Commit 707f908e authored by Maxim Mikityanskiy's avatar Maxim Mikityanskiy Committed by Jakub Kicinski
Browse files

net/mlx5e: Optimize the page cache reducing its size 2x 



RX page cache stores dma_info structs, that consist of a pointer to
struct page and a DMA address. In fact, the DMA address is extracted
from struct page using page_pool_get_dma_addr when a page is pushed to
the cache. By moving this call to the point when a page is popped from
the cache, we can avoid storing the DMA address in the cache,
effectively reducing its size by two times without losing any
functionality.

Signed-off-by: default avatarMaxim Mikityanskiy <maximmi@nvidia.com>
Reviewed-by: default avatarSaeed Mahameed <saeedm@nvidia.com>
Reviewed-by: default avatarTariq Toukan <tariqt@nvidia.com>
Signed-off-by: default avatarSaeed Mahameed <saeedm@nvidia.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 0b9c86c7

drivers/net/ethernet/mellanox/mlx5/core/en.h

+1 −1
Original line number Diff line number Diff line
@@ -630,7 +630,7 @@ struct mlx5e_mpw_info { 
struct mlx5e_page_cache {

	u32 head;

	u32 tail;

	struct mlx5e_dma_info page_cache[MLX5E_CACHE_SIZE];

	struct page *page_cache[MLX5E_CACHE_SIZE];

};



struct mlx5e_rq;

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

+1 −3
Original line number Diff line number Diff line
@@ -830,13 +830,11 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq) 


	for (i = rq->page_cache.head; i != rq->page_cache.tail;

	     i = (i + 1) & (MLX5E_CACHE_SIZE - 1)) {

		struct mlx5e_dma_info *dma_info = &rq->page_cache.page_cache[i];



		/* With AF_XDP, page_cache is not used, so this loop is not

		 * entered, and it's safe to call mlx5e_page_release_dynamic

		 * directly.

		 */

		mlx5e_page_release_dynamic(rq, dma_info->page, false);

		mlx5e_page_release_dynamic(rq, rq->page_cache.page_cache[i], false);

	}



	xdp_rxq_info_unreg(&rq->xdp_rxq);

drivers/net/ethernet/mellanox/mlx5/core/en_rx.c

+4 −4
Original line number Diff line number Diff line
@@ -245,8 +245,7 @@ static inline bool mlx5e_rx_cache_put(struct mlx5e_rq *rq, struct page *page) 
		return false;

	}



	cache->page_cache[cache->tail].page = page;

	cache->page_cache[cache->tail].addr = page_pool_get_dma_addr(page);

	cache->page_cache[cache->tail] = page;

	cache->tail = tail_next;

	return true;

}
@@ -262,12 +261,13 @@ static inline bool mlx5e_rx_cache_get(struct mlx5e_rq *rq, 
		return false;

	}



	if (page_ref_count(cache->page_cache[cache->head].page) != 1) {

	if (page_ref_count(cache->page_cache[cache->head]) != 1) {

		stats->cache_busy++;

		return false;

	}



	*dma_info = cache->page_cache[cache->head];

	dma_info->page = cache->page_cache[cache->head];

	dma_info->addr = page_pool_get_dma_addr(dma_info->page);

	cache->head = (cache->head + 1) & (MLX5E_CACHE_SIZE - 1);

	stats->cache_reuse++;