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authorIlias Apalodimas <ilias.apalodimas@linaro.org>2021-06-07 21:02:38 +0200
committerDavid S. Miller <davem@davemloft.net>2021-06-07 14:11:47 -0700
commit6a5bcd84e886a9a91982e515c539529c28acdcc2 (patch)
tree4c47da6a3d932ef3bba0d56e121637d5461975ad /include/net/page_pool.h
parentc420c98982fa9e749c99e022845d5f323d098b72 (diff)
page_pool: Allow drivers to hint on SKB recycling
Up to now several high speed NICs have custom mechanisms of recycling the allocated memory they use for their payloads. Our page_pool API already has recycling capabilities that are always used when we are running in 'XDP mode'. So let's tweak the API and the kernel network stack slightly and allow the recycling to happen even during the standard operation. The API doesn't take into account 'split page' policies used by those drivers currently, but can be extended once we have users for that. The idea is to be able to intercept the packet on skb_release_data(). If it's a buffer coming from our page_pool API recycle it back to the pool for further usage or just release the packet entirely. To achieve that we introduce a bit in struct sk_buff (pp_recycle:1) and a field in struct page (page->pp) to store the page_pool pointer. Storing the information in page->pp allows us to recycle both SKBs and their fragments. We could have skipped the skb bit entirely, since identical information can bederived from struct page. However, in an effort to affect the free path as less as possible, reading a single bit in the skb which is already in cache, is better that trying to derive identical information for the page stored data. The driver or page_pool has to take care of the sync operations on it's own during the buffer recycling since the buffer is, after opting-in to the recycling, never unmapped. Since the gain on the drivers depends on the architecture, we are not enabling recycling by default if the page_pool API is used on a driver. In order to enable recycling the driver must call skb_mark_for_recycle() to store the information we need for recycling in page->pp and enabling the recycling bit, or page_pool_store_mem_info() for a fragment. Co-developed-by: Jesper Dangaard Brouer <brouer@redhat.com> Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com> Co-developed-by: Matteo Croce <mcroce@microsoft.com> Signed-off-by: Matteo Croce <mcroce@microsoft.com> Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include/net/page_pool.h')
-rw-r--r--include/net/page_pool.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/net/page_pool.h b/include/net/page_pool.h
index b4b6de909c93..3dd62dd73027 100644
--- a/include/net/page_pool.h
+++ b/include/net/page_pool.h
@@ -146,6 +146,8 @@ 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
@@ -251,4 +253,11 @@ static inline void page_pool_ring_unlock(struct page_pool *pool)
spin_unlock_bh(&pool->ring.producer_lock);
}
+/* Store mem_info on struct page and use it while recycling skb frags */
+static inline
+void page_pool_store_mem_info(struct page *page, struct page_pool *pp)
+{
+ page->pp = pp;
+}
+
#endif /* _NET_PAGE_POOL_H */