diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2014-01-21 15:49:07 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-01-21 16:19:44 -0800 |
| commit | b35f1819acd9243a3ff7ad25b1fa8bd6bfe80fb2 (patch) | |
| tree | 140f810d09226caa12531e0a02126af64e71e314 | |
| parent | 943dca1a1fcbccb58de944669b833fd38a6c809b (diff) | |
mm: create a separate slab for page->ptl allocation
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.
To make sure that it really works this time, some numbers from my test
machine (just booted, no load):
Before:
# grep '^\(kmalloc-96\|page->ptl\)' /proc/slabinfo
kmalloc-96 31987 32190 128 30 1 : tunables 120 60 8 : slabdata 1073 1073 92
After:
# grep '^\(kmalloc-96\|page->ptl\)' /proc/slabinfo
page->ptl 27516 28143 72 53 1 : tunables 120 60 8 : slabdata 531 531 9
kmalloc-96 3853 5280 128 30 1 : tunables 120 60 8 : slabdata 176 176 0
Note that the patch is useful not only for debug case, but also for
PREEMPT_RT, where spinlock_t is always bloated.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/mm.h | 12 | ||||
| -rw-r--r-- | init/main.c | 2 | ||||
| -rw-r--r-- | mm/memory.c | 13 |
3 files changed, 24 insertions, 3 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 58202c26c559..fc4415256ec3 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1350,6 +1350,7 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a #if USE_SPLIT_PTE_PTLOCKS #if ALLOC_SPLIT_PTLOCKS +void __init ptlock_cache_init(void); extern bool ptlock_alloc(struct page *page); extern void ptlock_free(struct page *page); @@ -1358,6 +1359,10 @@ static inline spinlock_t *ptlock_ptr(struct page *page) return page->ptl; } #else /* ALLOC_SPLIT_PTLOCKS */ +static inline void ptlock_cache_init(void) +{ +} + static inline bool ptlock_alloc(struct page *page) { return true; @@ -1410,10 +1415,17 @@ static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd) { return &mm->page_table_lock; } +static inline void ptlock_cache_init(void) {} static inline bool ptlock_init(struct page *page) { return true; } static inline void pte_lock_deinit(struct page *page) {} #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) { inc_zone_page_state(page, NR_PAGETABLE); diff --git a/init/main.c b/init/main.c index febc511e078a..01573fdfa186 100644 --- a/init/main.c +++ b/init/main.c @@ -476,7 +476,7 @@ static void __init mm_init(void) mem_init(); kmem_cache_init(); percpu_init_late(); - pgtable_cache_init(); + pgtable_init(); vmalloc_init(); } diff --git a/mm/memory.c b/mm/memory.c index e9c550484ba6..86487dfa5e59 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4275,11 +4275,20 @@ void copy_user_huge_page(struct page *dst, struct page *src, #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */ #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS + +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) { spinlock_t *ptl; - ptl = kmalloc(sizeof(spinlock_t), GFP_KERNEL); + ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL); if (!ptl) return false; page->ptl = ptl; @@ -4288,6 +4297,6 @@ bool ptlock_alloc(struct page *page) void ptlock_free(struct page *page) { - kfree(page->ptl); + kmem_cache_free(page_ptl_cachep, page->ptl); } #endif |