[Intel-wired-lan] [PATCH 8/9] ixgbevf: break out Rx buffer page management

Singh, Krishneil K krishneil.k.singh at intel.com
Mon Feb 26 16:05:30 UTC 2018


> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces at osuosl.org] On Behalf Of
> Emil Tantilov
> Sent: Tuesday, January 30, 2018 4:52 PM
> To: intel-wired-lan at lists.osuosl.org
> Subject: [Intel-wired-lan] [PATCH 8/9] ixgbevf: break out Rx buffer page
> management
> 
> Based on commit e014272672b9 ("igb: Break out Rx buffer page management")
> 
> Consolidate Rx code paths to reduce duplication when we expand them in
> the future.
> 
> 
> Signed-off-by: Emil Tantilov <emil.s.tantilov at intel.com>
> ---
>  drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c |  227 +++++++++++----------
>  1 file changed, 114 insertions(+), 113 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> index 754efb4..cd8c0a0 100644
> --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c
> @@ -130,6 +130,9 @@ static void ixgbevf_service_event_complete(struct
> ixgbevf_adapter *adapter)
>  static void ixgbevf_queue_reset_subtask(struct ixgbevf_adapter *adapter);
>  static void ixgbevf_set_itr(struct ixgbevf_q_vector *q_vector);
>  static void ixgbevf_free_all_rx_resources(struct ixgbevf_adapter *adapter);
> +static bool ixgbevf_can_reuse_rx_page(struct ixgbevf_rx_buffer *rx_buffer);
> +static void ixgbevf_reuse_rx_page(struct ixgbevf_ring *rx_ring,
> +				  struct ixgbevf_rx_buffer *old_buff);
> 
>  static void ixgbevf_remove_adapter(struct ixgbe_hw *hw)
>  {
> @@ -527,6 +530,49 @@ static void ixgbevf_process_skb_fields(struct
> ixgbevf_ring *rx_ring,
>  	skb->protocol = eth_type_trans(skb, rx_ring->netdev);
>  }
> 
> +static
> +struct ixgbevf_rx_buffer *ixgbevf_get_rx_buffer(struct ixgbevf_ring *rx_ring,
> +						const unsigned int size)
> +{
> +	struct ixgbevf_rx_buffer *rx_buffer;
> +
> +	rx_buffer = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
> +	prefetchw(rx_buffer->page);
> +
> +	/* we are reusing so sync this buffer for CPU use */
> +	dma_sync_single_range_for_cpu(rx_ring->dev,
> +				      rx_buffer->dma,
> +				      rx_buffer->page_offset,
> +				      size,
> +				      DMA_FROM_DEVICE);
> +
> +	rx_buffer->pagecnt_bias--;
> +
> +	return rx_buffer;
> +}
> +
> +static void ixgbevf_put_rx_buffer(struct ixgbevf_ring *rx_ring,
> +				  struct ixgbevf_rx_buffer *rx_buffer)
> +{
> +	if (ixgbevf_can_reuse_rx_page(rx_buffer)) {
> +		/* hand second half of page back to the ring */
> +		ixgbevf_reuse_rx_page(rx_ring, rx_buffer);
> +	} else {
> +		/* We are not reusing the buffer so unmap it and free
> +		 * any references we are holding to it
> +		 */
> +		dma_unmap_page_attrs(rx_ring->dev, rx_buffer->dma,
> +				     ixgbevf_rx_pg_size(rx_ring),
> +				     DMA_FROM_DEVICE,
> +				     IXGBEVF_RX_DMA_ATTR);
> +		__page_frag_cache_drain(rx_buffer->page,
> +					rx_buffer->pagecnt_bias);
> +	}
> +
> +	/* clear contents of rx_buffer */
> +	rx_buffer->page = NULL;
> +}
> +
>  /**
>   * ixgbevf_is_non_eop - process handling of non-EOP buffers
>   * @rx_ring: Rx ring being processed
> @@ -740,11 +786,10 @@ static inline bool ixgbevf_page_is_reserved(struct
> page *page)
>  	return (page_to_nid(page) != numa_mem_id()) ||
> page_is_pfmemalloc(page);
>  }
> 
> -static bool ixgbevf_can_reuse_rx_page(struct ixgbevf_rx_buffer *rx_buffer,
> -				      struct page *page,
> -				      const unsigned int truesize)
