Easiest way to test for existence of cuda
We have some nightly build machines that have the cuda libraries installed, but which do not have a cuda-capable GPU installed. These machines are capable of building cuda-enabled programs, but they are not capable of running these programs.
In our automated nightly build process, our cmake scripts use the cmake command
find_package(CUDA)
to determine whether the cuda software is installed. This sets the cmake variable CUDA_FOUND on platforms that have cuda software installed. This is great and it works perfectly. When CUDA_FOUND is set, it is OK to build cuda-enabled programs. Even when the machine has no cuda-capable GPU.
But cuda-using test programs naturally fail on the non-GPU cuda machines, causing our nightly dashboards look "dirty". So I want cmake to avoid running those tests on such machines. But I still want to build the cuda software on those machines.
After getting a positive CUDA_FOUND result, I would like to test for the presence of an actual GPU, and then set a variable, say CUDA_GPU_FOUND , to reflect this.
What is the simplest way to get cmake to test for the presence of a cuda-capable gpu?
This needs to work on three platforms: Windows with MSVC, Mac, and Linux. (That's why we use cmake in the first place)
EDIT: There are a couple of good looking suggestions in the answers for how write a program to test for the presence of a GPU. What is still missing is the means of getting CMake to compile and run this program at configuration time. I suspect that the TRY_RUN command in CMake will be critical here, but unfortunately that command is nearly undocumented, and I cannot figure out how to make it work. This CMake part of the problem might be a much more difficult question. Perhaps I should have asked this as two separate questions...
The answer to this question consists of two parts:
For part 1, the gpu sniffing program, I started with the answer provided by fabrizioM because it is so compact. I quickly discovered that I needed many of the details found in unknown's answer to get it to work well. What I ended up with is the following C source file, which I named has_cuda_gpu.c :
#include <stdio.h>
#include <cuda_runtime.h>
int main() {
int deviceCount, device;
int gpuDeviceCount = 0;
struct cudaDeviceProp properties;
cudaError_t cudaResultCode = cudaGetDeviceCount(&deviceCount);
if (cudaResultCode != cudaSuccess)
deviceCount = 0;
/* machines with no GPUs can still report one emulation device */
for (device = 0; device < deviceCount; ++device) {
cudaGetDeviceProperties(&properties, device);
if (properties.major != 9999) /* 9999 means emulation only */
++gpuDeviceCount;
}
printf("%d GPU CUDA device(s) foundn", gpuDeviceCount);
/* don't just return the number of gpus, because other runtime cuda
errors can also yield non-zero return values */
if (gpuDeviceCount > 0)
return 0; /* success */
else
return 1; /* failure */
}
Notice that the return code is zero in the case where a cuda-enabled GPU is found. This is because on one of my has-cuda-but-no-GPU machines, this program generates a runtime error with non-zero exit code. So any non-zero exit code is interpreted as "cuda does not work on this machine".
You might ask why I don't use cuda emulation mode on non-GPU machines. It is because emulation mode is buggy. I only want to debug my code, and work around bugs in cuda GPU code. I don't have time to debug the emulator.
The second part of the problem is the cmake code to use this test program. After some struggle, I have figured it out. The following block is part of a larger CMakeLists.txt file:
find_package(CUDA)
if(CUDA_FOUND)
try_run(RUN_RESULT_VAR COMPILE_RESULT_VAR
${CMAKE_BINARY_DIR}
${CMAKE_CURRENT_SOURCE_DIR}/has_cuda_gpu.c
CMAKE_FLAGS
-DINCLUDE_DIRECTORIES:STRING=${CUDA_TOOLKIT_INCLUDE}
-DLINK_LIBRARIES:STRING=${CUDA_CUDART_LIBRARY}
COMPILE_OUTPUT_VARIABLE COMPILE_OUTPUT_VAR
RUN_OUTPUT_VARIABLE RUN_OUTPUT_VAR)
message("${RUN_OUTPUT_VAR}") # Display number of GPUs found
# COMPILE_RESULT_VAR is TRUE when compile succeeds
# RUN_RESULT_VAR is zero when a GPU is found
if(COMPILE_RESULT_VAR AND NOT RUN_RESULT_VAR)
set(CUDA_HAVE_GPU TRUE CACHE BOOL "Whether CUDA-capable GPU is present")
else()
set(CUDA_HAVE_GPU FALSE CACHE BOOL "Whether CUDA-capable GPU is present")
endif()
endif(CUDA_FOUND)
This sets a CUDA_HAVE_GPU boolean variable in cmake that can subsequently be used to trigger conditional operations.
