[souprock]

My son hit that PCIe limit going the other direction, trying to get FFTW data on to the screen. The project:

https://github.com/kevinacahalan/piano_waterfall

With his motherboard it was impossible to keep both FFT views scrolling at full speed if they were large. He ended up creating a circular buffer in video memory so that he would be able to reduce the PCIe traffic to just the fresh new edge of the data. The fix doesn't work everywhere. Virtualization seems to break it, including with a Chromebook.

Is VkFFT a reasonable tool for attacking this problem? How difficult might it be to get the FFT result into the needed color component, gamma corrected and scaled, with all the other components?

[DTolm]

In VkFFT FFT is done as a part of the so called compute queue. There is no need to transfer data through PCI to show it on screen - there is a graphics queue that has this as its main purpose. You can use compute queue results in it and do all necessary calculations directly on the GPU. This type of task can benifit greatly from doing FFT on GPU. VkFFT can be append FFT to the user command buffer (list of commands), which can be then followed by additional user commands, like scaling, correcting, etc.

AFAIK, virtualization software right now has no or very limited access to the GPU, so no extensive graphics can be done through it.