From 4917e5d0499b5ae7b26b56fccaefddf9aec9369c Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Tue, 6 Jan 2009 14:39:17 -0800 Subject: [PATCH] mm: more likely reclaim MADV_SEQUENTIAL mappings File pages mapped only in sequentially read mappings are perfect reclaim canditates. This patch makes these mappings behave like weak references, their pages will be reclaimed unless they have a strong reference from a normal mapping as well. It changes the reclaim and the unmap path where they check if the page has been referenced. In both cases, accesses through sequentially read mappings will be ignored. Benchmark results from KOSAKI Motohiro: http://marc.info/?l=linux-mm&m=122485301925098&w=2 Signed-off-by: Johannes Weiner Signed-off-by: Rik van Riel Acked-by: KOSAKI Motohiro Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory.c | 3 ++- mm/rmap.c | 13 +++++++++++-- 2 files changed, 13 insertions(+), 3 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 5e0e91c..99e8d5c 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -767,7 +767,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, else { if (pte_dirty(ptent)) set_page_dirty(page); - if (pte_young(ptent)) + if (pte_young(ptent) && + likely(!VM_SequentialReadHint(vma))) mark_page_accessed(page); file_rss--; } diff --git a/mm/rmap.c b/mm/rmap.c index 53c56da..f01e922 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -360,8 +360,17 @@ static int page_referenced_one(struct page *page, goto out_unmap; } - if (ptep_clear_flush_young_notify(vma, address, pte)) - referenced++; + if (ptep_clear_flush_young_notify(vma, address, pte)) { + /* + * Don't treat a reference through a sequentially read + * mapping as such. If the page has been used in + * another mapping, we will catch it; if this other + * mapping is already gone, the unmap path will have + * set PG_referenced or activated the page. + */ + if (likely(!VM_SequentialReadHint(vma))) + referenced++; + } /* Pretend the page is referenced if the task has the swap token and is in the middle of a page fault. */ -- 2.7.4