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Diffstat (limited to 'include/net/page_pool.h')
| -rw-r--r-- | include/net/page_pool.h | 144 |
1 files changed, 144 insertions, 0 deletions
diff --git a/include/net/page_pool.h b/include/net/page_pool.h new file mode 100644 index 000000000..694d055e0 --- /dev/null +++ b/include/net/page_pool.h @@ -0,0 +1,144 @@ +/* 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(). + * + * If page_pool handles DMA mapping (use page->private), then API user + * is responsible for invoking page_pool_put_page() once. In-case of + * elevated refcnt, the DMA state is released, assuming other users of + * the page will eventually call put_page(). + * + * If no DMA mapping is done, then it can act as shim-layer that + * fall-through to alloc_page. As no state is kept on the page, the + * regular put_page() call is sufficient. + */ +#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 1 /* Should page_pool do the DMA map/unmap */ +#define PP_FLAG_ALL PP_FLAG_DMA_MAP + +/* + * 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; + void *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 */ +}; + +struct page_pool { + struct rcu_head rcu; + struct page_pool_params p; + + /* + * 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; +}; + +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_pool *page_pool_create(const struct page_pool_params *params); + +void page_pool_destroy(struct page_pool *pool); + +/* Never call this directly, use helpers below */ +void __page_pool_put_page(struct page_pool *pool, + struct page *page, bool allow_direct); + +static inline void page_pool_put_page(struct page_pool *pool, + struct page *page, 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 + __page_pool_put_page(pool, page, allow_direct); +#endif +} +/* Very limited use-cases allow recycle direct */ +static inline void page_pool_recycle_direct(struct page_pool *pool, + struct page *page) +{ + __page_pool_put_page(pool, page, true); +} + +static inline bool is_page_pool_compiled_in(void) +{ +#ifdef CONFIG_PAGE_POOL + return true; +#else + return false; +#endif +} + +#endif /* _NET_PAGE_POOL_H */ |