From 0e39250845c0f91acc64264709b25f7f9b85c2c3 Mon Sep 17 00:00:00 2001 From: Alexander Duyck Date: Wed, 6 May 2015 21:11:51 -0700 Subject: [PATCH] net: Store virtual address instead of page in netdev_alloc_cache This change makes it so that we store the virtual address of the page in the netdev_alloc_cache instead of the page pointer. The idea behind this is to avoid multiple calls to page_address since the virtual address is required for every access, but the page pointer is only needed at allocation or reset of the page. While I was at it I also reordered the netdev_alloc_cache structure a bit so that the size is always 16 bytes by dropping size in the case where PAGE_SIZE is greater than or equal to 32KB. Signed-off-by: Alexander Duyck Signed-off-by: David S. Miller --- include/linux/skbuff.h | 5 ++-- net/core/skbuff.c | 55 ++++++++++++++++++++++++------------------ 2 files changed, 34 insertions(+), 26 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 9c2f793573fa..8b9a2c35a9d7 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2128,9 +2128,8 @@ static inline void __skb_queue_purge(struct sk_buff_head *list) kfree_skb(skb); } -#define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768) -#define NETDEV_FRAG_PAGE_MAX_SIZE (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER) -#define NETDEV_PAGECNT_MAX_BIAS NETDEV_FRAG_PAGE_MAX_SIZE +#define NETDEV_FRAG_PAGE_MAX_SIZE __ALIGN_MASK(32768, ~PAGE_MASK) +#define NETDEV_FRAG_PAGE_MAX_ORDER get_order(NETDEV_FRAG_PAGE_MAX_SIZE) void *netdev_alloc_frag(unsigned int fragsz); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index d6851ca32598..a3062ec341c3 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -348,7 +348,13 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size) EXPORT_SYMBOL(build_skb); struct netdev_alloc_cache { - struct page_frag frag; + void * va; +#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE) + __u16 offset; + __u16 size; +#else + __u32 offset; +#endif /* we maintain a pagecount bias, so that we dont dirty cache line * containing page->_count every time we allocate a fragment. */ @@ -361,21 +367,20 @@ static DEFINE_PER_CPU(struct netdev_alloc_cache, napi_alloc_cache); static struct page *__page_frag_refill(struct netdev_alloc_cache *nc, gfp_t gfp_mask) { - const unsigned int order = NETDEV_FRAG_PAGE_MAX_ORDER; struct page *page = NULL; gfp_t gfp = gfp_mask; - if (order) { - gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY | - __GFP_NOMEMALLOC; - page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, order); - nc->frag.size = PAGE_SIZE << (page ? order : 0); - } - +#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE) + gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY | + __GFP_NOMEMALLOC; + page = alloc_pages_node(NUMA_NO_NODE, gfp_mask, + NETDEV_FRAG_PAGE_MAX_ORDER); + nc->size = page ? NETDEV_FRAG_PAGE_MAX_SIZE : PAGE_SIZE; +#endif if (unlikely(!page)) page = alloc_pages_node(NUMA_NO_NODE, gfp, 0); - nc->frag.page = page; + nc->va = page ? page_address(page) : NULL; return page; } @@ -383,19 +388,20 @@ static struct page *__page_frag_refill(struct netdev_alloc_cache *nc, static void *__alloc_page_frag(struct netdev_alloc_cache *nc, unsigned int fragsz, gfp_t gfp_mask) { - struct page *page = nc->frag.page; - unsigned int size; + unsigned int size = PAGE_SIZE; + struct page *page; int offset; - if (unlikely(!page)) { + if (unlikely(!nc->va)) { refill: page = __page_frag_refill(nc, gfp_mask); if (!page) return NULL; - /* if size can vary use frag.size else just use PAGE_SIZE */ - size = NETDEV_FRAG_PAGE_MAX_ORDER ? nc->frag.size : PAGE_SIZE; - +#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE) + /* if size can vary use size else just use PAGE_SIZE */ + size = nc->size; +#endif /* Even if we own the page, we do not use atomic_set(). * This would break get_page_unless_zero() users. */ @@ -404,17 +410,20 @@ refill: /* reset page count bias and offset to start of new frag */ nc->pfmemalloc = page->pfmemalloc; nc->pagecnt_bias = size; - nc->frag.offset = size; + nc->offset = size; } - offset = nc->frag.offset - fragsz; + offset = nc->offset - fragsz; if (unlikely(offset < 0)) { + page = virt_to_page(nc->va); + if (!atomic_sub_and_test(nc->pagecnt_bias, &page->_count)) goto refill; - /* if size can vary use frag.size else just use PAGE_SIZE */ - size = NETDEV_FRAG_PAGE_MAX_ORDER ? nc->frag.size : PAGE_SIZE; - +#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE) + /* if size can vary use size else just use PAGE_SIZE */ + size = nc->size; +#endif /* OK, page count is 0, we can safely set it */ atomic_set(&page->_count, size); @@ -424,9 +433,9 @@ refill: } nc->pagecnt_bias--; - nc->frag.offset = offset; + nc->offset = offset; - return page_address(page) + offset; + return nc->va + offset; } static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask) -- 2.20.1