diff options
| -rw-r--r-- | Documentation/networking/page_pool.rst | 92 | ||||
| -rw-r--r-- | include/net/page_pool.h | 134 | ||||
| -rw-r--r-- | net/core/page_pool.c | 31 |
3 files changed, 155 insertions, 102 deletions
diff --git a/Documentation/networking/page_pool.rst b/Documentation/networking/page_pool.rst index eb96a592ec6b..53b5448cc0f1 100644 --- a/Documentation/networking/page_pool.rst +++ b/Documentation/networking/page_pool.rst @@ -64,50 +64,19 @@ This lockless guarantee naturally comes from running under a NAPI softirq. The protection doesn't strictly have to be NAPI, any guarantee that allocating a page will cause no race conditions is enough. -* page_pool_create(): Create a pool. - * flags: PP_FLAG_DMA_MAP, PP_FLAG_DMA_SYNC_DEV - * order: 2^order pages on allocation - * pool_size: size of the ptr_ring - * nid: preferred NUMA node for allocation - * dev: struct device. Used on DMA operations - * dma_dir: DMA direction - * max_len: max DMA sync memory size - * offset: DMA address offset - -* page_pool_put_page(): The outcome of this depends on the page refcnt. If the - driver bumps the refcnt > 1 this will unmap the page. If the page refcnt is 1 - the allocator owns the page and will try to recycle it in one of the pool - caches. If PP_FLAG_DMA_SYNC_DEV is set, the page will be synced for_device - using dma_sync_single_range_for_device(). - -* page_pool_put_full_page(): Similar to page_pool_put_page(), but will DMA sync - for the entire memory area configured in area pool->max_len. - -* page_pool_recycle_direct(): Similar to page_pool_put_full_page() but caller - must guarantee safe context (e.g NAPI), since it will recycle the page - directly into the pool fast cache. - -* page_pool_dev_alloc_pages(): Get a page from the page allocator or page_pool - caches. - -* page_pool_get_dma_addr(): Retrieve the stored DMA address. - -* page_pool_get_dma_dir(): Retrieve the stored DMA direction. - -* page_pool_put_page_bulk(): Tries to refill a number of pages into the - ptr_ring cache holding ptr_ring producer lock. If the ptr_ring is full, - page_pool_put_page_bulk() will release leftover pages to the page allocator. - page_pool_put_page_bulk() is suitable to be run inside the driver NAPI tx - completion loop for the XDP_REDIRECT use case. - Please note the caller must not use data area after running - page_pool_put_page_bulk(), as this function overwrites it. - -* page_pool_get_stats(): Retrieve statistics about the page_pool. This API - is only available if the kernel has been configured with - ``CONFIG_PAGE_POOL_STATS=y``. A pointer to a caller allocated ``struct - page_pool_stats`` structure is passed to this API which is filled in. The - caller can then report those stats to the user (perhaps via ethtool, - debugfs, etc.). See below for an example usage of this API. +.. kernel-doc:: net/core/page_pool.c + :identifiers: page_pool_create + +.. kernel-doc:: include/net/page_pool.h + :identifiers: struct page_pool_params + +.. kernel-doc:: include/net/page_pool.h + :identifiers: page_pool_put_page page_pool_put_full_page + page_pool_recycle_direct page_pool_dev_alloc_pages + page_pool_get_dma_addr page_pool_get_dma_dir + +.. kernel-doc:: net/core/page_pool.c + :identifiers: page_pool_put_page_bulk page_pool_get_stats DMA sync -------- @@ -146,36 +115,17 @@ with fragmented page pools. Stats API and structures ------------------------ If the kernel is configured with ``CONFIG_PAGE_POOL_STATS=y``, the API -``page_pool_get_stats()`` and structures described below are available. It -takes a pointer to a ``struct page_pool`` and a pointer to a ``struct -page_pool_stats`` allocated by the caller. +page_pool_get_stats() and structures described below are available. +It takes a pointer to a ``struct page_pool`` and a pointer to a struct +page_pool_stats allocated by the caller. -The API will fill in the provided ``struct page_pool_stats`` with +The API will fill in the provided struct page_pool_stats with statistics about the page_pool. -The stats structure has the following fields:: - - struct page_pool_stats { - struct page_pool_alloc_stats alloc_stats; - struct page_pool_recycle_stats recycle_stats; - }; - - -The ``struct page_pool_alloc_stats`` has the following fields: - * ``fast``: successful fast path allocations - * ``slow``: slow path order-0 allocations - * ``slow_high_order``: slow path high order allocations - * ``empty``: ptr ring is empty, so