i40e/i40evf: improve Tx performance with a small tweak

Orabug: 21570582

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>
(cherry picked from commit 489ce7a46306052ab4ef26c6305051c5f1b24bb4)
Signed-off-by: Brian Maly <brian.maly@oracle.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>

diff --git a/drivers/net/ethernet/intel/i40e/i40e_txrx.c b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
index a8a8232e363ec91435e15214d402fa490ea6bb57..7e018fbf5ff8359001685b39521289b2b61b33eb 100644 (file)
--- a/drivers/net/ethernet/intel/i40e/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_txrx.c
@@ -2618,6 +2618,8 @@ 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 690e67ee9fbffcfc4ac6c5a4ceefb28e5ca7f146..35a647fa6ffba72d10ed76c03645911a0ad4234b 100644 (file)
--- a/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
+++ b/drivers/net/ethernet/intel/i40evf/i40e_txrx.c
@@ -1843,6 +1843,8 @@ 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;