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Diffstat (limited to '')
| -rw-r--r-- | include/net/page_pool.h | 386 |
1 files changed, 386 insertions, 0 deletions
diff --git a/include/net/page_pool.h b/include/net/page_pool.h new file mode 100644 index 000000000..ad0bafc87 --- /dev/null +++ b/include/net/page_pool.h @@ -0,0 +1,386 @@ +/* SPDX-License-Identifier: GPL-2.0 + * + * page_pool.h + * Author: Jesper Dangaard Brouer <netoptimizer@brouer.com> + * Copyright (C) 2016 Red Hat, Inc. + */ + +/** + * DOC: page_pool allocator + * + * This page_pool allocator is optimized for the XDP mode that + * uses one-frame-per-page, but have fallbacks that act like the + * regular page allocator APIs. + * + * Basic use involve replacing alloc_pages() calls with the + * page_pool_alloc_pages() call. Drivers should likely use + * page_pool_dev_alloc_pages() replacing dev_alloc_pages(). + * + * API keeps track of in-flight pages, in-order to let API user know + * when it is safe to dealloactor page_pool object. Thus, API users + * must make sure to call page_pool_release_page() when a page is + * "leaving" the page_pool. Or call page_pool_put_page() where + * appropiate. For maintaining correct accounting. + * + * API user must only call page_pool_put_page() once on a page, as it + * will either recycle the page, or in case of elevated refcnt, it + * will release the DMA mapping and in-flight state accounting. We + * hope to lift this requirement in the future. + */ +#ifndef _NET_PAGE_POOL_H +#define _NET_PAGE_POOL_H + +#include <linux/mm.h> /* Needed by ptr_ring */ +#include <linux/ptr_ring.h> +#include <linux/dma-direction.h> + +#define PP_FLAG_DMA_MAP BIT(0) /* Should page_pool do the DMA + * map/unmap + */ +#define PP_FLAG_DMA_SYNC_DEV BIT(1) /* If set all pages that the driver gets + * from page_pool will be + * DMA-synced-for-device according to + * the length provided by the device + * driver. + * Please note DMA-sync-for-CPU is still + * device driver responsibility + */ +#define PP_FLAG_PAGE_FRAG BIT(2) /* for page frag feature */ +#define PP_FLAG_ALL (PP_FLAG_DMA_MAP |\ + PP_FLAG_DMA_SYNC_DEV |\ + PP_FLAG_PAGE_FRAG) + +/* + * Fast allocation side cache array/stack + * + * The cache size and refill watermark is related to the network + * use-case. The NAPI budget is 64 packets. After a NAPI poll the RX + * ring is usually refilled and the max consumed elements will be 64, + * thus a natural max size of objects needed in the cache. + * + * Keeping room for more objects, is due to XDP_DROP use-case. As + * XDP_DROP allows the opportunity to recycle objects directly into + * this array, as it shares the same softirq/NAPI protection. If + * cache is already full (or partly full) then the XDP_DROP recycles + * would have to take a slower code path. + */ +#define PP_ALLOC_CACHE_SIZE 128 +#define PP_ALLOC_CACHE_REFILL 64 +struct pp_alloc_cache { + u32 count; + struct page *cache[PP_ALLOC_CACHE_SIZE]; +}; + +struct page_pool_params { + unsigned int flags; + unsigned int order; + unsigned int pool_size; + int nid; /* Numa node id to allocate from pages from */ + struct device *dev; /* device, for DMA pre-mapping purposes */ + enum dma_data_direction dma_dir; /* DMA mapping direction */ + unsigned int max_len; /* max DMA sync memory size */ + unsigned int offset; /* DMA addr offset */ + void (*init_callback)(struct page *page, void *arg); + void *init_arg; +}; + +#ifdef CONFIG_PAGE_POOL_STATS +struct page_pool_alloc_stats { + u64 fast; /* fast path allocations */ + u64 slow; /* slow-path order 0 allocations */ + u64 slow_high_order; /* slow-path high order allocations */ + u64 empty; /* failed refills due to empty ptr ring, forcing + * slow path allocation + */ + u64 refill; /* allocations via successful refill */ + u64 waive; /* failed refills due to numa zone mismatch */ +}; + +struct page_pool_recycle_stats { + u64 cached; /* recycling placed page in the cache. */ + u64 cache_full; /* cache was full */ + u64 ring; /* recycling placed page back into ptr ring */ + u64 ring_full; /* page was released from page-pool because + * PTR ring was full. + */ + u64 released_refcnt; /* page released because of elevated + * refcnt + */ +}; + +/* This struct wraps the above stats structs so users of the + * page_pool_get_stats API can pass a single argument when requesting the + * stats for the page pool. + */ +struct page_pool_stats { + struct page_pool_alloc_stats alloc_stats; + struct page_pool_recycle_stats recycle_stats; +}; + +int page_pool_ethtool_stats_get_count(void); +u8 *page_pool_ethtool_stats_get_strings(u8 *data); +u64 *page_pool_ethtool_stats_get(u64 *data, void *stats); + +/* + * Drivers that wish to harvest page pool stats and report them to users + * (perhaps via ethtool, debugfs, or another mechanism) can allocate a + * struct page_pool_stats call page_pool_get_stats to get stats for the specified pool. + */ +bool page_pool_get_stats(struct page_pool *pool, + struct page_pool_stats *stats); +#else + +static inline int page_pool_ethtool_stats_get_count(void) +{ + return 0; +} + +static inline u8 *page_pool_ethtool_stats_get_strings(u8 *data) +{ + return data; +} + +static inline u64 *page_pool_ethtool_stats_get(u64 *data, void *stats) +{ + return data; +} + +#endif + +struct page_pool { + struct page_pool_params p; + + struct delayed_work release_dw; + void (*disconnect)(void *); + unsigned long defer_start; + unsigned long defer_warn; + + u32 pages_state_hold_cnt; + unsigned int frag_offset; + struct page *frag_page; + long frag_users; + +#ifdef CONFIG_PAGE_POOL_STATS + /* these stats are incremented while in softirq context */ + struct page_pool_alloc_stats alloc_stats; +#endif + u32 xdp_mem_id; + + /* + * Data structure for allocation side + * + * Drivers allocation side usually already perform some kind + * of resource protection. Piggyback on this protection, and + * require driver to protect allocation side. + * + * For NIC drivers this means, allocate a page_pool per + * RX-queue. As the RX-queue is already protected by + * Softirq/BH scheduling and napi_schedule. NAPI schedule + * guarantee that a single napi_struct will only be scheduled + * on a single CPU (see napi_schedule). + */ + struct pp_alloc_cache alloc ____cacheline_aligned_in_smp; + + /* Data structure for storing recycled pages. + * + * Returning/freeing pages is more complicated synchronization + * wise, because free's can happen on remote CPUs, with no + * association with allocation resource. + * + * Use ptr_ring, as it separates consumer and producer + * effeciently, it a way that doesn't bounce cache-lines. + * + * TODO: Implement bulk return pages into this structure. + */ + struct ptr_ring ring; + +#ifdef CONFIG_PAGE_POOL_STATS + /* recycle stats are per-cpu to avoid locking */ + struct page_pool_recycle_stats __percpu *recycle_stats; +#endif + atomic_t pages_state_release_cnt; + + /* A page_pool is strictly tied to a single RX-queue being + * protected by NAPI, due to above pp_alloc_cache. This + * refcnt serves purpose is to simplify drivers error handling. + */ + refcount_t user_cnt; + + u64 destroy_cnt; +}; + +struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); + +static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool) +{ + gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN); + + return page_pool_alloc_pages(pool, gfp); +} + +struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *offset, + unsigned int size, gfp_t gfp); + +static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool, + unsigned int *offset, + unsigned int size) +{ + gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN); + + return page_pool_alloc_frag(pool, offset, size, gfp); +} + +/* get the stored dma direction. A driver might decide to treat this locally and + * avoid the extra cache line from page_pool to determine the direction + */ +static +inline enum dma_data_direction page_pool_get_dma_dir(struct page_pool *pool) +{ + return pool->p.dma_dir; +} + +bool page_pool_return_skb_page(struct page *page); + +struct