a slow path allocation was forced. - * ``refill``: an allocation which triggered a refill of the cache - * ``waive``: pages obtained from the ptr ring that cannot be added to - the cache due to a NUMA mismatch. - -The ``struct page_pool_recycle_stats`` has the following fields: - * ``cached``: recycling placed page in the page pool cache - * ``cache_full``: page pool cache was full - * ``ring``: page placed into the ptr ring - * ``ring_full``: page released from page pool because the ptr ring was full - * ``released_refcnt``: page released (and not recycled) because refcnt > 1 +.. kernel-doc:: include/net/page_pool.h + :identifiers: struct page_pool_recycle_stats + struct page_pool_alloc_stats + struct page_pool_stats Coding examples =============== diff --git a/include/net/page_pool.h b/include/net/page_pool.h index f1d5cc1fa13b..73d4f786418d 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -70,47 +70,76 @@ struct pp_alloc_cache { struct page *cache[PP_ALLOC_CACHE_SIZE]; }; +/** + * struct page_pool_params - page pool parameters + * @flags: PP_FLAG_DMA_MAP, PP_FLAG_DMA_SYNC_DEV, PP_FLAG_PAGE_FRAG + * @order: 2^order pages on allocation + * @pool_size: size of the ptr_ring + * @nid: NUMA node id to allocate from pages from + * @dev: device, for DMA pre-mapping purposes + * @napi: NAPI which is the sole consumer of pages, otherwise NULL + * @dma_dir: DMA mapping direction + * @max_len: max DMA sync memory size for PP_FLAG_DMA_SYNC_DEV + * @offset: DMA sync address offset for PP_FLAG_DMA_SYNC_DEV + */ 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 */ - struct napi_struct *napi; /* Sole consumer of pages, otherwise NULL */ - enum dma_data_direction dma_dir; /* DMA mapping direction */ - unsigned int max_len; /* max DMA sync memory size */ - unsigned int offset; /* DMA addr offset */ + int nid; + struct device *dev; + struct napi_struct *napi; + enum dma_data_direction dma_dir; + unsigned int max_len; + unsigned int offset; +/* private: used by test code only */ void (*init_callback)(struct page *page, void *arg); void *init_arg; }; #ifdef CONFIG_PAGE_POOL_STATS +/** + * struct page_pool_alloc_stats - allocation statistics + * @fast: successful fast path allocations + * @slow: slow path order-0 allocations + * @slow_high_order: slow path high order allocations + * @empty: ptr ring is empty, so a slow path allocation was forced + * @refill: an allocation which triggered a refill of the cache + * @waive: pages obtained from the ptr ring that cannot be added to + * the cache due to a NUMA mismatch + */ 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 */ + u64 fast; + u64 slow; + u64 slow_high_order; + u64 empty; + u64 refill; + u64 waive; }; +/** + * struct page_pool_recycle_stats - recycling (freeing) statistics + * @cached: recycling placed page in the page pool cache + * @cache_full: page pool cache was full + * @ring: page placed into the ptr ring + * @ring_full: page released from page pool because the ptr ring was full + * @released_refcnt: page released (and not recycled) because refcnt > 1 + */ 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 - */ + u64 cached; + u64 cache_full; + u64 ring; + u64 ring_full; + u64 released_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 - combined page pool use statistics + * @alloc_stats: see struct page_pool_alloc_stats + * @recycle_stats: see struct page_pool_recycle_stats + * + * Wrapper struct for combining page pool stats with different storage + * requirements. */ struct page_pool_stats { struct page_pool_alloc_stats alloc_stats; @@ -211,6 +240,12 @@ struct page_pool { struct page *page_pool_alloc_pages(struct page_pool *pool, gfp_t gfp); +/** + * page_pool_dev_alloc_pages() - allocate a page. + * @pool: pool from which to allocate + * + * Get a page from the page allocator or page_pool caches. + */ static inline struct page *page_pool_dev_alloc_pages(struct page_pool *pool) { gfp_t gfp = (GFP_ATOMIC | __GFP_NOWARN); @@ -230,8 +265,12 @@ static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool, 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 +/** + * page_pool_get_dma_dir() - Retrieve the stored DMA direction. + * @pool: pool from which page was allocated + * + * Get the stored dma direction. A driver might decide to store 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) @@ -321,6 +360,19 @@ static inline bool page_pool_is_last_frag(struct page_pool *pool, (page_pool_defrag_page(page, 