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author | KyongHo Cho <pullip.cho@samsung.com> | 2011-01-13 15:47:24 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-01-13 17:32:48 -0800 |
commit | 43506fad21ca3d8dc59e768ff458f7c5e5c01086 (patch) | |
tree | b594f240a780e3547341530fedabb6ac4735ff41 /mm | |
parent | 5520e89485252c759ee60d313e9422447659947b (diff) | |
download | linux-stable-43506fad21ca3d8dc59e768ff458f7c5e5c01086.tar.gz linux-stable-43506fad21ca3d8dc59e768ff458f7c5e5c01086.tar.bz2 linux-stable-43506fad21ca3d8dc59e768ff458f7c5e5c01086.zip |
mm/page_alloc.c: simplify calculation of combined index of adjacent buddy lists
The previous approach of calucation of combined index was
page_idx & ~(1 << order))
but we have same result with
page_idx & buddy_idx
This reduces instructions slightly as well as enhances readability.
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix used-unintialised warning]
Signed-off-by: KyongHo Cho <pullip.cho@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/page_alloc.c | 25 |
1 files changed, 10 insertions, 15 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 9dfe49bceff4..bda1db301d44 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -427,18 +427,10 @@ static inline void rmv_page_order(struct page *page) * * Assumption: *_mem_map is contiguous at least up to MAX_ORDER */ -static inline struct page * -__page_find_buddy(struct page *page, unsigned long page_idx, unsigned int order) -{ - unsigned long buddy_idx = page_idx ^ (1 << order); - - return page + (buddy_idx - page_idx); -} - static inline unsigned long -__find_combined_index(unsigned long page_idx, unsigned int order) +__find_buddy_index(unsigned long page_idx, unsigned int order) { - return (page_idx & ~(1 << order)); + return page_idx ^ (1 << order); } /* @@ -500,6 +492,7 @@ static inline void __free_one_page(struct page *page, { unsigned long page_idx; unsigned long combined_idx; + unsigned long uninitialized_var(buddy_idx); struct page *buddy; if (unlikely(PageCompound(page))) @@ -514,7 +507,8 @@ static inline void __free_one_page(struct page *page, VM_BUG_ON(bad_range(zone, page)); while (order < MAX_ORDER-1) { - buddy = __page_find_buddy(page, page_idx, order); + buddy_idx = __find_buddy_index(page_idx, order); + buddy = page + (buddy_idx - page_idx); if (!page_is_buddy(page, buddy, order)) break; @@ -522,7 +516,7 @@ static inline void __free_one_page(struct page *page, list_del(&buddy->lru); zone->free_area[order].nr_free--; rmv_page_order(buddy); - combined_idx = __find_combined_index(page_idx, order); + combined_idx = buddy_idx & page_idx; page = page + (combined_idx - page_idx); page_idx = combined_idx; order++; @@ -539,9 +533,10 @@ static inline void __free_one_page(struct page *page, */ if ((order < MAX_ORDER-2) && pfn_valid_within(page_to_pfn(buddy))) { struct page *higher_page, *higher_buddy; - combined_idx = __find_combined_index(page_idx, order); - higher_page = page + combined_idx - page_idx; - higher_buddy = __page_find_buddy(higher_page, combined_idx, order + 1); + combined_idx = buddy_idx & page_idx; + higher_page = page + (combined_idx - page_idx); + buddy_idx = __find_buddy_index(combined_idx, order + 1); + higher_buddy = page + (buddy_idx - combined_idx); if (page_is_buddy(higher_page, higher_buddy, order + 1)) { list_add_tail(&page->lru, &zone->free_area[order].free_list[migratetype]); |