Subject: [merged] mm-create-a-separate-slab-for-page-ptl-allocation-try-two.patch removed from -mm tree To: kirill.shutemov@xxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 22 Jan 2014 12:12:40 -0800 The patch titled Subject: mm: create a separate slab for page->ptl allocation has been removed from the -mm tree. Its filename was mm-create-a-separate-slab-for-page-ptl-allocation-try-two.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mm.h | 12 ++++++++++++ init/main.c | 2 +- mm/memory.c | 13 +++++++++++-- 3 files changed, 24 insertions(+), 3 deletions(-) diff -puN include/linux/mm.h~mm-create-a-separate-slab-for-page-ptl-allocation-try-two include/linux/mm.h --- a/include/linux/mm.h~mm-create-a-separate-slab-for-page-ptl-allocation-try-two +++ a/include/linux/mm.h @@ -1350,6 +1350,7 @@ static inline pmd_t *pmd_alloc(struct mm #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(str 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(st { 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 -puN init/main.c~mm-create-a-separate-slab-for-page-ptl-allocation-try-two init/main.c --- a/init/main.c~mm-create-a-separate-slab-for-page-ptl-allocation-try-two +++ a/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 -puN mm/memory.c~mm-create-a-separate-slab-for-page-ptl-allocation-try-two mm/memory.c --- a/mm/memory.c~mm-create-a-separate-slab-for-page-ptl-allocation-try-two +++ a/mm/memory.c @@ -4275,11 +4275,20 @@ void copy_user_huge_page(struct page *ds #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 _ Patches currently in -mm which might be from kirill.shutemov@xxxxxxxxxxxxxxx are origin.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html