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From: Ilias Apalodimas <ilias.apalodimas@linaro.org>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: davem@davemloft.net, kuba@kernel.org, hawk@kernel.org,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
	hkallweit1@gmail.com
Subject: Re: [PATCH net-next v2 2/2] page_pool: optimize the cpu sync operation when DMA mapping
Date: Fri, 20 Aug 2021 12:39:45 +0300	[thread overview]
Message-ID: <YR94YYRv2qpQtdSZ@Iliass-MBP> (raw)
In-Reply-To: <1629442611-61547-3-git-send-email-linyunsheng@huawei.com>

On Fri, Aug 20, 2021 at 02:56:51PM +0800, 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 cpu sync function again.

Isn't DMA_ATTR_SKIP_CPU_SYNC checked within dma_map_page_attrs() anyway?

Regards
/Ilias
> 
> 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
> 

  reply	other threads:[~2021-08-20  9:39 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-20  6:56 [PATCH net-next v2 0/2] Some minor optimization for page pool Yunsheng Lin
2021-08-20  6:56 ` [PATCH net-next v2 1/2] page_pool: use relaxed atomic for release side accounting Yunsheng Lin
2021-08-20  7:12   ` Jesper Dangaard Brouer
2021-08-20  6:56 ` [PATCH net-next v2 2/2] page_pool: optimize the cpu sync operation when DMA mapping Yunsheng Lin
2021-08-20  9:39   ` Ilias Apalodimas [this message]
2021-08-23  3:56     ` Yunsheng Lin
2021-08-23 12:42       ` Ilias Apalodimas
2021-08-24  7:00         ` Yunsheng Lin
2021-08-24  9:04           ` Ilias Apalodimas

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