Messages in this thread | | | Subject | Re: [PATCH net-next 2/2] page_pool: optimize the cpu sync operation when DMA mapping | From | Yunsheng Lin <> | Date | Fri, 20 Aug 2021 14:29:46 +0800 |
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On 2021/8/20 14:10, Heiner Kallweit wrote: > On 20.08.2021 04:06, Yunsheng Lin wrote: >> 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. >> > This shouldn't be needed. dma_mapping_error() will be (most likely) > inlined by the compiler, and it includes the unlikely() hint.
Good point, will remove the unlikely() mark. Thanks.
> >> Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com> >> --- >> 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; >> } >> >> > > . >
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