linux/include/net/page_pool.h
Yunsheng Lin 53e0961da1 page_pool: add frag page recycling support in page pool
Currently page pool only support page recycling when there
is only one user of the page, and the split page reusing
implemented in the most driver can not use the page pool as
bing-pong way of reusing requires the multi user support in
page pool.

Those reusing or recycling has below limitations:
1. page from page pool can only be used be one user in order
   for the page recycling to happen.
2. Bing-pong way of reusing in most driver does not support
   multi desc using different part of the same page in order
   to save memory.

So add multi-users support and frag page recycling in page
pool to overcome the above limitation.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2021-08-09 15:49:00 -07:00

304 lines
8.9 KiB
C

/* 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 */
};
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;
/*
* 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;
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);
#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 *));
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 *))
{
}
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_page(struct page_pool *pool, struct page *page,
unsigned int dma_sync_size, bool allow_direct);
/* 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)
{
/* 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, -1, allow_direct);
#endif
}
/* 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 void page_pool_set_frag_count(struct page *page, long nr)
{
atomic_long_set(&page->pp_frag_count, nr);
}
static inline long page_pool_atomic_sub_frag_count_return(struct page *page,
long nr)
{
long ret;
/* As suggested by Alexander, atomic_long_read() may cover up the
* reference count errors, so avoid calling atomic_long_read() in
* the cases of freeing or draining the page_frags, where we would
* not expect it to match or that are slowpath anyway.
*/
if (__builtin_constant_p(nr) &&
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 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);
}
static inline void page_pool_ring_lock(struct page_pool *pool)
__acquires(&pool->ring.producer_lock)
{
if (in_serving_softirq())
spin_lock(&pool->ring.producer_lock);
else
spin_lock_bh(&pool->ring.producer_lock);
}
static inline void page_pool_ring_unlock(struct page_pool *pool)
__releases(&pool->ring.producer_lock)
{
if (in_serving_softirq())
spin_unlock(&pool->ring.producer_lock);
else
spin_unlock_bh(&pool->ring.producer_lock);
}
#endif /* _NET_PAGE_POOL_H */