It took me a long time to figure out that the include and link parameters need to go in the CMAKE_FLAGS stanza, and what the syntax should be. The try_run documentation is very light, but there is more information in the try_compile documentation, which is a closely related command. I still needed to scour the web for examples of try_compile and try_run before getting this to work.
Another tricky but important detail is the third argument to try_run , the "bindir". You should probably always set this to ${CMAKE_BINARY_DIR} . In particular, do not set it to ${CMAKE_CURRENT_BINARY_DIR} if you are in a subdirectory of your project. CMake expects to find the subdirectory CMakeFiles/CMakeTmp within bindir, and spews errors if that directory does not exist. Just use ${CMAKE_BINARY_DIR} , which is one location where those subdirectories seem to naturally reside.
Write a simple program like
#include<cuda.h>
int main (){
int deviceCount;
cudaError_t e = cudaGetDeviceCount(&deviceCount);
return e == cudaSuccess ? deviceCount : -1;
}
and check the return value.
I just wrote a pure Python script that does some of the things you seem to need (I took much of this from the pystream project). It's basically just a wrapper for some functions in the CUDA run time library (it uses ctypes). Look at the main() function to see example usage. Also, be aware that I just wrote it, so it's likely to contain bugs. Use with caution.
#!/bin/bash
import sys
import platform
import ctypes
"""
cudart.py: used to access pars of the CUDA runtime library.
Most of this code was lifted from the pystream project (it's BSD licensed):
http://code.google.com/p/pystream
Note that this is likely to only work with CUDA 2.3
To extend to other versions, you may need to edit the DeviceProp Class
"""
cudaSuccess = 0
errorDict = {
1: 'MissingConfigurationError',
2: 'MemoryAllocationError',
3: 'InitializationError',
4: 'LaunchFailureError',
5: 'PriorLaunchFailureError',
6: 'LaunchTimeoutError',
7: 'LaunchOutOfResourcesError',
8: 'InvalidDeviceFunctionError',
9: 'InvalidConfigurationError',
10: 'InvalidDeviceError',
11: 'InvalidValueError',
12: 'InvalidPitchValueError',
13: 'InvalidSymbolError',
14: 'MapBufferObjectFailedError',
15: 'UnmapBufferObjectFailedError',
16: 'InvalidHostPointerError',
17: 'InvalidDevicePointerError',
18: 'InvalidTextureError',
19: 'InvalidTextureBindingError',
20: 'InvalidChannelDescriptorError',
21: 'InvalidMemcpyDirectionError',
22: 'AddressOfConstantError',
23: 'TextureFetchFailedError',
24: 'TextureNotBoundError',
25: 'SynchronizationError',
26: 'InvalidFilterSettingError',
27: 'InvalidNormSettingError',
28: 'MixedDeviceExecutionError',
29: 'CudartUnloadingError',
30: 'UnknownError',
31: 'NotYetImplementedError',
32: 'MemoryValueTooLargeError',
33: 'InvalidResourceHandleError',
34: 'NotReadyError',
0x7f: 'StartupFailureError',
10000: 'ApiFailureBaseError'}
try:
if platform.system() == "Microsoft":
_libcudart = ctypes.windll.LoadLibrary('cudart.dll')
elif platform.system()=="Darwin":
_libcudart = ctypes.cdll.LoadLibrary('libcudart.dylib')
else:
_libcudart = ctypes.cdll.LoadLibrary('libcudart.so')
_libcudart_error = None
except OSError, e:
_libcudart_error = e
_libcudart = None
def _checkCudaStatus(status):
if status != cudaSuccess:
eClassString = errorDict[status]
# Get the class by name from the top level of this module
eClass = globals()[eClassString]
raise eClass()
def _checkDeviceNumber(device):
assert isinstance(device, int), "device number must be an int"
assert device >= 0, "device number must be greater than 0"
assert device < 2**8-1, "device number must be < 255"
# cudaDeviceProp
class DeviceProp(ctypes.Structure):
_fields_ = [
("name", 256*ctypes.c_char), # < ASCII string identifying device
("totalGlobalMem", ctypes.c_size_t), # < Global memory available on device in bytes
("sharedMemPerBlock", ctypes.c_size_t), # < Shared memory available per block in bytes
("regsPerBlock", ctypes.c_int), # < 32-bit registers available per block
("warpSize", ctypes.c_int), # < Warp size in threads
