cudaMallocArray returns null pointer?

Accelerated Computing CUDA CUDA Programming and Performance
1

Here’s the code I’m trying to run:

       // Create a 3 channel format description

        cudaChannelFormatDesc channelDesc= cudaCreateChannelDesc(32, 32, 32, 0, cudaChannelFormatKindFloat);

        

        // Allocate array

        cudaMallocArray(&posBuff, &channelDesc, m_imgWidth, m_imgHeight);

        

        // Now we upload host memory to GPU

        cudaMemcpyToArray(posBuff, 0, 0, tempBuff, m_imgWidth*m_imgHeight*3*sizeof(float), cudaMemcpyHostToDevice);

posBuff is a cudaArray*

The problem is cudaMallocArray isn’t setting posBuff to anything, it comes back out as a null pointer, so the cudaMemcpyToArray call seg faults. m_imgWidth and m_imgHeight are both 512, so there should be plenty of memory to hold the array.

2

The channel format is invalid. Like all previous NVIDIA GPUs, internal texture layout is either 1,2 or 4 channels.

Peter

3

Really? I wrote this code using the openGL API and have a 3 element texture. Does it just internalize it to four elements and then drop the last one?

4

Yep, you’ve been wasting GPU memory. See the internal texture format spec.

Peter