On Thu, Jul 20, 2023 at 5:30 AM Ryan Roberts <ryan.roberts@xxxxxxx> wrote: > > Like page_remove_rmap() but batch-removes the rmap for a range of pages > belonging to a folio. This can provide a small speedup due to less > manipuation of the various counters. But more crucially, if removing the > rmap for all pages of a folio in a batch, there is no need to > (spuriously) add it to the deferred split list, which saves significant > cost when there is contention for the split queue lock. > > All contained pages are accounted using the order-0 folio (or base page) > scheme. > > page_remove_rmap() is refactored so that it forwards to > folio_remove_rmap_range() for !compound cases, and both functions now > share a common epilogue function. The intention here is to avoid > duplication of code. > > Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> > --- > include/linux/rmap.h | 2 + > mm/rmap.c | 125 ++++++++++++++++++++++++++++++++----------- > 2 files changed, 97 insertions(+), 30 deletions(-) > > diff --git a/include/linux/rmap.h b/include/linux/rmap.h > index b87d01660412..f578975c12c0 100644 > --- a/include/linux/rmap.h > +++ b/include/linux/rmap.h > @@ -200,6 +200,8 @@ void page_add_file_rmap(struct page *, struct vm_area_struct *, > bool compound); > void page_remove_rmap(struct page *, struct vm_area_struct *, > bool compound); > +void folio_remove_rmap_range(struct folio *folio, struct page *page, > + int nr, struct vm_area_struct *vma); I prefer folio_remove_rmap_range(page, nr, vma). Passing both the folio and the starting page seems redundant to me. Matthew, is there a convention (function names, parameters, etc.) for operations on a range of pages within a folio? And regarding the refactor, what I have in mind is that folio_remove_rmap_range() is the core API and page_remove_rmap() is just a wrapper around it, i.e., folio_remove_rmap_range(page, 1, vma). Let me post a diff later and see if it makes sense to you.
