tex2D exits kernel

Accelerated Computing CUDA CUDA Programming and Performance
1

Hi everyone,

I have gotten my hands on a kernel which worked just fine (or seemed to anyway) on cuda 2.0. However, upon switching to cuda 2.1 calls to tex2D constantly fail - basically the kernel would simply exit (aka: break out/return) at that very function call, without any error flag set.
Unfortunately the kernel is fairly large and I am currently looking for input as to how to debug this.
Has anyone ever heard of something like this happening?

This happens both in emulation & device mode on at least a GeForce 8800 GTX and a Quadro FX 5600. If in device mode, it seems to happen less often - though still quite a few times. Furthermore it happens more often on the Quadro FX 5600 than the GeForce 8800 GTX.

Would love to get any advice on this.

Kind regards,
MHOOO

2

Are you positive there is no error flag set? Have you explicitly put:

cudaThreadSynchronize();

error = cudaGetLastError()

if (error != cudaSuccess)

   print error

after your kernel?

One case where I can think of this occuring would be if your texture is not bound. Or if you bound it with with the wrong bind comand (the one for tex1Dfetch).

3

Yes, I always check with:

int errorCode = cudaThreadSynchronize();

	if (errorCode != cudaSuccess)

		printf("cuda error: %d\n", errorCode);

Now I’m not sure what tex1Dfetch uses as a bind command, however I use the following for tex2D:

texture<float4, 2, cudaReadModeElementType> myTex;

cudaChannelFormatDesc channelDescFloat4 = cudaCreateChannelDesc(32, 32, 32, 32, cudaChannelFormatKindFloat);

rc = cudaBindTextureToArray(myTex, myCudaArray, channelDescFloat4); assert(rc == cudaSuccess);

[...tex2D here...]

cudaUnbindTexture(myTex);

I’m used to get real kernel errors (and not silent failures) when accessing a texture which is unbound though - so I figured thats not it.

I also made sure the texture is defined & bound inside the same compiled unit as its being used from.

Kind regards,

MHOOO

4

Looks like you have all the bases covered. I don’t have any further ideas.