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From: Muchun Song <songmuchun@bytedance.com>
To: akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Muchun Song <songmuchun@bytedance.com>
Subject: [PATCH] mm/page_alloc: speeding up the iteration of max_order
Date: Wed,  2 Dec 2020 20:18:38 +0800	[thread overview]
Message-ID: <20201202121838.75218-1-songmuchun@bytedance.com> (raw)

When we free a page whose order is very close to MAX_ORDER and greater
than pageblock_order, it wastes some CPU cycles to increase max_order
to MAX_ORDER one by one and check the pageblock migratetype of that page
repeatedly especially when MAX_ORDER is much larger than pageblock_order.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/page_alloc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 141f12e5142c..959541234e1d 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -1041,7 +1041,7 @@ static inline void __free_one_page(struct page *page,
 		pfn = combined_pfn;
 		order++;
 	}
-	if (max_order < MAX_ORDER) {
+	if (max_order < MAX_ORDER && order < MAX_ORDER - 1) {
 		/* If we are here, it means order is >= pageblock_order.
 		 * We want to prevent merge between freepages on isolate
 		 * pageblock and normal pageblock. Without this, pageblock
@@ -1062,6 +1062,8 @@ static inline void __free_one_page(struct page *page,
 						is_migrate_isolate(buddy_mt)))
 				goto done_merging;
 		}
+		if (unlikely(order != max_order - 1))
+			max_order = order + 1;
 		max_order++;
 		goto continue_merging;
 	}
-- 
2.11.0


             reply	other threads:[~2020-12-02 12:21 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-02 12:18 Muchun Song [this message]
2020-12-03 17:37 ` Vlastimil Babka
2020-12-04  4:03   ` [External] " Muchun Song
2020-12-04 10:28     ` Vlastimil Babka
2020-12-04 11:11       ` Muchun Song

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