page_pool *page_pool_create(const struct page_pool_params *params); + +struct xdp_mem_info; + +#ifdef CONFIG_PAGE_POOL +void page_pool_destroy(struct page_pool *pool); +void page_pool_use_xdp_mem(struct page_pool *pool, void (*disconnect)(void *), + struct xdp_mem_info *mem); +void page_pool_release_page(struct page_pool *pool, struct page *page); +void page_pool_put_page_bulk(struct page_pool *pool, void **data, + int count); +#else +static inline void page_pool_destroy(struct page_pool *pool) +{ +} + +static inline void page_pool_use_xdp_mem(struct page_pool *pool, + void (*disconnect)(void *), + struct xdp_mem_info *mem) +{ +} +static inline void page_pool_release_page(struct page_pool *pool, + struct page *page) +{ +} + +static inline void page_pool_put_page_bulk(struct page_pool *pool, void **data, + int count) +{ +} +#endif + +void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, + unsigned int dma_sync_size, + bool allow_direct); + +static inline void page_pool_fragment_page(struct page *page, long nr) +{ + atomic_long_set(&page->pp_frag_count, nr); +} + +static inline long page_pool_defrag_page(struct page *page, long nr) +{ + long ret; + + /* If nr == pp_frag_count then we have cleared all remaining + * references to the page. No need to actually overwrite it, instead + * we can leave this to be overwritten by the calling function. + * + * The main advantage to doing this is that an atomic_read is + * generally a much cheaper operation than an atomic update, + * especially when dealing with a page that may be partitioned + * into only 2 or 3 pieces. + */ + if (atomic_long_read(&page->pp_frag_count) == nr) + return 0; + + ret = atomic_long_sub_return(nr, &page->pp_frag_count); + WARN_ON(ret < 0); + return ret; +} + +static inline bool page_pool_is_last_frag(struct page_pool *pool, + struct page *page) +{ + /* If fragments aren't enabled or count is 0 we were the last user */ + return !(pool->p.flags & PP_FLAG_PAGE_FRAG) || + (page_pool_defrag_page(page, 1) == 0); +} + +static inline void page_pool_put_page(struct page_pool *pool, + struct page *page, + unsigned int dma_sync_size, + bool allow_direct) +{ + /* When page_pool isn't compiled-in, net/core/xdp.c doesn't + * allow registering MEM_TYPE_PAGE_POOL, but shield linker. + */ +#ifdef CONFIG_PAGE_POOL + if (!page_pool_is_last_frag(pool, page)) + return; + + page_pool_put_defragged_page(pool, page, dma_sync_size, allow_direct); +#endif +} + +/* Same as above but will try to sync the entire area pool->max_len */ +static inline void page_pool_put_full_page(struct page_pool *pool, + struct page *page, bool allow_direct) +{ + page_pool_put_page(pool, page, -1, allow_direct); +} + +/* Same as above but the caller must guarantee safe context. e.g NAPI */ +static inline void page_pool_recycle_direct(struct page_pool *pool, + struct page *page) +{ + page_pool_put_full_page(pool, page, true); +} + +#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \ + (sizeof(dma_addr_t) > sizeof(unsigned long)) + +static inline dma_addr_t page_pool_get_dma_addr(struct page *page) +{ + dma_addr_t ret = page->dma_addr; + + if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) + ret |= (dma_addr_t)page->dma_addr_upper << 16 << 16; + + return ret; +} + +static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr) +{ + page->dma_addr = addr; + if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) + page->dma_addr_upper = upper_32_bits(addr); +} + +static inline bool is_page_pool_compiled_in(void) +{ +#ifdef CONFIG_PAGE_POOL + return true; +#else + return false; +#endif +} + +static inline bool page_pool_put(struct page_pool *pool) +{ + return refcount_dec_and_test(&pool->user_cnt); +} + +/* Caller must provide appropriate safe context, e.g. NAPI. */ +void page_pool_update_nid(struct page_pool *pool, int new_nid); +static inline void page_pool_nid_changed(struct page_pool *pool, int new_nid) +{ + if (unlikely(pool->p.nid != new_nid)) + page_pool_update_nid(pool, new_nid); +} + +#endif /* _NET_PAGE_POOL_H */ |