On 01/24/23 18:13, Matthew Wilcox wrote: > Once we get to the part of the folio journey where we have > one-pointer-per-page, we can't afford to maintain per-page state. > Currently we maintain a per-page mapcount, and that will have to go. > We can maintain extra state for a multi-page folio, but it has to be a > constant amount of extra state no matter how many pages are in the folio. > > My proposal is that we maintain a single mapcount per folio, and its > definition is the number of (vma, page table) tuples which have a > reference to any pages in this folio. Hi Matthew, finally took a look at this. Can you clarify your definition of 'page table' here? I think you are talking about all the entries within one page table page? Is that correct? It certainly makes sense in this context. I have always thought of page table as the entire tree structure starting at *pgd in the mm_struct. So, I was a bit confused. But, I now see elsewhere that 'page table' may refer to either. -- Mike Kravetz
