OpenCL Theano - How to forcefully disable CUDA?

Question

After a series of pains, I have installed Theano on a machine with AMD graphics card - Radeon HD 5450 (Cedar).

Now, consider a following code.

import numpy
import theano
import theano.tensor as T
rng = numpy.random

N = 400         #number of samples
feats = 784     #dimensionality of features
D = (rng.randn(N, feats), rng.randint(size=N, low=0, high=2))
training_steps = 10000

# theano symbolic variables
x = T.matrix("x")
y = T.vector("y")
w = theano.shared(rng.randn(784), name="w")
b = theano.shared(0., name="b")

print("Initial Model:")
print(str(w.get_value()) + " " + str(b.get_value()) )

p_1 = 1/(1 + T.exp(-T.dot(x, w) - b))       # probability of target being 1
prediction = p_1 > 0.5                      # prediction threshold
xent = -y * T.log(p_1) - (1-y)*T.log(1-p_1) # cross-entropy loss function
cost = xent.mean() + 0.01 * (w**2).sum()    # cost - to be minimized
gw, gb = T.grad(cost, [w, b])

#compile it
train = theano.function(
                        inputs = [x, y],
                        outputs = [prediction, xent],
                        updates = {w: w - 0.1*gw, b: b - 0.1*gb}    )

predict = theano.function(inputs = [x], outputs = prediction)

#train it
for i in range (training_steps):
    pred, err = train(D[0], D[1])

print("Final Model: ")
print(str(w.get_value()) + " " + str(b.get_value()) )
print("Target values for D: " + str(D[1]))
print("Predictions on D: " + str(D[0]))

I think this code should work just fine. But I get a series of errors:

ERROR (theano.gof.opt): Optimization failure due to: local_gpua_hgemm
ERROR (theano.gof.opt): node: dot(x.T, Elemwise{sub,no_inplace}.0)
ERROR (theano.gof.opt): TRACEBACK:
ERROR (theano.gof.opt): Traceback (most recent call last):
  File "/home/user/anaconda3/lib/python3.5/site-packages/theano/gof/opt.py", line 1772, in process_node
    replacements = lopt.transform(node)
  File "/home/user/anaconda3/lib/python3.5/site-packages/theano/sandbox/gpuarray/opt.py", line 140, in local_opt
    new_op = maker(node, context_name)
  File "/home/user/anaconda3/lib/python3.5/site-packages/theano/sandbox/gpuarray/opt.py", line 732, in local_gpua_hgemm
    if nvcc_compiler.nvcc_version < '7.5':
TypeError: unorderable types: NoneType() < str()

And I get the same set of messages multiple times. Then at the end:

  File "/home/user/anaconda3/lib/python3.5/site-packages/pygpu-0.2.1-py3.5-linux-x86_64.egg/pygpu/elemwise.py", line 286, in __init__
    **self.flags)
  File "pygpu/gpuarray.pyx", line 1950, in pygpu.gpuarray.GpuKernel.__cinit__ (pygpu/gpuarray.c:24214)
  File "pygpu/gpuarray.pyx", line 467, in pygpu.gpuarray.kernel_init (pygpu/gpuarray.c:7174)
pygpu.gpuarray.UnsupportedException: ('The following error happened while compiling the node', GpuElemwise{Composite{((-i0) - i1)}}[(0, 0)]<gpuarray>(GpuFromHost<None>.0, InplaceGpuDimShuffle{x}.0), '\n', b'Device does not support operation')

Does this mean I cannot use this GPU or I have done something wrong in my code. Moreover, from the errors, it seems there is been a search for nvcc. But I do not have CUDA, I have opencl.

>>> import theano
Mapped name None to device opencl0:0: Cedar

also:

>>> from theano import config
>>> config.device
'opencl0:0'
>>> config.cuda
<theano.configparser.AddConfigVar.<locals>.SubObj object at 0x7fba9dee7d30>
>>> config.nvcc
<theano.configparser.AddConfigVar.<locals>.SubObj object at 0x7fba9e5967f0>
>>> config.gpu
<theano.configparser.AddConfigVar.<locals>.SubObj object at 0x7fbaa9f61828>

So how do I go from here? Is there way to make sure clcc is searched instead of nvcc.

PS_1: hello world works. PS_2: System = 14.04 64 bit

Answer 1

OpenCL is not yet supported by Theano. As a result, only NVIDIA GPUs are supported.

The status of OpenCL is recorded on GitHub.

You need to disable GPU operation by setting device=cpu in your Theano config. There are multiple ways to do this (i.e. via THEANO_FLAGS environment variable or via a .theanorc file; see documentation).

Before running the script, try setting

export THEANO_FLAGS=device=cpu,floatX=float64

Your situation may need additional configuration options. See the documentation for more.