> +static bool ixgbevf_can_reuse_rx_page(struct ixgbevf_rx_buffer *rx_buffer)
>  {
> -	unsigned int pagecnt_bias = rx_buffer->pagecnt_bias--;
> +	unsigned int pagecnt_bias = rx_buffer->pagecnt_bias;
> +	struct page *page = rx_buffer->page;
> 
>  	/* avoid re-using remote pages */
>  	if (unlikely(ixgbevf_page_is_reserved(page)))
> @@ -752,16 +797,9 @@ static bool ixgbevf_can_reuse_rx_page(struct
> ixgbevf_rx_buffer *rx_buffer,
> 
>  #if (PAGE_SIZE < 8192)
>  	/* if we are only owner of page we can reuse it */
> -	if (unlikely(page_ref_count(page) != pagecnt_bias))
> +	if (unlikely((page_ref_count(page) - pagecnt_bias) > 1))
>  		return false;
> -
> -	/* flip page offset to other buffer */
> -	rx_buffer->page_offset ^= truesize;
> -
>  #else
> -	/* move offset up to the next cache line */
> -	rx_buffer->page_offset += truesize;
> -
>  #define IXGBEVF_LAST_OFFSET \
>  	(SKB_WITH_OVERHEAD(PAGE_SIZE) - IXGBEVF_RXBUFFER_2048)
> 
> @@ -774,7 +812,7 @@ static bool ixgbevf_can_reuse_rx_page(struct
> ixgbevf_rx_buffer *rx_buffer,
>  	 * the pagecnt_bias and page count so that we fully restock the
>  	 * number of references the driver holds.
>  	 */
> -	if (unlikely(pagecnt_bias == 1)) {
> +	if (unlikely(!pagecnt_bias)) {
>  		page_ref_add(page, USHRT_MAX);
>  		rx_buffer->pagecnt_bias = USHRT_MAX;
>  	}
> @@ -786,25 +824,16 @@ static bool ixgbevf_can_reuse_rx_page(struct
> ixgbevf_rx_buffer *rx_buffer,
>   * ixgbevf_add_rx_frag - Add contents of Rx buffer to sk_buff
>   * @rx_ring: rx descriptor ring to transact packets on
>   * @rx_buffer: buffer containing page to add
> - * @rx_desc: descriptor containing length of buffer written by hardware
>   * @skb: sk_buff to place the data into
> + * @size: size of buffer to be added
>   *
>   * This function will add the data contained in rx_buffer->page to the skb.
> - * This is done either through a direct copy if the data in the buffer is
> - * less than the skb header size, otherwise it will just attach the page as
> - * a frag to the skb.
> - *
> - * The function will then update the page offset if necessary and return
> - * true if the buffer can be reused by the adapter.
>   **/
> -static bool ixgbevf_add_rx_frag(struct ixgbevf_ring *rx_ring,
> +static void ixgbevf_add_rx_frag(struct ixgbevf_ring *rx_ring,
>  				struct ixgbevf_rx_buffer *rx_buffer,
> -				u16 size,
> -				union ixgbe_adv_rx_desc *rx_desc,
> -				struct sk_buff *skb)
> +				struct sk_buff *skb,
> +				unsigned int size)
>  {
> -	struct page *page = rx_buffer->page;
> -	void *va = page_address(page) + rx_buffer->page_offset;
>  #if (PAGE_SIZE < 8192)
>  	unsigned int truesize = ixgbevf_rx_pg_size(rx_ring) / 2;
>  #else
> @@ -812,102 +841,64 @@ static bool ixgbevf_add_rx_frag(struct ixgbevf_ring
> *rx_ring,
>  				SKB_DATA_ALIGN(IXGBEVF_SKB_PAD + size) :
>  				SKB_DATA_ALIGN(size);
>  #endif
> -	unsigned int pull_len;
> -
> -	if (unlikely(skb_is_nonlinear(skb)))
> -		goto add_tail_frag;
> -
> -	if (likely(size <= IXGBEVF_RX_HDR_SIZE)) {
> -		memcpy(__skb_put(skb, size), va, ALIGN(size, sizeof(long)));
> -
> -		/* page is not reserved, we can reuse buffer as is */
> -		if (likely(!ixgbevf_page_is_reserved(page)))
> -			return true;
> -
> -		/* this page cannot be reused so discard it */
> -		return false;
> -	}
> -
> -	/* we need the header to contain the greater of either ETH_HLEN or
> -	 * 60 bytes if the skb->len is less than 60 for skb_pad.
