From 231f8c7127e37edcd4d9e3f87e0f9fcf0e90d902 Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Fri, 12 Apr 2024 11:27:04 +0800 Subject: [PATCH] mm: page_alloc: allowing mTHP compaction to capture the freed page directly Currently, compaction_capture() does not allow lower-order allocations to directly capture the movable free pages, even though lower-order allocations might also be requesting movable pages, that can lead to more compaction scanning. And, with the enablement of mTHP, such situations will become more common. Thus allowing lower-order (mTHP) allocations of movable page types directly capture the movable free pages can avoid unnecessary compaction scanning, meanwhile that won't pollute the movable pageblock. With testing 1M mTHP compaction, it can be seen that compaction scanning is significantly reduced. mm-unstable patched Ops Compaction pages isolated 116598741.00 120946702.00 Ops Compaction migrate scanned 1764870054.00 1488621550.00 Ops Compaction free scanned 7707879039.00 4986299318.00 Ops Compact scan efficiency 22.90 29.85 Ops Compaction cost 73797.69 72933.48 Link: https://lkml.kernel.org/r/8118a5d66a034736a48433beddaca60ed78577c4.1712892329.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang Reviewed-by: Zi Yan Acked-by: Johannes Weiner Cc: David Hildenbrand Cc: "Huang, Ying" Cc: Mel Gorman Cc: Ryan Roberts Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/page_alloc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 45fccbcda763..2e22ce5675ca 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -595,12 +595,14 @@ compaction_capture(struct capture_control *capc, struct page *page, return false; /* - * Do not let lower order allocations pollute a movable pageblock. + * Do not let lower order allocations pollute a movable pageblock + * unless compaction is also requesting movable pages. * This might let an unmovable request use a reclaimable pageblock * and vice-versa but no more than normal fallback logic which can * have trouble finding a high-order free page. */ - if (order < pageblock_order && migratetype == MIGRATE_MOVABLE) + if (order < pageblock_order && migratetype == MIGRATE_MOVABLE && + capc->cc->migratetype != MIGRATE_MOVABLE) return false; capc->page = page;