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Subject[PATCH net-next v2 2/2] page_pool: optimize the cpu sync operation when DMA mapping
Date
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 cpu sync function again.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
net/core/page_pool.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 1a69784..3df5554 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);
+ pool->p.dma_dir, attrs);
if (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
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