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Fri, 23 Aug 2024 23:06:46 +0800 (CST) Received: from localhost.localdomain (10.90.30.45) by dggpemf200006.china.huawei.com (7.185.36.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Fri, 23 Aug 2024 23:06:46 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Alexander Duyck , Andrew Morton , Subject: [PATCH net-next v14 05/11] mm: page_frag: reuse existing space for 'size' and 'pfmemalloc' Date: Fri, 23 Aug 2024 23:00:33 +0800 Message-ID: <20240823150040.1567062-6-linyunsheng@huawei.com> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20240823150040.1567062-1-linyunsheng@huawei.com> References: <20240823150040.1567062-1-linyunsheng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.90.30.45] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpemf200006.china.huawei.com (7.185.36.61) X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: AD42C1C0018 X-Stat-Signature: 9tt3rh9pthzi8aeqb54m75buoq1twcma X-HE-Tag: 1724425609-548746 X-HE-Meta: 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 4l1BP9e6 3s1FTY2lLYZPecwp7g6RDzDDn4QDG+wkDKPjNAbB5XJFYXmGjaGpcO7vR5gbvx+H7ZuG6VQ7ZuRjD0TSVkUQ3YgGDe+0NJuuOtTdAMn6FWprBcAxLJDTzlUz502PXAcwHYbi1JIPA/0dS1PUfy7WjJjFCSFdD0XyNnfvxf0DizrtyplT4Nb+vC/3MEs33nMNUeE2eJy1TH0ylFc2VCfHA5yjJHnVyM5ZZYLvxGOjBBlJfbgZ20NlBFz7RHK/14FzGhxgOP0MJohggvgLDbHbPjTLDHoTkRKYz2xVJ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Currently there is one 'struct page_frag' for every 'struct sock' and 'struct task_struct', we are about to replace the 'struct page_frag' with 'struct page_frag_cache' for them. Before begin the replacing, we need to ensure the size of 'struct page_frag_cache' is not bigger than the size of 'struct page_frag', as there may be tens of thousands of 'struct sock' and 'struct task_struct' instances in the system. By or'ing the page order & pfmemalloc with lower bits of 'va' instead of using 'u16' or 'u32' for page size and 'u8' for pfmemalloc, we are able to avoid 3 or 5 bytes space waste. And page address & pfmemalloc & order is unchanged for the same page in the same 'page_frag_cache' instance, it makes sense to fit them together. After this patch, the size of 'struct page_frag_cache' should be the same as the size of 'struct page_frag'. CC: Alexander Duyck Signed-off-by: Yunsheng Lin --- include/linux/mm_types_task.h | 19 ++++--- include/linux/page_frag_cache.h | 98 +++++++++++++++++++++++++++++++-- mm/page_frag_cache.c | 64 +++++++++++---------- 3 files changed, 140 insertions(+), 41 deletions(-) diff --git a/include/linux/mm_types_task.h b/include/linux/mm_types_task.h index cdc1e3696439..a8635460e027 100644 --- a/include/linux/mm_types_task.h +++ b/include/linux/mm_types_task.h @@ -50,18 +50,21 @@ struct page_frag { #define PAGE_FRAG_CACHE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK) #define PAGE_FRAG_CACHE_MAX_ORDER get_order(PAGE_FRAG_CACHE_MAX_SIZE) struct page_frag_cache { - void *va; -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) + /* encoded_page consists of the virtual address, pfmemalloc bit and order + * of a page. + */ + unsigned long encoded_page; + + /* we maintain a pagecount bias, so that we dont dirty cache line + * containing page->_refcount every time we allocate a fragment. + */ +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) && (BITS_PER_LONG <= 32) __u16 offset; - __u16 size; + __u16 pagecnt_bias; #else __u32 offset; + __u32 pagecnt_bias; #endif - /* we maintain a pagecount bias, so that we dont dirty cache line - * containing page->_refcount every time we allocate a fragment. - */ - unsigned int pagecnt_bias; - bool pfmemalloc; }; /* Track pages that require TLB flushes */ diff --git a/include/linux/page_frag_cache.h