Freeing CUDA memory painfully slow

Question

I am allocating some float arrays (pretty large, ie 9,000,000 elements) on the GPU using `cudaMalloc((void**)&(storage->data), size * sizeof(float))`. In the end of my program, I free this memory using `cudaFree(storage->data);`. The problem is that the first deallocation is really slow, around 10 seconds, whereas the others are nearly instantaneous. My question is the following : what could cause this difference ? Is deallocation memory on a GPU usually that slow ?

Accepted Answer

As pointed out on the NVIDIA forums, it's almost certainly a problem with the way you are timing things rather than with cudaFree.

Freeing CUDA memory painfully slow

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