From 349aef0bc4c7f07d685c977e12d0e2d0b5d0e6db Mon Sep 17 00:00:00 2001 From: Andrew Morton Date: Sun, 8 Jan 2006 01:04:36 -0800 Subject: [PATCH] [PATCH] shrink struct page Reduce the size of the pageframe for NR_CPUS>4, CONFIG_PREEMPT back to the minimal size by unionising both ->private and ->mapping with the pagetable lock. It uses an anonymous struct and hence requires gcc-3.x. Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 41 ++++++++++++++++++++++------------------- 1 file changed, 22 insertions(+), 19 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 7ff54242c5..df80e63903 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -223,24 +223,27 @@ struct page { * & limit reverse map searches. */ union { - unsigned long private; /* Mapping-private opaque data: - * usually used for buffer_heads - * if PagePrivate set; used for - * swp_entry_t if PageSwapCache - * When page is free, this indicates - * order in the buddy system. - */ + struct { + unsigned long private; /* Mapping-private opaque data: + * usually used for buffer_heads + * if PagePrivate set; used for + * swp_entry_t if PageSwapCache. + * When page is free, this + * indicates order in the buddy + * system. + */ + struct address_space *mapping; /* If low bit clear, points to + * inode address_space, or NULL. + * If page mapped as anonymous + * memory, low bit is set, and + * it points to anon_vma object: + * see PAGE_MAPPING_ANON below. + */ + }; #if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS - spinlock_t ptl; + spinlock_t ptl; #endif - } u; - struct address_space *mapping; /* If low bit clear, points to - * inode address_space, or NULL. - * If page mapped as anonymous - * memory, low bit is set, and - * it points to anon_vma object: - * see PAGE_MAPPING_ANON below. - */ + }; pgoff_t index; /* Our offset within mapping. */ struct list_head lru; /* Pageout list, eg. active_list * protected by zone->lru_lock ! @@ -261,8 +264,8 @@ struct page { #endif /* WANT_PAGE_VIRTUAL */ }; -#define page_private(page) ((page)->u.private) -#define set_page_private(page, v) ((page)->u.private = (v)) +#define page_private(page) ((page)->private) +#define set_page_private(page, v) ((page)->private = (v)) /* * FIXME: take this include out, include page-flags.h in @@ -815,7 +818,7 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a * overflow into the next struct page (as it might with DEBUG_SPINLOCK). * When freeing, reset page->mapping so free_pages_check won't complain. */ -#define __pte_lockptr(page) &((page)->u.ptl) +#define __pte_lockptr(page) &((page)->ptl) #define pte_lock_init(_page) do { \ spin_lock_init(__pte_lockptr(_page)); \ } while (0) -- 2.39.5