On Mon, 12 Jun 2023 21:02:56 +0800 Yunsheng Lin wrote: > +2. page_pool_alloc_frag(): allocate memory with page splitting when driver knows > + that the memory it need is always smaller than or equal to half of the page > + allocated from page pool. Page splitting enables memory saving and thus avoid > + TLB/cache miss for data access, but there also is some cost to implement page > + splitting, mainly some cache line dirtying/bouncing for 'struct page' and > + atomic operation for page->pp_frag_count. > + > +3. page_pool_alloc(): allocate memory with or without page splitting depending > + on the requested memory size when driver doesn't know the size of memory it > + need beforehand. It is a mix of the above two case, so it is a wrapper of the > + above API to simplify driver's interface for memory allocation with least > + memory utilization and performance penalty. Seems like the semantics of page_pool_alloc() are always better than page_pool_alloc_frag(). Is there a reason to keep these two separate?
