On Fri, Feb 1, 2013 at 6:40 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Fri, 18 Jan 2013 17:57:25 +0200 > "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > >> Hi, >> >> PAGE_CACHE_* macros were introduced long time ago in hope to implement >> page cache with larger chunks than one page in future. >> >> In fact it was never done. >> >> Some code paths assume PAGE_CACHE_SIZE <= PAGE_SIZE. E.g. we use >> zero_user_segments() to clear stale parts of page on cache filling, but >> the function is implemented only for individual small page. >> >> It's unlikely that global switch to PAGE_CACHE_SIZE > PAGE_SIZE will never >> happen since it will affect to much code at once. >> >> I think support of larger chunks in page cache can be in implemented in >> some form of THP with per-fs enabling. >> >> Is it time to get rid of PAGE_CACHE_* macros? >> I can prepare patchset if it's okay. > > The distinct PAGE_CACHE_SIZE has never been used for anything, but I do > kinda like it for documentary reasons: PAGE_SIZE is a raw, low-level > thing and PAGE_CACHE_SIZE is the specialized > we're-doing-pagecache-stuff thing. > > But I'm sure I could get used to not having it ;) Personally I always find such distinctions without a difference - like page_cache_release vs put_page - rather confusing, especially when working near the fs/mm boundary (for example in and under handle_pte_fault()) -- Michel "Walken" Lespinasse A program is never fully debugged until the last user dies. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>