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 /include/linux/mmzone.h | |
| parent | mm/slab.c: proper prototypes (diff) | |
| download | linux-dev-14e072984179d3d421bf9ab75cc67e0961742841.tar.xz linux-dev-14e072984179d3d421bf9ab75cc67e0961742841.zip | |
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>
Diffstat (limited to 'include/linux/mmzone.h')
| -rw-r--r-- | include/linux/mmzone.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index ee9e3143df4f..2f1544e83042 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 */ |