> -	 */
> -	pull_len = eth_get_headlen(va, IXGBEVF_RX_HDR_SIZE);
> -
> -	/* align pull length to size of long to optimize memcpy performance */
> -	memcpy(__skb_put(skb, pull_len), va, ALIGN(pull_len, sizeof(long)));
> -
> -	/* update all of the pointers */
> -	va += pull_len;
> -	size -= pull_len;
> -
> -add_tail_frag:
> -	skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, page,
> -			va - page_address(page), size, truesize);
> -
> -	return ixgbevf_can_reuse_rx_page(rx_buffer, page, truesize);
> +	skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, rx_buffer->page,
> +			rx_buffer->page_offset, size, truesize);
> +#if (PAGE_SIZE < 8192)
> +	rx_buffer->page_offset ^= truesize;
> +#else
> +	rx_buffer->page_offset += truesize;
> +#endif
>  }
> 
> -static struct sk_buff *ixgbevf_fetch_rx_buffer(struct ixgbevf_ring *rx_ring,
> -					       union ixgbe_adv_rx_desc
> *rx_desc,
> -					       struct sk_buff *skb)
> +static
> +struct sk_buff *ixgbevf_construct_skb(struct ixgbevf_ring *rx_ring,
> +				      struct ixgbevf_rx_buffer *rx_buffer,
> +				      union ixgbe_adv_rx_desc *rx_desc,
> +				      unsigned int size)
>  {
> -	struct ixgbevf_rx_buffer *rx_buffer;
> -	struct page *page;
> -	u16 size = le16_to_cpu(rx_desc->wb.upper.length);
> -
> -	rx_buffer = &rx_ring->rx_buffer_info[rx_ring->next_to_clean];
> -	page = rx_buffer->page;
> -	prefetchw(page);
> -
> -	/* we are reusing so sync this buffer for CPU use */
> -	dma_sync_single_range_for_cpu(rx_ring->dev,
> -				      rx_buffer->dma,
> -				      rx_buffer->page_offset,
> -				      size,
> -				      DMA_FROM_DEVICE);
> -
> -	if (likely(!skb)) {
> -		void *va = page_address(page) + rx_buffer->page_offset;
> +	void *va = page_address(rx_buffer->page) + rx_buffer->page_offset;
> +#if (PAGE_SIZE < 8192)
> +	unsigned int truesize = ixgbevf_rx_pg_size(rx_ring) / 2;
> +#else
> +	unsigned int truesize = SKB_DATA_ALIGN(size);
> +#endif
> +	unsigned int headlen;
> +	struct sk_buff *skb;
> 
> -		/* prefetch first cache line of first page */
> -		prefetch(va);
> +	/* prefetch first cache line of first page */
> +	prefetch(va);
>  #if L1_CACHE_BYTES < 128
> -		prefetch(va + L1_CACHE_BYTES);
> +	prefetch(va + L1_CACHE_BYTES);
>  #endif
> 
> -		/* allocate a skb to store the frags */
> -		skb = netdev_alloc_skb_ip_align(rx_ring->netdev,
> -						IXGBEVF_RX_HDR_SIZE);
> -		if (unlikely(!skb)) {
> -			rx_ring->rx_stats.alloc_rx_buff_failed++;
> -			return NULL;
> -		}
> +	/* allocate a skb to store the frags */
> +	skb = napi_alloc_skb(&rx_ring->q_vector->napi,
> IXGBEVF_RX_HDR_SIZE);
> +	if (unlikely(!skb))
> +		return NULL;
> 
> -		/* we will be copying header into skb->data in
> -		 * pskb_may_pull so it is in our interest to prefetch
> -		 * it now to avoid a possible cache miss
> -		 */
> -		prefetchw(skb->data);
> -	}
> +	/* Determine available headroom for copy */
> +	headlen = size;
