Thanks Andreas,
If I switch out the line "cuda.memcpy_dtoh(y,Y_gpu)" and replace it with
something else - either another memory copy or a synchronize option like
pycuda.autoinit.context.synchronize(). The same also happens if I get
rid of explicit memory copies and use the In(), Out() and InOut()
methods. If I don't execute the kernel then the memory copies work
without errors. So something in the kernel is causing an error, but this
is one of the example kernels from nvidia! Can you see anything wrong
with it? Does it execute on anyone elses machine?
# CUDA grid
block_size=(4,1,1)
grid = (n/block_size[0],1)
# CUDA source
cusrc = SourceModule("""
__global__ void saxpy(int n, double a, double *x, double *y)
{
for (int i = blockIdx.x * blockDim.x + threadIdx.x;
i < n;
i += blockDim.x * gridDim.x)
{
y[i] = a * x[i] + y[i];
}
}
""")
SAXPY = cusrc.get_function('saxpy')
# data arrays
w = 500 #arbitrary
x = random.uniform(0,w,n) #.astype(float32) << same error with
either float or double
y = random.uniform(0,w,n) #.astype(float32)
#init gpu (input) arrays
a = float64(24.5)
n = int32(n)
SAXPY(cuda.In(n), cuda.In(a), cuda.In(x), cuda.InOut(y), grid=grid,
block=block_size)
...
___ error message ____
Traceback (most recent call last):
File ".\as_cuda_loop.py", line 61, in <module>
main()
File ".\as_cuda_loop.py", line 46, in main
SAXPY(cuda.In(n), cuda.In(a), cuda.In(x), cuda.InOut(y), grid=grid,
block=block_size)
File
"c:\users\james\appdata\local\enthought\canopy\user\lib\site-packages\pycuda\driver.py",
line 377, in function_ca
ll
Context.synchronize()
pycuda._driver.LogicError: cuCtxSynchronize failed: invalid/unknown
error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuModuleUnload failed: invalid/unknown error code
Best regards
James
On 31/07/2014 01:16, Andreas Kloeckner wrote:
Hi James,
James Keaveney <[email protected]> writes:
I'm having an issue with PyCUDA that at first glance seem like they
might be similar to those of Thomas Unterthiner (messages from Jun 20
2014, "Weird bug when slicing arrays on Kepler cards"). I'm also using a
Kepler card (GTX 670) and getting the same clean-up/dead context errors.
However, unlike Thomas, I'm not using cublas. The simplest example I can
show is below, which is a cuda kernel taken directly from here:
http://devblogs.nvidia.com/parallelforall/cuda-pro-tip-write-flexible-kernels-grid-stride-loops/
[snip]
pycuda._driver.LogicError: cuMemcpyDtoH failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuModuleUnload failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
PyCUDA WARNING: a clean-up operation failed (dead context maybe?)
cuMemFree failed: invalid/unknown error code
This means your context went away while PyCUDA was still talking to
it. This will happen most often if you perform some invalid operation
(such as access out-of-bounds memory in a kernel). In this case, the
cuMemcpyDtoH operation could be at fault.
HTH,
Andreas
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