========
|
|
|
|
What hardware does HIP support?
|
|
-------------------------------
|
|
|
|
HIP supports AMD and NVIDIA GPUs. See
|
|
:ref:`prerequisites of the install guide<install_prerequisites>` for detailed
|
|
information.
|
|
|
|
What operating systems does HIP support?
|
|
----------------------------------------
|
|
|
|
Linux as well as Windows are supported by ROCm. The exact versions are listed in
|
|
the system requirements for :ref:`rocm-install-on-linux:supported_distributions`
|
|
and :ref:`rocm-install-on-windows:supported-skus-win`.
|
|
|
|
.. note::
|
|
Not all HIP runtime API functions are yet supported on Windows.
|
|
A note is added to those functions' documentation in the
|
|
:ref:`HIP runtime API reference<runtime_api_reference>`.
|
|
|
|
What libraries does HIP provide?
|
|
--------------------------------
|
|
|
|
HIP provides key math and AI libraries. See :doc:`rocm:reference/api-libraries`
|
|
for the full list.
|
|
|
|
What NVIDIA CUDA features does HIP support?
|
|
-------------------------------------------
|
|
|
|
The :doc:`NVIDIA CUDA runtime API supported by HIP<hipify:reference/tables/CUDA_Runtime_API_functions_supported_by_HIP>`
|
|
and :doc:`NVIDIA CUDA driver API supported by HIP<hipify:reference/tables/CUDA_Driver_API_functions_supported_by_HIP>`
|
|
pages describe which NVIDIA CUDA APIs are supported and what the equivalents are.
|
|
The :ref:`HIP runtime API reference<runtime_api_reference>` describes each API and
|
|
its limitations, if any, compared with the equivalent CUDA API.
|
|
|
|
The kernel language features are documented in the
|
|
:doc:`/how-to/hip_cpp_language_extensions` page.
|
|
|
|
Relation to other GPGPU frameworks
|
|
==================================
|
|
|
|
Is HIP a drop-in replacement for CUDA?
|
|
--------------------------------------
|
|
|
|
The `HIPIFY <https://github.com/ROCm/HIPIFY>`_ tools can automatically convert
|
|
almost all CUDA runtime code to HIP. Most device code needs no additional
|
|
conversion because HIP and CUDA have the same signatures for math and built-in
|
|
functions except for the name. HIP code provides similar performance as native
|
|
CUDA code on NVIDIA platforms, plus the benefits of being compilable for AMD
|
|
platforms.
|
|
|
|
Additional porting might be required to deal with architecture feature
|
|
queries or CUDA capabilities that HIP doesn't support.
|
|
|
|
To better understand the syntax differences, see :doc:`CUDA to HIP API Function Comparison <reference/api_syntax>`
|
|
or the :doc:`HIP porting guide <how-to/hip_porting_guide>`.
|
|
|
|
Can I install CUDA and ROCm on the same machine?
|
|
------------------------------------------------
|
|
|
|
Yes, but you require a compatible GPU to run the compiled code.
|
|
|
|
On NVIDIA platforms, can I mix HIP code with CUDA code?
|
|
-------------------------------------------------------
|
|
|
|
Yes. Most HIP types and data structures are ``typedef`` s to CUDA equivalents and
|
|
can be used interchangeably. This can be useful for iteratively porting CUDA code.
|
|
|
|
See :doc:`how-to/hip_porting_guide` for more details.
|
|
|
|
Can a HIP binary run on both AMD and NVIDIA platforms?
|
|
------------------------------------------------------
|
|
|
|
HIP is a source-portable language that can be compiled to run on AMD or NVIDIA
|
|
platforms. However, the HIP tools don't create a "fat binary" that can run on
|
|
both platforms.
|
|
|
|
Compiler related questions
|
|
==========================
|
|
|
|
hipcc detected my platform incorrectly. What should I do?
|
|
---------------------------------------------------------
|
|
|
|
The environment variable ``HIP_PLATFORM`` can be used to specify the platform
|
|
for which the code is going to be compiled with ``hipcc``. See the
|
|
:doc:`hipcc environment variables<hipcc:env>` for more information.
|
|
|
|
.. warning::
|
|
|
|
If you specify HIP_PLATFORM=NVIDIA with hipcc, you also need to pass ``-x cu``
|
|
to hipcc when compiling files with the ``.hip`` file extension. Otherwise,
|
|
nvcc will not recognize the ``.hip`` file extension and will fail with
|
|
``nvcc fatal : Don't know what to do with <file>.hip``.
|
|
|
|
How to use HIP-Clang to build HIP programs?
