[PATCH net-next 2/2] page_pool: optimize the cpu sync operation when DMA mapping
From: Yunsheng Lin <hidden>
Date: 2021-08-20 02:07:51
Also in:
lkml
Subsystem:
networking [general], page pool, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Jesper Dangaard Brouer, Ilias Apalodimas, Linus Torvalds
If the DMA_ATTR_SKIP_CPU_SYNC is not set, cpu syncing is also done in dma_map_page_attrs(), so set the attrs according to pool->p.flags to avoid calling dma sync function again. Also mark the dma error as the unlikely case While we are at it. Signed-off-by: Yunsheng Lin <redacted> --- net/core/page_pool.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1a69784..8172045 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c@@ -191,8 +191,12 @@ static void page_pool_dma_sync_for_device(struct page_pool *pool, static bool page_pool_dma_map(struct page_pool *pool, struct page *page) { + unsigned long attrs = DMA_ATTR_SKIP_CPU_SYNC; dma_addr_t dma; + if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) + attrs = 0; + /* Setup DMA mapping: use 'struct page' area for storing DMA-addr * since dma_addr_t can be either 32 or 64 bits and does not always fit * into page private data (i.e 32bit cpu with 64bit DMA caps)
@@ -200,15 +204,12 @@ static bool page_pool_dma_map(struct page_pool *pool, struct page *page) */ dma = dma_map_page_attrs(pool->p.dev, page, 0, (PAGE_SIZE << pool->p.order), - pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); - if (dma_mapping_error(pool->p.dev, dma)) + pool->p.dma_dir, attrs); + if (unlikely(dma_mapping_error(pool->p.dev, dma))) return false; page_pool_set_dma_addr(page, dma); - if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) - page_pool_dma_sync_for_device(pool, page, pool->p.max_len); - return true; }
--
2.7.4