b/include/linux/page_frag_cache.h index 0a52f7a179c8..1ed0d1b7014b 100644 --- a/include/linux/page_frag_cache.h +++ b/include/linux/page_frag_cache.h @@ -3,24 +3,114 @@ #ifndef _LINUX_PAGE_FRAG_CACHE_H #define _LINUX_PAGE_FRAG_CACHE_H +#include +#include #include +#include #include #include +#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) +/* Use a full byte here to enable assembler optimization as the shift + * operation is usually expecting a byte. + */ +#define PAGE_FRAG_CACHE_ORDER_MASK GENMASK(7, 0) +#define PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT 8 +#define PAGE_FRAG_CACHE_PFMEMALLOC_BIT BIT(PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT) +#else +/* Compiler should be able to figure out we don't read things as any value + * ANDed with 0 is 0. + */ +#define PAGE_FRAG_CACHE_ORDER_MASK 0 +#define PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT 0 +#define PAGE_FRAG_CACHE_PFMEMALLOC_BIT BIT(PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT) +#endif + +static inline unsigned long page_pool_encode_page(struct page *page, + unsigned int order, + bool pfmemalloc) +{ + BUILD_BUG_ON(PAGE_FRAG_CACHE_MAX_ORDER > PAGE_FRAG_CACHE_ORDER_MASK); + BUILD_BUG_ON(PAGE_FRAG_CACHE_PFMEMALLOC_BIT >= PAGE_SIZE); + + return (unsigned long)page_address(page) | + (order & PAGE_FRAG_CACHE_ORDER_MASK) | + ((unsigned long)pfmemalloc << PAGE_FRAG_CACHE_PFMEMALLOC_SHIFT); +} + +static inline unsigned long page_pool_encoded_page_order(unsigned long encoded_page) +{ + return encoded_page & PAGE_FRAG_CACHE_ORDER_MASK; +} + +static inline bool page_pool_encoded_page_pfmemalloc(unsigned long encoded_page) +{ + return !!(encoded_page & PAGE_FRAG_CACHE_PFMEMALLOC_BIT); +} + +static inline void *page_pool_encoded_page_address(unsigned long encoded_page) +{ + return (void *)(encoded_page & PAGE_MASK); +} + +static inline struct page *page_pool_encoded_page_ptr(unsigned long encoded_page) +{ + return virt_to_page((void *)encoded_page); +} + static inline void page_frag_cache_init(struct page_frag_cache *nc) { - nc->va = NULL; + nc->encoded_page = 0; } static inline bool page_frag_cache_is_pfmemalloc(struct page_frag_cache *nc) { - return !!nc->pfmemalloc; + return page_pool_encoded_page_pfmemalloc(nc->encoded_page); +} + +static inline unsigned int page_frag_cache_page_size(unsigned long encoded_page) +{ + return PAGE_SIZE << page_pool_encoded_page_order(encoded_page); } void page_frag_cache_drain(struct page_frag_cache *nc); void __page_frag_cache_drain(struct page *page, unsigned int count); -void *__page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz, - gfp_t gfp_mask, unsigned int align_mask); +void *__page_frag_cache_prepare(struct page_frag_cache *nc, unsigned int fragsz, + struct page_frag *pfrag, gfp_t gfp_mask, + unsigned int align_mask); + +static inline void __page_frag_cache_commit(struct page_frag_cache *nc, + struct page_frag *pfrag, bool referenced, + unsigned int used_sz) +{ + if (referenced) { + VM_BUG_ON(!nc->pagecnt_bias); + nc->pagecnt_bias--; + } + + /* Committed offset might be bigger than the current offset due to alignment */ + VM_BUG_ON(nc->offset > pfrag->offset); + + VM_BUG_ON(used_sz > pfrag->size); + VM_BUG_ON(pfrag->offset + pfrag->size > page_frag_cache_page_size(nc->encoded_page)); + + nc->offset = pfrag->offset + used_sz; +} + +static inline void *__page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz, + gfp_t gfp_mask, unsigned int align_mask) +{ + struct page_frag page_frag; + void *va; + + va = __page_frag_cache_prepare(nc, fragsz, &page_frag, gfp_mask, align_mask); + if (unlikely(!va)) + return NULL; + + __page_frag_cache_commit(nc, &page_frag, true, fragsz); + + return