Messages in this thread | | | Date | Thu, 22 Mar 2007 10:23:27 +1100 | From | Nick Piggin <> | Subject | Re: [PATCH 1/3] add pfn_valid_within helper for sub-MAX_ORDER hole detection |
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Andy Whitcroft wrote: > 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.
Nice cleanup. Horrible name ;) Calls read like "is the pfn valid within pfn".
I can't think of anything really good, but I think, say, pfn_valid_within_block or pfn_valid_within_valid_block would be a bit better. You still get a slight net savings in keystrokes!
Thanks, Nick
> > Signed-off-by: Andy Whitcroft <apw@shadowen.org> > Acked-by: Mel Gorman <mel@csn.ul.ie> > --- > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 7206c77..8c87d79 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -837,6 +837,18 @@ 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 3d7a9e2..695b5a6 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -206,10 +206,8 @@ 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; > > @@ -411,10 +409,8 @@ __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; > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >
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