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Commit 6f429223 authored by Alexander Duyck's avatar Alexander Duyck Committed by Jeff Kirsher
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ixgbe: Add support for build_skb 



This patch adds build_skb support to the Rx path.  There are several
advantages to this change.

1.  It avoids the memcpy and skb->head allocation for small packets which
    improves performance by about 5% in my tests.
2.  It avoids the memcpy, skb->head allocation, and eth_get_headlen
    for larger packets improving performance by about 10% in my tests.
3.  For VXLAN packets it allows the full header to be in skb->data which
    improves the performance by as much as 30% in some of my tests.

Signed-off-by: default avatarAlexander Duyck <alexander.h.duyck@intel.com>
Tested-by: default avatarAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 2ccdf26f

drivers/net/ethernet/intel/ixgbe/ixgbe_main.c

+48 −1
Original line number Original line Diff line number Diff line
@@ -1896,7 +1896,7 @@ static bool ixgbe_cleanup_headers(struct ixgbe_ring *rx_ring, 
	}

	}





	/* place header in linear portion of buffer */

	/* place header in linear portion of buffer */

	if (skb_is_nonlinear(skb))

	if (!skb_headlen(skb))

		ixgbe_pull_tail(rx_ring, skb);

		ixgbe_pull_tail(rx_ring, skb);





#ifdef IXGBE_FCOE

#ifdef IXGBE_FCOE
@@ -2125,6 +2125,49 @@ static struct sk_buff *ixgbe_construct_skb(struct ixgbe_ring *rx_ring, 
	return skb;

	return skb;

}

}





static struct sk_buff *ixgbe_build_skb(struct ixgbe_ring *rx_ring,

				       struct ixgbe_rx_buffer *rx_buffer,

				       union ixgbe_adv_rx_desc *rx_desc,

				       unsigned int size)

{

	void *va = page_address(rx_buffer->page) + rx_buffer->page_offset;

#if (PAGE_SIZE < 8192)

	unsigned int truesize = ixgbe_rx_pg_size(rx_ring) / 2;

#else

	unsigned int truesize = SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) +

				SKB_DATA_ALIGN(IXGBE_SKB_PAD + size);

#endif

	struct sk_buff *skb;



	/* prefetch first cache line of first page */

	prefetch(va);

#if L1_CACHE_BYTES < 128

	prefetch(va + L1_CACHE_BYTES);

#endif



	/* build an skb to around the page buffer */

	skb = build_skb(va - IXGBE_SKB_PAD, truesize);

	if (unlikely(!skb))

		return NULL;



	/* update pointers within the skb to store the data */

	skb_reserve(skb, IXGBE_SKB_PAD);

	__skb_put(skb, size);



	/* record DMA address if this is the start of a chain of buffers */

	if (!ixgbe_test_staterr(rx_desc, IXGBE_RXD_STAT_EOP))

		IXGBE_CB(skb)->dma = rx_buffer->dma;



	/* update buffer offset */

#if (PAGE_SIZE < 8192)

	rx_buffer->page_offset ^= truesize;

#else

	rx_buffer->page_offset += truesize;

#endif



	return skb;

}



/**

/**

 * ixgbe_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf

 * ixgbe_clean_rx_irq - Clean completed descriptors from Rx ring - bounce buf

 * @q_vector: structure containing interrupt and ring information

 * @q_vector: structure containing interrupt and ring information
@@ -2178,6 +2221,9 @@ static int ixgbe_clean_rx_irq(struct ixgbe_q_vector *q_vector, 
		/* retrieve a buffer from the ring */

		/* retrieve a buffer from the ring */

		if (skb)

		if (skb)

			ixgbe_add_rx_frag(rx_ring, rx_buffer, skb, size);

			ixgbe_add_rx_frag(rx_ring, rx_buffer, skb, size);

		else if (ring_uses_build_skb(rx_ring))

			skb = ixgbe_build_skb(rx_ring, rx_buffer,

					      rx_desc, size);

		else

		else

			skb = ixgbe_construct_skb(rx_ring, rx_buffer,

			skb = ixgbe_construct_skb(rx_ring, rx_buffer,

						  rx_desc, size);

						  rx_desc, size);
@@ -3918,6 +3964,7 @@ static void ixgbe_set_rx_buffer_len(struct ixgbe_adapter *adapter) 
		if (test_bit(__IXGBE_RX_FCOE, &rx_ring->state))

		if (test_bit(__IXGBE_RX_FCOE, &rx_ring->state))

			set_bit(__IXGBE_RX_3K_BUFFER, &rx_ring->state);

			set_bit(__IXGBE_RX_3K_BUFFER, &rx_ring->state);





		clear_bit(__IXGBE_RX_BUILD_SKB_ENABLED, &rx_ring->state);

		if (adapter->flags2 & IXGBE_FLAG2_RX_LEGACY)

		if (adapter->flags2 & IXGBE_FLAG2_RX_LEGACY)

			continue;

			continue;