A standard for new page isolation steps like the following: 1, get_page(); #pin the page avoid be free 2, TestClearPageLRU(); #serialize other isolation, also memcg change 3, spin_lock on lru_lock; #serialize lru list access The step 2 could be optimzed/replaced in scenarios which page is unlikely be accessed by others. 在 2020/7/25 下午8:59, Alex Shi 写道: > The new version which bases on v5.8-rc6. It includes Hugh Dickins fix in > mm/swap.c and mm/mlock.c fix which Alexander Duyck pointed out, then > removes 'mm/mlock: reorder isolation sequence during munlock' > > Hi Johanness & Hugh & Alexander & Willy, > > Could you like to give a reviewed by since you address much of issue and > give lots of suggestions! Many thanks! > > Current lru_lock is one for each of node, pgdat->lru_lock, that guard for > lru lists, but now we had moved the lru lists into memcg for long time. Still > using per node lru_lock is clearly unscalable, pages on each of memcgs have > to compete each others for a whole lru_lock. This patchset try to use per > lruvec/memcg lru_lock to repleace per node lru lock to guard lru lists, make > it scalable for memcgs and get performance gain. > > Currently lru_lock still guards both lru list and page's lru bit, that's ok. > but if we want to use specific lruvec lock on the page, we need to pin down > the page's lruvec/memcg during locking. Just taking lruvec lock first may be > undermined by the page's memcg charge/migration. To fix this problem, we could > take out the page's lru bit clear and use it as pin down action to block the > memcg changes. That's the reason for new atomic func TestClearPageLRU. > So now isolating a page need both actions: TestClearPageLRU and hold the > lru_lock. > > The typical usage of this is isolate_migratepages_block() in compaction.c > we have to take lru bit before lru lock, that serialized the page isolation > in memcg page charge/migration which will change page's lruvec and new > lru_lock in it. > > The above solution suggested by Johannes Weiner, and based on his new memcg > charge path, then have this patchset. (Hugh Dickins tested and contributed much > code from compaction fix to general code polish, thanks a lot!). > > The patchset includes 3 parts: > 1, some code cleanup and minimum optimization as a preparation. > 2, use TestCleanPageLRU as page isolation's precondition > 3, replace per node lru_lock with per memcg per node lru_lock > > Following Daniel Jordan's suggestion, I have run 208 'dd' with on 104 > containers on a 2s * 26cores * HT box with a modefied case: > https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/tree/case-lru-file-readtwice > With this patchset, the readtwice performance increased about 80% > in concurrent containers. > > Thanks Hugh Dickins and Konstantin Khlebnikov, they both brought this > idea 8 years ago, and others who give comments as well: Daniel Jordan, > Mel Gorman, Shakeel Butt, Matthew Wilcox etc. > > Thanks for Testing support from Intel 0day and Rong Chen, Fengguang Wu, > and Yun Wang. Hugh Dickins also shared his kbuild-swap case. Thanks! > > > Alex Shi (19): > mm/vmscan: remove unnecessary lruvec adding > mm/page_idle: no unlikely double check for idle page counting > mm/compaction: correct the comments of compact_defer_shift > mm/compaction: rename compact_deferred as compact_should_defer > mm/thp: move lru_add_page_tail func to huge_memory.c > mm/thp: clean up lru_add_page_tail > mm/thp: remove code path which never got into > mm/thp: narrow lru locking > mm/memcg: add debug checking in lock_page_memcg > mm/swap: fold vm event PGROTATED into pagevec_move_tail_fn > mm/lru: move lru_lock holding in func lru_note_cost_page > mm/lru: move lock into lru_note_cost > mm/lru: introduce TestClearPageLRU > mm/compaction: do page isolation first in compaction > mm/thp: add tail pages into lru anyway in split_huge_page() > mm/swap: serialize memcg changes in pagevec_lru_move_fn > mm/lru: replace pgdat lru_lock with lruvec lock > mm/lru: introduce the relock_page_lruvec function > mm/pgdat: remove pgdat lru_lock > > Hugh Dickins (2): > mm/vmscan: use relock for move_pages_to_lru > mm/lru: revise the comments of lru_lock > > Documentation/admin-guide/cgroup-v1/memcg_test.rst | 15 +- > Documentation/admin-guide/cgroup-v1/memory.rst | 21 +-- > Documentation/trace/events-kmem.rst | 2 +- > Documentation/vm/unevictable-lru.rst | 22 +-- > include/linux/compaction.h | 4 +- > include/linux/memcontrol.h | 98 ++++++++++ > include/linux/mm_types.h | 2 +- > include/linux/mmzone.h | 6 +- > include/linux/page-flags.h | 1 + > include/linux/swap.h | 4 +- > include/trace/events/compaction.h | 2 +- > mm/compaction.c | 113 ++++++++---- > mm/filemap.c | 4 +- > mm/huge_memory.c | 48 +++-- > mm/memcontrol.c | 71 ++++++- > mm/memory.c | 3 - > mm/mlock.c | 43 +++-- > mm/mmzone.c | 1 + > mm/page_alloc.c | 1 - > mm/page_idle.c | 8 - > mm/rmap.c | 4 +- > mm/swap.c | 203 ++++++++------------- > mm/swap_state.c | 2 - > mm/vmscan.c | 174 ++++++++++-------- > mm/workingset.c | 2 - > 25 files changed, 510 insertions(+), 344 deletions(-) >
