Understanding different modes of the Driver

[divyanshk]

Firstly, congrats on the repo!

I am trying better understand the framework. Can you explain a bit more about the different modes "executor", "scheduler", "ray". https://github.com/deepseek-ai/smallpond/blob/main/smallpond/execution/driver.py#L32

I have seen text on "ray" and "scheduler" mode in other places but not sure about the "executor" mode, especially since that is the default option used in the benchmarks.

cc. wangrunji0408
Thanks!