> +	if (headlen > IXGBEVF_RX_HDR_SIZE)
> +		headlen = eth_get_headlen(va, IXGBEVF_RX_HDR_SIZE);
> 
> -	/* pull page into skb */
> -	if (ixgbevf_add_rx_frag(rx_ring, rx_buffer, size, rx_desc, skb)) {
> -		/* hand second half of page back to the ring */
> -		ixgbevf_reuse_rx_page(rx_ring, rx_buffer);
> +	/* align pull length to size of long to optimize memcpy performance */
> +	memcpy(__skb_put(skb, headlen), va, ALIGN(headlen, sizeof(long)));
> +
> +	/* update all of the pointers */
> +	size -= headlen;
> +	if (size) {
> +		skb_add_rx_frag(skb, 0, rx_buffer->page,
> +				(va + headlen) - page_address(rx_buffer-
> >page),
> +				size, truesize);
> +#if (PAGE_SIZE < 8192)
> +		rx_buffer->page_offset ^= truesize;
> +#else
> +		rx_buffer->page_offset += truesize;
> +#endif
>  	} else {
> -		/* We are not reusing the buffer so unmap it and free
> -		 * any references we are holding to it
> -		 */
> -		dma_unmap_page_attrs(rx_ring->dev, rx_buffer->dma,
> -				     ixgbevf_rx_pg_size(rx_ring),
> -				     DMA_FROM_DEVICE,
> IXGBEVF_RX_DMA_ATTR);
> -		__page_frag_cache_drain(page, rx_buffer->pagecnt_bias);
> +		rx_buffer->pagecnt_bias++;
>  	}
> 
> -	/* clear contents of buffer_info */
> -	rx_buffer->dma = 0;
> -	rx_buffer->page = NULL;
> -
>  	return skb;
>  }
> 
> @@ -929,6 +920,8 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector
> *q_vector,
> 
>  	while (likely(total_rx_packets < budget)) {
>  		union ixgbe_adv_rx_desc *rx_desc;
> +		struct ixgbevf_rx_buffer *rx_buffer;
> +		unsigned int size;
> 
>  		/* return some buffers to hardware, one at a time is too slow */
>  		if (cleaned_count >= IXGBEVF_RX_BUFFER_WRITE) {
> @@ -937,8 +930,8 @@ static int ixgbevf_clean_rx_irq(struct ixgbevf_q_vector
> *q_vector,
>  		}
> 
>  		rx_desc = IXGBEVF_RX_DESC(rx_ring, rx_ring->next_to_clean);
> -
> -		if (!rx_desc->wb.upper.length)
> +		size = le16_to_cpu(rx_desc->wb.upper.length);
> +		if (!size)
>  			break;
> 
>  		/* This memory barrier is needed to keep us from reading
> @@ -947,15 +940,23 @@ static int ixgbevf_clean_rx_irq(struct
> ixgbevf_q_vector *q_vector,
>  		 */
>  		rmb();
> 
> +		rx_buffer = ixgbevf_get_rx_buffer(rx_ring, size);
> +
>  		/* retrieve a buffer from the ring */
> -		skb = ixgbevf_fetch_rx_buffer(rx_ring, rx_desc, skb);
> +		if (skb)
> +			ixgbevf_add_rx_frag(rx_ring, rx_buffer, skb, size);
> +		else
> +			skb = ixgbevf_construct_skb(rx_ring, rx_buffer,
> +						    rx_desc, size);
> 
>  		/* exit if we failed to retrieve a buffer */
>  		if (!skb) {
>  			rx_ring->rx_stats.alloc_rx_buff_failed++;
> +			rx_buffer->pagecnt_bias++;
>  			break;
>  		}
> 
> +		ixgbevf_put_rx_buffer(rx_ring, rx_buffer);
>  		cleaned_count++;
> 
>  		/* fetch next buffer in frame if non-eop */
> 
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Tested-by: Krishneil Singh <krishneil.k.singh at intel.com>



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