On 10/8/21 15:17, Matthew Wilcox wrote: > On Thu, Oct 07, 2021 at 04:35:54PM -0700, Andrew Morton wrote: >> On Thu, 7 Oct 2021 21:55:21 +0100 Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote: >>> My first response is an appeal to authority -- release_pages() does >>> this same thing. Only it takes an array, constructs a list and passes >>> that to put_unref_page_list(). So if that's slower (and lists _are_ >>> slower than arrays), we should have a put_unref_page_array(). >> >> And put_unref_page_list() does two passes across the list! >> >> <quietly sobs> >> >> Here is my beautiful release_pages(), as disrtibuted in linux-2.5.33: > > I think that looks much better! > For what is worth, something that was suggested by Jason over the unpin_user_pages* improvements series was to apply the same trick to how we iterate a page array to release_pages(). Purpose would be to batch the page refcount update if you pass N contiguous struct pages. Joao
