From 1883e8ac96ddd73a87db7f2f8c06111148a3db6f Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Mon, 22 Jan 2024 21:01:53 +0800 Subject: mm: compaction: limit the suitable target page order to be less than cc->order It can not improve the fragmentation if we isolate the target free pages exceeding cc->order, especially when the cc->order is less than pageblock_order. For example, suppose the pageblock_order is MAX_ORDER (size is 4M) and cc->order is 2M THP size, we should not isolate other 2M free pages to be the migration target, which can not improve the fragmentation. Moreover this is also applicable for large folio compaction. Link: https://lkml.kernel.org/r/afcd9377351c259df7a25a388a4a0d5862b986f4.1705928395.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang Acked-by: Mel Gorman Cc: Vlastimil Babka Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/compaction.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm/compaction.c') diff --git a/mm/compaction.c b/mm/compaction.c index 12709d0bcf40..f146478b01bc 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1365,12 +1365,14 @@ static bool suitable_migration_target(struct compact_control *cc, { /* If the page is a large free page, then disallow migration */ if (PageBuddy(page)) { + int order = cc->order > 0 ? cc->order : pageblock_order; + /* * We are checking page_order without zone->lock taken. But * the only small danger is that we skip a potentially suitable * pageblock, so it's not worth to check order for valid range. */ - if (buddy_order_unsafe(page) >= pageblock_order) + if (buddy_order_unsafe(page) >= order) return false; } -- cgit