On 17/04/2023 08:56, Yin Fengwei wrote: > Ryan tried to enable the large folio for anonymous mapping [1]. > > Unlike large folio for page cache which doesn't trigger frequent page > allocation/free, large folio for anonymous mapping is allocated/freeed > more frequently. So large folio for anonymous mapping exposes some lock > contention. > > Ryan mentioned the deferred queue lock in [1]. We also met other two > lock contention: lru lock and zone lock. > > This series tries to mitigate the deferred queue lock and reduce lru > lock in some level. > > The patch1 tries to reduce deferred queue lock by not acquiring queue > lock when check whether the folio is in deferred list or not. Test > page fault1 of will-it-scale showed 60% deferred queue lock contention > reduction. > > The patch2 tries to reduce lru lock by allowing batched add large folio > to lru list. Test page fault1 of will-it-scale showed 20% lru lock > contention reduction. > > The zone lock contention happens on large folio free path and related > with commit f26b3fa04611 "mm/page_alloc: limit number of high-order > pages on PCP during bulk free" and will not be address by this series. I applied this series on top of mine and did some quick perf tests. See https://lore.kernel.org/linux-mm/d9987135-3a8a-e22c-13f9-506d3249332b@xxxxxxx/. The change is certainly reducing time spent in the kernel, but there are other problems I'll need to investigate. So: Tested-by: Ryan Roberts <ryan.roberts@xxxxxxx> Thanks, Ryan > > > [1] > https://lore.kernel.org/linux-mm/20230414130303.2345383-1-ryan.roberts@xxxxxxx/ > > Yin Fengwei (2): > THP: avoid lock when check whether THP is in deferred list > lru: allow large batched add large folio to lru list > > include/linux/pagevec.h | 19 +++++++++++++++++-- > mm/huge_memory.c | 19 ++++++++++++++++--- > mm/swap.c | 3 +-- > 3 files changed, 34 insertions(+), 7 deletions(-) >
