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[英]In Python using ctypes for passing pointer to struct pointer to C function
[英]Passing c struct to a function using ctypes
我正在尝试在不添加 pycuda 依赖项的情况下查询 CUDA 设备。 这是我到目前为止所得到的:
import ctypes
cudart = ctypes.cdll.LoadLibrary('libcudart.so')
numDevices = ctypes.c_int()
cudart.cudaGetDeviceCount(ctypes.byref(numDevices))
print 'There are', numDevices.value, 'devices.'
for x in xrange(numDevices.value):
properties = None # XXX What goes here?
cudart.cudaGetDeviceProperties(ctypes.byref(properties), x)
print properties
问题是我无法创建一个空结构来传递给 cudaGetDeviceProperties()。 我想做这样的事情:
properties = cudart.cudaDeviceProp
但这会引发此错误:
AttributeError: /usr/local/cuda/lib64/libcudart.so: undefined symbol: cudaDeviceProp
这是相关的CUDA 文档。
(编辑)
感谢@mhawke,我得到了这个工作。 对于其他想要这样做的人,我将为您省去自己输入课程的工作:
class CudaDeviceProp(ctypes.Structure):
_fields_ = [
('name', ctypes.c_char * 256),
('totalGlobalMem', ctypes.c_size_t),
('sharedMemPerBlock', ctypes.c_size_t),
('regsPerBlock', ctypes.c_int),
('warpSize', ctypes.c_int),
('memPitch', ctypes.c_size_t),
('maxThreadsPerBlock', ctypes.c_int),
('maxThreadsDim', ctypes.c_int * 3),
('maxGridSize', ctypes.c_int * 3),
('clockRate', ctypes.c_int),
('totalConstMem', ctypes.c_size_t),
('major', ctypes.c_int),
('minor', ctypes.c_int),
('textureAlignment', ctypes.c_size_t),
('texturePitchAlignment', ctypes.c_size_t),
('deviceOverlap', ctypes.c_int),
('multiProcessorCount', ctypes.c_int),
('kernelExecTimeoutEnabled', ctypes.c_int),
('integrated', ctypes.c_int),
('canMapHostMemory', ctypes.c_int),
('computeMode', ctypes.c_int),
('maxTexture1D', ctypes.c_int),
('maxTexture1DMipmap', ctypes.c_int),
('maxTexture1DLinear', ctypes.c_int),
('maxTexture2D', ctypes.c_int * 2),
('maxTexture2DMipmap', ctypes.c_int * 2),
('maxTexture2DLinear', ctypes.c_int * 3),
('maxTexture2DGather', ctypes.c_int * 2),
('maxTexture3D', ctypes.c_int * 3),
('maxTexture3DAlt', ctypes.c_int * 3),
('maxTextureCubemap', ctypes.c_int),
('maxTexture1DLayered', ctypes.c_int * 2),
('maxTexture2DLayered', ctypes.c_int * 3),
('maxTextureCubemapLayered', ctypes.c_int * 2),
('maxSurface1D', ctypes.c_int),
('maxSurface2D', ctypes.c_int * 2),
('maxSurface3D', ctypes.c_int * 3),
('maxSurface1DLayered', ctypes.c_int * 2),
('maxSurface2DLayered', ctypes.c_int * 3),
('maxSurfaceCubemap', ctypes.c_int),
('maxSurfaceCubemapLayered', ctypes.c_int * 2),
('surfaceAlignment', ctypes.c_size_t),
('concurrentKernels', ctypes.c_int),
('ECCEnabled', ctypes.c_int),
('pciBusID', ctypes.c_int),
('pciDeviceID', ctypes.c_int),
('pciDomainID', ctypes.c_int),
('tccDriver', ctypes.c_int),
('asyncEngineCount', ctypes.c_int),
('unifiedAddressing', ctypes.c_int),
('memoryClockRate', ctypes.c_int),
('memoryBusWidth', ctypes.c_int),
('l2CacheSize', ctypes.c_int),
('maxThreadsPerMultiProcessor', ctypes.c_int),
('streamPrioritiesSupported', ctypes.c_int),
('globalL1CacheSupported', ctypes.c_int),
('localL1CacheSupported', ctypes.c_int),
('sharedMemPerMultiprocessor', ctypes.c_size_t),
('regsPerMultiprocessor', ctypes.c_int),
('managedMemSupported', ctypes.c_int),
('isMultiGpuBoard', ctypes.c_int),
('multiGpuBoardGroupID', ctypes.c_int),
('singleToDoublePrecisionPerfRatio', ctypes.c_int),
('pageableMemoryAccess', ctypes.c_int),
('concurrentManagedAccess', ctypes.c_int),
]
您需要定义ctypes.Structure
的子类,用于指定cudaDeviceProp
结构中的所有字段。 然后您可以将结构的实例传递给函数。 请注意,您需要按正确顺序填写所有字段。 其中一些是数组,因此您需要正确声明它们。
import ctypes
class CudaDeviceProp(ctypes.Structure):
_fields_ = [('ECCEnabled', ctypes.c_int),
('asyncEngineCount', ctypes.c_int),
('canMapHostMemory', ctypes.c_int),
('clockRate', ctypes.c_int),
('computeMode', ctypes.c_int),
('concurrentKernels', ctypes.c_int),
...
('totalGlobalMem', ctypes.c_size_t),
('unifiedAddressing', ctypes.c_int),
('warpSize', ctypes.c_int)]
properties = CudaDeviceProp()
cudart.cudaGetDeviceProperties(ctypes.byref(properties), 0)
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