diff options
| author | Andy Whitcroft <apw@shadowen.org> | 2007-05-06 14:49:14 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-07 12:12:52 -0700 |
| commit | 14e072984179d3d421bf9ab75cc67e0961742841 (patch) | |
| tree | 65a5a6f7d9756b8e7010278b58908d04da257a28 | |
| parent | ac267728f13c55017ed5ee243c9c3166e27ab929 (diff) | |
add pfn_valid_within helper for sub-MAX_ORDER hole detection
Generally we work under the assumption that memory the mem_map array is
contigious and valid out to MAX_ORDER_NR_PAGES block of pages, ie. that if we
have validated any page within this MAX_ORDER_NR_PAGES block we need not check
any other. This is not true when CONFIG_HOLES_IN_ZONE is set and we must
check each and every reference we make from a pfn.
Add a pfn_valid_within() helper which should be used when scanning pages
within a MAX_ORDER_NR_PAGES block when we have already checked the validility
of the block normally with pfn_valid(). This can then be optimised away when
we do not have holes within a MAX_ORDER_NR_PAGES block of pages.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/mmzone.h | 12 | ||||
| -rw-r--r-- | mm/page_alloc.c | 8 |
2 files changed, 14 insertions, 6 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index ee9e3143df4..2f1544e8304 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -784,6 +784,18 @@ void sparse_init(void); void memory_present(int nid, unsigned long start, unsigned long end); unsigned long __init node_memmap_size_bytes(int, unsigned long, unsigned long); +/* + * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we + * need to check pfn validility within that MAX_ORDER_NR_PAGES block. + * pfn_valid_within() should be used in this case; we optimise this away + * when we have no holes within a MAX_ORDER_NR_PAGES block. + */ +#ifdef CONFIG_HOLES_IN_ZONE +#define pfn_valid_within(pfn) pfn_valid(pfn) +#else +#define pfn_valid_within(pfn) (1) +#endif + #endif /* !__ASSEMBLY__ */ #endif /* __KERNEL__ */ #endif /* _LINUX_MMZONE_H */ diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 019ceda6a8b..f564717d22f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -156,10 +156,8 @@ static int page_outside_zone_boundaries(struct zone *zone, struct page *page) static int page_is_consistent(struct zone *zone, struct page *page) { -#ifdef CONFIG_HOLES_IN_ZONE - if (!pfn_valid(page_to_pfn(page))) + if (!pfn_valid_within(page_to_pfn(page))) return 0; -#endif if (zone != page_zone(page)) return 0; @@ -346,10 +344,8 @@ __find_combined_index(unsigned long page_idx, unsigned int order) static inline int page_is_buddy(struct page *page, struct page *buddy, int order) { -#ifdef CONFIG_HOLES_IN_ZONE - if (!pfn_valid(page_to_pfn(buddy))) + if (!pfn_valid_within(page_to_pfn(buddy))) return 0; -#endif if (page_zone_id(page) != page_zone_id(buddy)) return 0; |