On (19/04/07 09:35), Christoph Lameter didst pronounce:
> Variable Order Page Cache: Add basic allocation functions
>
> Extend __page_cache_alloc to take an order parameter and
> modify caller sites. Modify mapping_set_gfp_mask to set
> __GFP_COMP if the mapping requires higher order allocations.
>
> put_page() is already capable of handling compound pages. So
> there are no changes needed to release higher order page
> cache pages.
>
> Signed-off-by: Christoph Lameter <[email protected]>
>
> ---
> include/linux/pagemap.h | 15 +++++++++------
> mm/filemap.c | 9 +++++----
> 2 files changed, 14 insertions(+), 10 deletions(-)
>
> Index: linux-2.6.21-rc7/include/linux/pagemap.h
> ===================================================================
> --- linux-2.6.21-rc7.orig/include/linux/pagemap.h 2007-04-18 21:21:56.000000000 -0700
> +++ linux-2.6.21-rc7/include/linux/pagemap.h 2007-04-18 21:29:02.000000000 -0700
> @@ -32,6 +32,8 @@ static inline void mapping_set_gfp_mask(
> {
> m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) |
> (__force unsigned long)mask;
> + if (m->order)
> + m->flags |= __GFP_COMP;
This might need a comment. It might not be superclear that compound
pages have destructors that know how to lookup the order on free.
> }
>
> /*
> @@ -40,7 +42,7 @@ static inline void mapping_set_gfp_mask(
> * throughput (it can then be mapped into user
> * space in smaller chunks for same flexibility).
> *
> - * Or rather, it _will_ be done in larger chunks.
> + * This is the base page size
> */
> #define PAGE_CACHE_SHIFT PAGE_SHIFT
> #define PAGE_CACHE_SIZE PAGE_SIZE
> @@ -52,22 +54,23 @@ static inline void mapping_set_gfp_mask(
> void release_pages(struct page **pages, int nr, int cold);
>
> #ifdef CONFIG_NUMA
> -extern struct page *__page_cache_alloc(gfp_t gfp);
> +extern struct page *__page_cache_alloc(gfp_t gfp, int order);
> #else
> -static inline struct page *__page_cache_alloc(gfp_t gfp)
> +static inline struct page *__page_cache_alloc(gfp_t gfp, int order)
> {
> - return alloc_pages(gfp, 0);
> + return alloc_pages(gfp, order);
> }
> #endif
>
> static inline struct page *page_cache_alloc(struct address_space *x)
> {
> - return __page_cache_alloc(mapping_gfp_mask(x));
> + return __page_cache_alloc(mapping_gfp_mask(x), x->order);
> }
>
> static inline struct page *page_cache_alloc_cold(struct address_space *x)
> {
> - return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD);
> + return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD,
> + x->order);
> }
>
> typedef int filler_t(void *, struct page *);
> Index: linux-2.6.21-rc7/mm/filemap.c
> ===================================================================
> --- linux-2.6.21-rc7.orig/mm/filemap.c 2007-04-18 21:21:56.000000000 -0700
> +++ linux-2.6.21-rc7/mm/filemap.c 2007-04-18 21:28:30.000000000 -0700
> @@ -467,13 +467,13 @@ int add_to_page_cache_lru(struct page *p
> }
>
> #ifdef CONFIG_NUMA
> -struct page *__page_cache_alloc(gfp_t gfp)
> +struct page *__page_cache_alloc(gfp_t gfp, int order)
> {
> if (cpuset_do_page_mem_spread()) {
> int n = cpuset_mem_spread_node();
> - return alloc_pages_node(n, gfp, 0);
> + return alloc_pages_node(n, gfp, order);
> }
> - return alloc_pages(gfp, 0);
> + return alloc_pages(gfp, order);
> }
> EXPORT_SYMBOL(__page_cache_alloc);
> #endif
> @@ -803,7 +803,8 @@ grab_cache_page_nowait(struct address_sp
> page_cache_release(page);
> return NULL;
> }
> - page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS);
> + page = __page_cache_alloc(mapping_gfp_mask(mapping) & ~__GFP_FS,
> + mapping->order);
> if (page && add_to_page_cache_lru(page, mapping, index, GFP_KERNEL)) {
> page_cache_release(page);
> page = NULL;
> -
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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