[PATCH 3/3] mm: page_alloc: remove redundant set_freepage_migratetype() calls

From: Weijie Yang
Date: Tue Dec 09 2014 - 02:53:57 EST

The freepage_migratetype is a temporary cached value which represents
the free page's pageblock migratetype. Now we use it in two scenarios:

1. Use it as a cached value in page freeing path. This cached value
is temporary and non-100% update, which help us decide which pcp
freelist and buddy freelist the page should go rather than using
get_pfnblock_migratetype() to save some instructions.
When there is race between page isolation and free path, we need use
additional method to get a accurate value to put the free pages to
the correct freelist and get a precise free pages statistics.

2. Use it in page alloc path to update NR_FREE_CMA_PAGES statistics.

This patch aims at the scenario 1 and removes two redundant
set_freepage_migratetype() calls, which will make sense in the hot path.

Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
mm/page_alloc.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 616a2c9..99af01a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -775,7 +775,6 @@ static void __free_pages_ok(struct page *page, unsigned int order)
migratetype = get_pfnblock_migratetype(page, pfn);
__count_vm_events(PGFREE, 1 << order);
- set_freepage_migratetype(page, migratetype);
free_one_page(page_zone(page), page, pfn, order, migratetype);
@@ -1024,7 +1023,6 @@ int move_freepages(struct zone *zone,
order = page_order(page);
- set_freepage_migratetype(page, migratetype);
page += 1 << order;
pages_moved += 1 << order;

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