The section is just a faq, if you click on the function names it leads you to the doc pages, which are very clear and what the functions do. There is no need to guess.
These numbers naturally don’t match exactly as nvidia-smi because of cuda context.
As said in the page, empty_cache only frees unused cached memory. If a memory block in the caching allocator backs any tensor, it won’t get freed. So memory_cached is not 0 after you call empty_cache.
I agree that resetting methods will be useful. Please submit a feature request.