[QST] single/multi-cta support for topk larger than 1024

[zyx1986]

What is your question?

We benchmark the performance of cuvs for large topk(k > 1024). We find that the speed is much slower compared to the cases for k < 1024. We find that the search algorithm used for k > 1024 is MULTI_KERNEL instead of single/multi-cta.

We have three questions.

1. Will you please explain why single/multi-cta algorithms cannnot support large k?
2. How can we improve the performance for k > 1024?
3. Do you have a plan to support k > 1024 for single/multi-cta algorithms in the near future?