On some platforms, syncing a buffer for DMA is expensive. Rather than
sync the whole 2K receive buffer, only synchronise the length of the
frame, which will typically be the MTU, or a much smaller TCP ACK.
For an IMX6Q, this gives around 6% increased TCP receive performance,
which is cache operations bound and reduces CPU load for TCP transmit.
Signed-off-by: Andrew Lunn <and...@lunn.ch>
---
drivers/net/ethernet/intel/igb/igb_main.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c
b/drivers/net/ethernet/intel/igb/igb_main.c
index 0a289dda604a..670e3d612283 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -6915,6 +6915,7 @@ static struct sk_buff *igb_fetch_rx_buffer(struct
igb_ring *rx_ring,
{
struct igb_rx_buffer *rx_buffer;
struct page *page;
+ unsigned int 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;
@@ -6948,7 +6949,7 @@ static struct sk_buff *igb_fetch_rx_buffer(struct
igb_ring *rx_ring,
dma_sync_single_range_for_cpu(rx_ring->dev,
rx_buffer->dma,
rx_buffer->page_offset,
- IGB_RX_BUFSZ,
+ size,
DMA_FROM_DEVICE);
/* pull page into skb */
--
2.8.1