va; +} static inline void *page_frag_alloc_align(struct page_frag_cache *nc, unsigned int fragsz, gfp_t gfp_mask, diff --git a/mm/page_frag_cache.c b/mm/page_frag_cache.c index 4c8e04379cb3..2865bff7199d 100644 --- a/mm/page_frag_cache.c +++ b/mm/page_frag_cache.c @@ -22,6 +22,7 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, gfp_t gfp_mask) { + unsigned long order = PAGE_FRAG_CACHE_MAX_ORDER; struct page *page = NULL; gfp_t gfp = gfp_mask; @@ -30,23 +31,31 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC; page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, PAGE_FRAG_CACHE_MAX_ORDER); - nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE; #endif - if (unlikely(!page)) + if (unlikely(!page)) { page = alloc_pages_node(NUMA_NO_NODE, gfp, 0); + if (unlikely(!page)) { + nc->encoded_page = 0; + return NULL; + } + + order = 0; + } - nc->va = page ? page_address(page) : NULL; + nc->encoded_page = page_pool_encode_page(page, order, + page_is_pfmemalloc(page)); return page; } void page_frag_cache_drain(struct page_frag_cache *nc) { - if (!nc->va) + if (!nc->encoded_page) return; - __page_frag_cache_drain(virt_to_head_page(nc->va), nc->pagecnt_bias); - nc->va = NULL; + __page_frag_cache_drain(page_pool_encoded_page_ptr(nc->encoded_page), + nc->pagecnt_bias); + nc->encoded_page = 0; } EXPORT_SYMBOL(page_frag_cache_drain); @@ -59,35 +68,32 @@ void __page_frag_cache_drain(struct page *page, unsigned int count) } EXPORT_SYMBOL(__page_frag_cache_drain); -void *__page_frag_alloc_align(struct page_frag_cache *nc, - unsigned int fragsz, gfp_t gfp_mask, - unsigned int align_mask) +void *__page_frag_cache_prepare(struct page_frag_cache *nc, unsigned int fragsz, + struct page_frag *pfrag, gfp_t gfp_mask, + unsigned int align_mask) { -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - unsigned int size = nc->size; -#else - unsigned int size = PAGE_SIZE; -#endif - unsigned int offset; + unsigned long encoded_page = nc->encoded_page; + unsigned int size, offset; struct page *page; - if (unlikely(!nc->va)) { + size = page_frag_cache_page_size(encoded_page); + page = page_pool_encoded_page_ptr(encoded_page); + + if (unlikely(!encoded_page)) { refill: page = __page_frag_cache_refill(nc, gfp_mask); if (!page) return NULL; -#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE) - /* if size can vary use size else just use PAGE_SIZE */ - size = nc->size; -#endif + encoded_page = nc->encoded_page; + size = page_frag_cache_page_size(encoded_page); + /* Even if we own the page, we do not use atomic_set(). * This would break get_page_unless_zero() users. */ page_ref_add(page, PAGE_FRAG_CACHE_MAX_SIZE); /* reset page count bias and offset to start of new frag */ - nc->pfmemalloc = page_is_pfmemalloc(page); nc->pagecnt_bias = PAGE_FRAG_CACHE_MAX_SIZE + 1; nc->offset = 0; } @@ -107,13 +113,12 @@ void *__page_frag_alloc_align(struct page_frag_cache *nc, return NULL; } - page = virt_to_page(nc->va); - if (!page_ref_sub_and_test(page, nc->pagecnt_bias)) goto refill; - if (unlikely(nc->pfmemalloc)) { - free_unref_page(page, compound_order(page)); + if (unlikely(page_pool_encoded_page_pfmemalloc(encoded_page))) { + free_unref_page(page, + page_pool_encoded_page_order(encoded_page)); goto refill; } @@ -125,12 +130,13 @@ void *__page_frag_alloc_align(struct page_frag_cache *nc, offset = 0; } - nc->pagecnt_bias--; - nc->offset = offset + fragsz; + pfrag->page = page; + pfrag->offset = offset; + pfrag->size = size - offset; - return nc->va + offset; + return page_pool_encoded_page_address(encoded_page) + offset; } -EXPORT_SYMBOL(__page_frag_alloc_align); +EXPORT_SYMBOL(__page_frag_cache_prepare); /* * Frees a page fragment allocated out of either a compound or order 0 page.