i40e/i40evf: improve Tx performance with a small tweak

Add a prefetch for the next Tx descriptor to be used when we know
there are more coming.

Change-ID: Ibb9acab11d508eec2db7da795df74debc16eeacb
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index 9a4f2bc..1fe230d 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2616,6 +2616,8 @@ static inline void i40e_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
            netif_xmit_stopped(netdev_get_tx_queue(tx_ring->netdev,
                                                   tx_ring->queue_index)))
                writel(i, tx_ring->tail);
+       else
+               prefetchw(tx_desc + 1);
 
        return;
 

diff --git a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
index 395f32f..0f0e185 100644 (file)
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -1841,6 +1841,8 @@ static inline void i40evf_tx_map(struct i40e_ring *tx_ring, struct sk_buff *skb,
            netif_xmit_stopped(netdev_get_tx_queue(tx_ring->netdev,
                                                   tx_ring->queue_index)))
                writel(i, tx_ring->tail);
+       else
+               prefetchw(tx_desc + 1);
 
        return;