net: e1000e: support txtd update delay via xmit_more

Don't update Tx tail descriptor if queue hasn't been stopped
and we know at least one more skb will be sent right away.

Signed-off-by: Florian Westphal <fw@strlen.de>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c b/drivers/net/ethernet/intel/e1000e/netdev.c
index aa39a81a6df6dc5fafaab03122b07333c6ecd701..1e8c40fd5c3d8fbc582dc19c4f71766023901968 100644 (file)
--- a/drivers/net/ethernet/intel/e1000e/netdev.c
+++ b/drivers/net/ethernet/intel/e1000e/netdev.c
@@ -5444,16 +5444,6 @@ static void e1000_tx_queue(struct e1000_ring *tx_ring, int tx_flags, int count)
        wmb();
 
        tx_ring->next_to_use = i;
-
-       if (adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
-               e1000e_update_tdt_wa(tx_ring, i);
-       else
-               writel(i, tx_ring->tail);
-
-       /* we need this if more than one processor can write to our tail
-        * at a time, it synchronizes IO on IA64/Altix systems
-        */
-       mmiowb();
 }
 
 #define MINIMUM_DHCP_PACKET_SIZE 282
@@ -5655,6 +5645,21 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
                                    (MAX_SKB_FRAGS *
                                     DIV_ROUND_UP(PAGE_SIZE,
                                                  adapter->tx_fifo_limit) + 2));
+
+               if (!skb->xmit_more ||
+                   netif_xmit_stopped(netdev_get_tx_queue(netdev, 0))) {
+                       if (adapter->flags2 & FLAG2_PCIM2PCI_ARBITER_WA)
+                               e1000e_update_tdt_wa(tx_ring,
+                                                    tx_ring->next_to_use);
+                       else
+                               writel(tx_ring->next_to_use, tx_ring->tail);
+
+                       /* we need this if more than one processor can write
+                        * to our tail at a time, it synchronizes IO on
+                        *IA64/Altix systems
+                        */
+                       mmiowb();
+               }
        } else {
                dev_kfree_skb_any(skb);
                tx_ring->buffer_info[first].time_stamp = 0;