1) == 0); } +/** + * page_pool_put_page() - release a reference to a page pool page + * @pool: pool from which page was allocated + * @page: page to release a reference on + * @dma_sync_size: how much of the page may have been touched by the device + * @allow_direct: released by the consumer, allow lockless caching + * + * The outcome of this depends on the page refcnt. If the driver bumps + * the refcnt > 1 this will unmap the page. If the page refcnt is 1 + * the allocator owns the page and will try to recycle it in one of the pool + * caches. If PP_FLAG_DMA_SYNC_DEV is set, the page will be synced for_device + * using dma_sync_single_range_for_device(). + */ static inline void page_pool_put_page(struct page_pool *pool, struct page *page, unsigned int dma_sync_size, @@ -337,14 +389,29 @@ static inline void page_pool_put_page(struct page_pool *pool, #endif } -/* Same as above but will try to sync the entire area pool->max_len */ +/** + * page_pool_put_full_page() - release a reference on a page pool page + * @pool: pool from which page was allocated + * @page: page to release a reference on + * @allow_direct: released by the consumer, allow lockless caching + * + * Similar to page_pool_put_page(), but will DMA sync the entire memory area + * as configured in &page_pool_params.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 */ +/** + * page_pool_recycle_direct() - release a reference on a page pool page + * @pool: pool from which page was allocated + * @page: page to release a reference on + * + * Similar to page_pool_put_full_page() but caller must guarantee safe context + * (e.g NAPI), since it will recycle the page directly into the pool fast cache. + */ static inline void page_pool_recycle_direct(struct page_pool *pool, struct page *page) { @@ -354,6 +421,13 @@ static inline void page_pool_recycle_direct(struct page_pool *pool, #define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \ (sizeof(dma_addr_t) > sizeof(unsigned long)) +/** + * page_pool_get_dma_addr() - Retrieve the stored DMA address. + * @page: page allocated from a page pool + * + * Fetch the DMA address of the page. The page pool to which the page belongs + * must had been created with PP_FLAG_DMA_MAP. + */ static inline dma_addr_t page_pool_get_dma_addr(struct page *page) { dma_addr_t ret = page->dma_addr; diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 7ca456bfab71..5d615a169718 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -58,6 +58,17 @@ static const char pp_stats[][ETH_GSTRING_LEN] = { "rx_pp_recycle_released_ref", }; +/** + * page_pool_get_stats() - fetch page pool stats + * @pool: pool from which page was allocated + * @stats: struct page_pool_stats to fill in + * + * Retrieve statistics about the page_pool. This API is only available + * if the kernel has been configured with ``CONFIG_PAGE_POOL_STATS=y``. + * A pointer to a caller allocated struct page_pool_stats structure + * is passed to this API which is filled in. The caller can then report + * those stats to the user (perhaps via ethtool, debugfs, etc.). + */ bool page_pool_get_stats(struct page_pool *pool, struct page_pool_stats *stats) { @@ -224,6 +235,10 @@ static int page_pool_init(struct page_pool *pool, return 0; } +/** + * page_pool_create() - create a page pool. + * @params: parameters, see struct page_pool_params + */ struct page_pool *page_pool_create(const struct page_pool_params *params) { struct page_pool *pool; @@ -626,7 +641,21 @@ void page_pool_put_defragged_page(struct page_pool *pool, struct page *page, } EXPORT_SYMBOL(page_pool_put_defragged_page); -/* Caller must not use data area after call, as this function overwrites it */ +/** + * page_pool_put_page_bulk() - release references on multiple pages + * @pool: pool from which pages were allocated + * @data: array holding page pointers + * @count: number of pages in @data + * + * Tries to refill a number of pages into the ptr_ring cache holding ptr_ring + * producer lock. If the ptr_ring is full, page_pool_put_page_bulk() + * will release leftover pages to the page allocator. + * page_pool_put_page_bulk() is suitable to be run inside the driver NAPI tx + * completion loop for the XDP_REDIRECT use case. + * + * Please note the caller must not use data area after running + * page_pool_put_page_bulk(), as this function overwrites it. + */ void page_pool_put_page_bulk(struct page_pool *pool, void **data, int count) { |