From e303297e6c3a7b847c4731eb14006ca6b435ecca Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 24 May 2011 17:12:01 -0700 Subject: mm: extended batches for generic mmu_gather Instead of using a single batch (the small on-stack, or an allocated page), try and extend the batch every time it runs out and only flush once either the extend fails or we're done. Signed-off-by: Peter Zijlstra Requested-by: Nick Piggin Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Hugh Dickins Cc: Benjamin Herrenschmidt Cc: David Miller Cc: Martin Schwidefsky Cc: Russell King Cc: Paul Mundt Cc: Jeff Dike Cc: Richard Weinberger Cc: Tony Luck Cc: Mel Gorman Cc: KOSAKI Motohiro Cc: Nick Piggin Cc: Namhyung Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-generic/tlb.h | 129 +++++++++++++++++++++++++++++----------------- mm/memory.c | 2 +- 2 files changed, 84 insertions(+), 47 deletions(-) diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h index 74f80f6b6cf..5a946a08ff9 100644 --- a/include/asm-generic/tlb.h +++ b/include/asm-generic/tlb.h @@ -19,16 +19,6 @@ #include #include -/* - * For UP we don't need to worry about TLB flush - * and page free order so much.. - */ -#ifdef CONFIG_SMP - #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U) -#else - #define tlb_fast_mode(tlb) 1 -#endif - #ifdef CONFIG_HAVE_RCU_TABLE_FREE /* * Semi RCU freeing of the page directories. @@ -78,6 +68,16 @@ extern void tlb_remove_table(struct mmu_gather *tlb, void *table); */ #define MMU_GATHER_BUNDLE 8 +struct mmu_gather_batch { + struct mmu_gather_batch *next; + unsigned int nr; + unsigned int max; + struct page *pages[0]; +}; + +#define MAX_GATHER_BATCH \ + ((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *)) + /* struct mmu_gather is an opaque type used by the mm code for passing around * any data needed by arch specific code for tlb_remove_page. */ @@ -86,22 +86,48 @@ struct mmu_gather { #ifdef CONFIG_HAVE_RCU_TABLE_FREE struct mmu_table_batch *batch; #endif - unsigned int nr; /* set to ~0U means fast mode */ - unsigned int max; /* nr < max */ - unsigned int need_flush;/* Really unmapped some ptes? */ - unsigned int fullmm; /* non-zero means full mm flush */ - struct page **pages; - struct page *local[MMU_GATHER_BUNDLE]; + unsigned int need_flush : 1, /* Did free PTEs */ + fast_mode : 1; /* No batching */ + + unsigned int fullmm; + + struct mmu_gather_batch *active; + struct mmu_gather_batch local; + struct page *__pages[MMU_GATHER_BUNDLE]; }; -static inline void __tlb_alloc_page(struct mmu_gather *tlb) +/* + * For UP we don't need to worry about TLB flush + * and page free order so much.. + */ +#ifdef CONFIG_SMP + #define tlb_fast_mode(tlb) (tlb->fast_mode) +#else + #define tlb_fast_mode(tlb) 1 +#endif + +static inline int tlb_next_batch(struct mmu_gather *tlb) { - unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); + struct mmu_gather_batch *batch; - if (addr) { - tlb->pages = (void *)addr; - tlb->max = PAGE_SIZE / sizeof(struct page *); + batch = tlb->active; + if (batch->next) { + tlb->active = batch->next; + return 1; } + + batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0); + if (!batch) + return 0; + + batch->next = NULL; + batch->nr = 0; + batch->max = MAX_GATHER_BATCH; + + tlb->active->next = batch; + tlb->active = batch; + + return 1; } /* tlb_gather_mmu @@ -114,16 +140,13 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm) { tlb->mm = mm; - tlb->max = ARRAY_SIZE(tlb->local); - tlb->pages = tlb->local; - - if (num_online_cpus() > 1) { - tlb->nr = 0; - __tlb_alloc_page(tlb); - } else /* Use fast mode if only one CPU is online */ - tlb->nr = ~0U; - - tlb->fullmm = fullmm; + tlb->fullmm = fullmm; + tlb->need_flush = 0; + tlb->fast_mode = (num_possible_cpus() == 1); + tlb->local.next = NULL; + tlb->local.nr = 0; + tlb->local.max = ARRAY_SIZE(tlb->__pages); + tlb->active = &tlb->local; #ifdef CONFIG_HAVE_RCU_TABLE_FREE tlb->batch = NULL; @@ -133,6 +156,8 @@ tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, bool fullmm) static inline void tlb_flush_mmu(struct mmu_gather *tlb) { + struct mmu_gather_batch *batch; + if (!tlb->need_flush) return; tlb->need_flush = 0; @@ -140,17 +165,15 @@ tlb_flush_mmu(struct mmu_gather *tlb) #ifdef CONFIG_HAVE_RCU_TABLE_FREE tlb_table_flush(tlb); #endif - if (!tlb_fast_mode(tlb)) { - free_pages_and_swap_cache(tlb->pages, tlb->nr); - tlb->nr = 0; - /* - * If we are using the local on-stack array of pages for MMU - * gather, try allocating an off-stack array again as we have - * recently freed pages. - */ - if (tlb->pages == tlb->local) - __tlb_alloc_page(tlb); + + if (tlb_fast_mode(tlb)) + return; + + for (batch = &tlb->local; batch; batch = batch->next) { + free_pages_and_swap_cache(batch->pages, batch->nr); + batch->nr = 0; } + tlb->active = &tlb->local; } /* tlb_finish_mmu @@ -160,13 +183,18 @@ tlb_flush_mmu(struct mmu_gather *tlb) static inline void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) { + struct mmu_gather_batch *batch, *next; + tlb_flush_mmu(tlb); /* keep the page table cache within bounds */ check_pgt_cache(); - if (tlb->pages != tlb->local) - free_pages((unsigned long)tlb->pages, 0); + for (batch = tlb->local.next; batch; batch = next) { + next = batch->next; + free_pages((unsigned long)batch, 0); + } + tlb->local.next = NULL; } /* __tlb_remove_page @@ -177,15 +205,24 @@ tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end) */ static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page) { + struct mmu_gather_batch *batch; + tlb->need_flush = 1; + if (tlb_fast_mode(tlb)) { free_page_and_swap_cache(page); return 1; /* avoid calling tlb_flush_mmu() */ } - tlb->pages[tlb->nr++] = page; - VM_BUG_ON(tlb->nr > tlb->max); - return tlb->max - tlb->nr; + batch = tlb->active; + batch->pages[batch->nr++] = page; + VM_BUG_ON(batch->nr > batch->max); + if (batch->nr == batch->max) { + if (!tlb_next_batch(tlb)) + return 0; + } + + return batch->max - batch->nr; } /* tlb_remove_page diff --git a/mm/memory.c b/mm/memory.c index a77fd23ee68..17193d74f30 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -994,8 +994,8 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb, spinlock_t *ptl; int rss[NR_MM_COUNTERS]; - init_rss_vec(rss); again: + init_rss_vec(rss); pte = pte_offset_map_lock(mm, pmd, addr, &ptl); arch_enter_lazy_mmu_mode(); do { -- cgit v1.2.3