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mm: create a separate slab for page->ptl allocation

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If DEBUG_SPINLOCK and DEBUG_LOCK_ALLOC are enabled spinlock_t on x86_64
is 72 bytes.  For page->ptl they will be allocated from kmalloc-96 slab,
so we loose 24 on each.  An average system can easily allocate few tens
thousands of page->ptl and overhead is significant.

Let's create a separate slab for page->ptl allocation to solve this.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2013-11-14 14:31:53 -08:00 committed by Linus Torvalds
parent 539edb5846
commit ea1e7ed337
3 changed files with 17 additions and 1 deletions
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9
include/linux/mm.h
View File

@ -1318,6 +1318,7 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a
#if USE_SPLIT_PTE_PTLOCKS #if USE_SPLIT_PTE_PTLOCKS
#if BLOATED_SPINLOCKS #if BLOATED_SPINLOCKS
void __init ptlock_cache_init(void);
extern bool ptlock_alloc(struct page *page); extern bool ptlock_alloc(struct page *page);
extern void ptlock_free(struct page *page); extern void ptlock_free(struct page *page);
@ -1326,6 +1327,7 @@ static inline spinlock_t *ptlock_ptr(struct page *page)
return page->ptl; return page->ptl;
} }
#else /* BLOATED_SPINLOCKS */ #else /* BLOATED_SPINLOCKS */
static inline void ptlock_cache_init(void) {}
static inline bool ptlock_alloc(struct page *page) static inline bool ptlock_alloc(struct page *page)
{ {
return true; return true;
@ -1378,10 +1380,17 @@ static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)
{ {
return &mm->page_table_lock; return &mm->page_table_lock;
} }
static inline void ptlock_cache_init(void) {}
static inline bool ptlock_init(struct page *page) { return true; } static inline bool ptlock_init(struct page *page) { return true; }
static inline void pte_lock_deinit(struct page *page) {} static inline void pte_lock_deinit(struct page *page) {}
#endif /* USE_SPLIT_PTE_PTLOCKS */ #endif /* USE_SPLIT_PTE_PTLOCKS */
static inline void pgtable_init(void)
{
ptlock_cache_init();
pgtable_cache_init();
}
static inline bool pgtable_page_ctor(struct page *page) static inline bool pgtable_page_ctor(struct page *page)
{ {
inc_zone_page_state(page, NR_PAGETABLE); inc_zone_page_state(page, NR_PAGETABLE);

2
init/main.c
View File

@ -473,7 +473,7 @@ static void __init mm_init(void)
mem_init(); mem_init();
kmem_cache_init(); kmem_cache_init();
percpu_init_late(); percpu_init_late();
pgtable_cache_init(); pgtable_init();
vmalloc_init(); vmalloc_init();
} }

7
mm/memory.c
View File

@ -4272,6 +4272,13 @@ void copy_user_huge_page(struct page *dst, struct page *src,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
#if USE_SPLIT_PTE_PTLOCKS && BLOATED_SPINLOCKS #if USE_SPLIT_PTE_PTLOCKS && BLOATED_SPINLOCKS
static struct kmem_cache *page_ptl_cachep;
void __init ptlock_cache_init(void)
{
page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
SLAB_PANIC, NULL);
}
bool ptlock_alloc(struct page *page) bool ptlock_alloc(struct page *page)
{ {
spinlock_t *ptl; spinlock_t *ptl;