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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: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Alexander Duyck 2017-01-17 08:37:13 -08:00 committed by Jeff Kirsher
parent 2ccdf26ff6
commit 6f429223b3
1 changed files with 48 additions and 1 deletions
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49
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
View File

@ -1896,7 +1896,7 @@ static bool ixgbe_cleanup_headers(struct ixgbe_ring *rx_ring,
}
/* place header in linear portion of buffer */
if (skb_is_nonlinear(skb))
if (!skb_headlen(skb))
ixgbe_pull_tail(rx_ring, skb);
#ifdef IXGBE_FCOE
@ -2125,6 +2125,49 @@ static struct sk_buff *ixgbe_construct_skb(struct ixgbe_ring *rx_ring,
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
* @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 */
if (skb)
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
skb = ixgbe_construct_skb(rx_ring, rx_buffer,
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))
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)
continue;