Ax serice API for GPU

[mgarrard]

Discussed in #2405

^{Originally posted by Wang-Zujian April 28, 2024}
When I set up my optimization with the service API, the CPU is always working, and my GPU is not working, is it because the functions I define that need to be optimized are all variables defined by numpy？ And how should I call the GPU to speed up my optimization?