Creating Multiple VkFFTApplication plans about vkfft HOT 4 CLOSED

Hello,

creating app structure like this VkFFTApplication app = {}; makes it scope local - meaning it will be deallocated once vkfft_create call finishes. What you want is likely to call VkFFTApplication app = {}; outside the vkfft_create and then pass the pointer &app to vkfft_create. Or you can manually allocate memory for app in vkfft_create with VkFFTApplication* app = (VkFFTApplication*)calloc(1, sizeof(VkFFTApplication)); and free it later in vkfft_free call, for example.

Best regards,
Dmitrii

from vkfft.

Hello Dmitrii,

Thank you for your quick response.
Second option really made it work.

I changed subroutine signature a bit:

void vkfft_create(int size, int how_many, int double_precision, VkFFTApplication **app_handle) {
  VkFFTConfiguration config = {};
  VkFFTApplication* app = (VkFFTApplication*)calloc(1, sizeof(VkFFTApplication));
  // Populating config values
  // ...
  VKFFT_CALL(initializeVkFFT(app, config));
  *app_handle = app;
}

and I can clearly see that app is pointing to different locations.
Thank you.

I have another unrelated question.
Are there any memory estimations of memory that VkFFT will allocate internally for M batches of DCT2 transforms of size N?

from vkfft.

For DCT2 the additional memory usage depends on the system size. If system fits in shared memory of a GPU (<4096, approximately) it will not use additional memory (regardless of M). for bigger sequences it depends if system is decomposable as small primes or can be done with Rader algorithm - then the additional size will be 2x the system size (M*N). If the system uses Bluestein's algorithm, the size will be 4x. Some small additional memory is used for twiddle factors (at least M times smaller).

from vkfft.

Thanks for clarification.
I'm closing this issue.

from vkfft.