("memPitch", ctypes.c_size_t), # < Maximum pitch in bytes allowed by memory copies
("maxThreadsPerBlock", ctypes.c_int), # < Maximum number of threads per block
("maxThreadsDim", 3*ctypes.c_int), # < Maximum size of each dimension of a block
("maxGridSize", 3*ctypes.c_int), # < Maximum size of each dimension of a grid
("clockRate", ctypes.c_int), # < Clock frequency in kilohertz
("totalConstMem", ctypes.c_size_t), # < Constant memory available on device in bytes
("major", ctypes.c_int), # < Major compute capability
("minor", ctypes.c_int), # < Minor compute capability
("textureAlignment", ctypes.c_size_t), # < Alignment requirement for textures
("deviceOverlap", ctypes.c_int), # < Device can concurrently copy memory and execute a kernel
("multiProcessorCount", ctypes.c_int), # < Number of multiprocessors on device
("kernelExecTimeoutEnabled", ctypes.c_int), # < Specified whether there is a run time limit on kernels
("integrated", ctypes.c_int), # < Device is integrated as opposed to discrete
("canMapHostMemory", ctypes.c_int), # < Device can map host memory with cudaHostAlloc/cudaHostGetDevicePointer
("computeMode", ctypes.c_int), # < Compute mode (See ::cudaComputeMode)
("__cudaReserved", 36*ctypes.c_int),
]
def __str__(self):
return """NVidia GPU Specifications:
Name: %s
Total global mem: %i
Shared mem per block: %i
Registers per block: %i
Warp size: %i
Mem pitch: %i
Max threads per block: %i
Max treads dim: (%i, %i, %i)
Max grid size: (%i, %i, %i)
Total const mem: %i
Compute capability: %i.%i
Clock Rate (GHz): %f
Texture alignment: %i
""" % (self.name, self.totalGlobalMem, self.sharedMemPerBlock,
self.regsPerBlock, self.warpSize, self.memPitch,
self.maxThreadsPerBlock,
self.maxThreadsDim[0], self.maxThreadsDim[1], self.maxThreadsDim[2],
self.maxGridSize[0], self.maxGridSize[1], self.maxGridSize[2],
self.totalConstMem, self.major, self.minor,
float(self.clockRate)/1.0e6, self.textureAlignment)
def cudaGetDeviceCount():
if _libcudart is None: return 0
deviceCount = ctypes.c_int()
status = _libcudart.cudaGetDeviceCount(ctypes.byref(deviceCount))
_checkCudaStatus(status)
return deviceCount.value
def getDeviceProperties(device):
if _libcudart is None: return None
_checkDeviceNumber(device)
props = DeviceProp()
status = _libcudart.cudaGetDeviceProperties(ctypes.byref(props), device)
_checkCudaStatus(status)
return props
def getDriverVersion():
if _libcudart is None: return None
version = ctypes.c_int()
_libcudart.cudaDriverGetVersion(ctypes.byref(version))
v = "%d.%d" % (version.value//1000,
version.value%100)
return v
def getRuntimeVersion():
if _libcudart is None: return None
version = ctypes.c_int()
_libcudart.cudaRuntimeGetVersion(ctypes.byref(version))
v = "%d.%d" % (version.value//1000,
version.value%100)
return v
def getGpuCount():
count=0
for ii in range(cudaGetDeviceCount()):
props = getDeviceProperties(ii)
if props.major!=9999: count+=1
return count
def getLoadError():
return _libcudart_error
version = getDriverVersion()
if version is not None and not version.startswith('2.3'):
sys.stdout.write("WARNING: Driver version %s may not work with %sn" %
(version, sys.argv[0]))
version = getRuntimeVersion()
if version is not None and not version.startswith('2.3'):
sys.stdout.write("WARNING: Runtime version %s may not work with %sn" %
(version, sys.argv[0]))
def main():
sys.stdout.write("Driver version: %sn" % getDriverVersion())
sys.stdout.write("Runtime version: %sn" % getRuntimeVersion())
nn = cudaGetDeviceCount()
sys.stdout.write("Device count: %sn" % nn)
for ii in range(nn):
props = getDeviceProperties(ii)
sys.stdout.write("nDevice %d:n" % ii)
#sys.stdout.write("%s" % props)
for f_name, f_type in props._fields_:
attr = props.__getattribute__(f_name)
sys.stdout.write( " %s: %sn" % (f_name, attr))
gpuCount = getGpuCount()
if gpuCount > 0:
sys.stdout.write("n")
sys.stdout.write("GPU count: %dn" % getGpuCount())
e = getLoadError()
if e is not None:
sys.stdout.write("There was an error loading a library:n%snn" % e)
if __name__=="__main__":
main()
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