|
|
------------------------------------------------------
|
|
|
|
:doc:`hipcc <hipcc:index>` is a compiler driver. This means it is not a compiler
|
|
but calls the appropriate compilers and sets some options.
|
|
|
|
The underlying compilers are :doc:`amdclang++ <llvm-project:index>` or
|
|
`nvcc <https://docs.nvidia.com/cuda/cuda-compiler-driver-nvcc/index.html>`_,
|
|
depending on the platform, and can be called directly.
|
|
|
|
What is HIP-Clang?
|
|
------------------
|
|
|
|
HIP-Clang is a Clang/LLVM-based compiler used to compile HIP programs for AMD
|
|
platforms. The executable is named :doc:`amdclang++ <llvm-project:index>` on
|
|
Linux and ``clang++`` on Windows.
|
|
|
|
Can I link HIP device code with host code compiled with another compiler such as gcc, icc, or clang?
|
|
-----------------------------------------------------------------------------------------------------------
|
|
|
|
Yes. HIP generates object code that conforms to the GCC ABI, and links with libstdc++.
|
|
This means you can compile host code with the compiler of your choice and link the
|
|
generated host object code with device code.
|
|
|
|
Can HIP applications be compiled with a C compiler?
|
|
---------------------------------------------------
|
|
|
|
HIP is a C/C++ API that can be used with C compilers. However, this applies only
|
|
to the API itself. Device code and the syntax for calling kernels must be
|
|
compiled with a supported compiler like :doc:`hipcc <hipcc:index>`. The code
|
|
objects that are generated with ``hipcc`` can, however, be used with a C
|
|
compiler, as shown in the code examples below.
|
|
|
|
The following is the HIP device code, assumed to be saved in ``device.hip``:
|
|
|
|
.. code-block:: c++
|
|
|
|
#include <hip/hip_runtime.h>
|
|
|
|
__global__ void kernel(double* array, size_t size){
|
|
const int x = threadIdx.x + blockIdx.x * blockDim.x;
|
|
if(x < size){array[x] = x;}
|
|
};
|
|
|
|
extern "C"{
|
|
hipError_t callKernel(int blocks, int threadsPerBlock, double* array, size_t size){
|
|
kernel<<<blocks, threadsPerBlock, 0, hipStreamDefault>>>(array, size);
|
|
return hipGetLastError();
|
|
}
|
|
}
|
|
|
|
The following is the host code, written in C, saved in ``host.c``:
|
|
|
|
.. code-block:: c
|
|
|
|
#include <hip/hip_runtime_api.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
|
|
#define HIP_CHECK(c) { \
|
|
if (c != hipSuccess){ \
|
|
printf("HIP Error : %s", hipGetErrorString(c)); \
|
|
printf(" %s %d\n", __FILE__, __LINE__); \
|
|
exit(c); \
|
|
} \
|
|
}
|
|
|
|
// Forward declaration - the implementation needs to be compiled with
|
|
// a device compiler like hipcc or amdclang++
|
|
hipError_t callKernel(int blocks, int threadsPerBlock, double* array, size_t size);
|
|
|
|
int main(int argc, char** argv) {
|
|
int blocks = 1024;
|
|
int threadsPerBlock = 256;
|
|
size_t arraySize = blocks * threadsPerBlock;
|
|
double* d_array;
|
|
double* h_array;
|
|
h_array = (double*)malloc(arraySize * sizeof(double));
|
|
|
|
HIP_CHECK(hipMalloc((void**)&d_array, arraySize * sizeof(double)));
|
|
HIP_CHECK(callKernel(blocks, threadsPerBlock, d_array, arraySize));
|
|
HIP_CHECK(hipMemcpy(h_array, d_array, arraySize * sizeof(double), hipMemcpyDeviceToHost));
|
|
HIP_CHECK(hipFree(d_array));
|
|
|
|
free(h_array);
|
|
return 0;
|
|
}
|
|
|
|
These files are then compiled and linked using
|
|
|
|
.. code-block:: shell
|
|
|
|
hipcc -c device.hip
|
|
gcc host.c device.o $(hipconfig --cpp_config) -L/opt/rocm/lib -lamdhip64
|
|
|
|
assuming the default installation of ROCm in ``/opt/rocm``.
|
|
|
|
How to guard code specific to the host or the GPU?
|
|
--------------------------------------------------
|
|
|
|
The compiler defines the ``__HIP_DEVICE_COMPILE__`` macro only when compiling
|
|
device code.
|
|
|
|
Refer to the :doc:`how-to/hip_porting_guide` for more information.
|