I have a nit on part 01/33, but will respond directly there. For the series: Reviewed-by: William Kucharski <william.kucharski@xxxxxxxxxx> > On May 11, 2021, at 3:47 PM, Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> wrote: > > Managing memory in 4KiB pages is a serious overhead. Many benchmarks > benefit from a larger "page size". As an example, an earlier iteration > of this idea which used compound pages (and wasn't particularly tuned) > got a 7% performance boost when compiling the kernel. > > Using compound pages or THPs exposes a weakness of our type system. > Functions are often unprepared for compound pages to be passed to them, > and may only act on PAGE_SIZE chunks. Even functions which are aware of > compound pages may expect a head page, and do the wrong thing if passed > a tail page. > > We also waste a lot of instructions ensuring that we're not looking at > a tail page. Almost every call to PageFoo() contains one or more hidden > calls to compound_head(). This also happens for get_page(), put_page() > and many more functions. There does not appear to be a way to tell gcc > that it can cache the result of compound_head(), nor is there a way to > tell it that compound_head() is idempotent. > > This patch series uses a new type, the struct folio, to manage memory. > It provides some basic infrastructure that's worthwhile in its own right, > shrinking the kernel by about 5kB of text. > > Since v9: > - Rebase onto mmotm 2021-05-10-21-46 > - Add folio_memcg() definition for !MEMCG (intel lkp) > - Change folio->private from an unsigned long to a void * > - Use folio_page() to implement folio_file_page() > - Add folio_try_get() and folio_try_get_rcu() > - Trim back down to just the first few patches, which are better-reviewed. > v9: https://lore.kernel.org/linux-mm/20210505150628.111735-1-willy@xxxxxxxxxxxxx/ > v8: https://lore.kernel.org/linux-mm/20210430180740.2707166-1-willy@xxxxxxxxxxxxx/ > > Matthew Wilcox (Oracle) (33): > mm: Introduce struct folio > mm: Add folio_pgdat and folio_zone > mm/vmstat: Add functions to account folio statistics > mm/debug: Add VM_BUG_ON_FOLIO and VM_WARN_ON_ONCE_FOLIO > mm: Add folio reference count functions > mm: Add folio_put > mm: Add folio_get > mm: Add folio_try_get_rcu > mm: Add folio flag manipulation functions > mm: Add folio_young and folio_idle > mm: Handle per-folio private data > mm/filemap: Add folio_index, folio_file_page and folio_contains > mm/filemap: Add folio_next_index > mm/filemap: Add folio_offset and folio_file_offset > mm/util: Add folio_mapping and folio_file_mapping > mm: Add folio_mapcount > mm/memcg: Add folio wrappers for various functions > mm/filemap: Add folio_unlock > mm/filemap: Add folio_lock > mm/filemap: Add folio_lock_killable > mm/filemap: Add __folio_lock_async > mm/filemap: Add __folio_lock_or_retry > mm/filemap: Add folio_wait_locked > mm/swap: Add folio_rotate_reclaimable > mm/filemap: Add folio_end_writeback > mm/writeback: Add folio_wait_writeback > mm/writeback: Add folio_wait_stable > mm/filemap: Add folio_wait_bit > mm/filemap: Add folio_wake_bit > mm/filemap: Convert page wait queues to be folios > mm/filemap: Add folio private_2 functions > fs/netfs: Add folio fscache functions > mm: Add folio_mapped > > Documentation/core-api/mm-api.rst | 4 + > Documentation/filesystems/netfs_library.rst | 2 + > fs/afs/write.c | 9 +- > fs/cachefiles/rdwr.c | 16 +- > fs/io_uring.c | 2 +- > include/linux/memcontrol.h | 63 ++++ > include/linux/mm.h | 174 ++++++++-- > include/linux/mm_types.h | 71 ++++ > include/linux/mmdebug.h | 20 ++ > include/linux/netfs.h | 77 +++-- > include/linux/page-flags.h | 230 ++++++++++--- > include/linux/page_idle.h | 99 +++--- > include/linux/page_ref.h | 158 ++++++++- > include/linux/pagemap.h | 358 ++++++++++++-------- > include/linux/swap.h | 7 +- > include/linux/vmstat.h | 107 ++++++ > mm/Makefile | 2 +- > mm/filemap.c | 315 ++++++++--------- > mm/folio-compat.c | 43 +++ > mm/internal.h | 1 + > mm/memory.c | 8 +- > mm/page-writeback.c | 72 ++-- > mm/page_io.c | 4 +- > mm/swap.c | 18 +- > mm/swapfile.c | 8 +- > mm/util.c | 59 ++-- > 26 files changed, 1374 insertions(+), 553 deletions(-) > create mode 100644 mm/folio-compat.c > > -- > 2.30.2 > >
