ibmveth: Add rx_copybreak

For small packets, create a new skb and copy the packet into it so we
avoid tearing down and creating a TCE entry.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Santiago Leon <santil@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 23 insertions, 6 deletions

diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
index fc6e2cf879c0..c236c8af3367 100644
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -122,6 +122,11 @@ module_param(tx_copybreak, uint, 0644);
 MODULE_PARM_DESC(tx_copybreak,
         "Maximum size of packet that is copied to a new buffer on transmit");
 
+static unsigned int rx_copybreak __read_mostly = 128;
+module_param(rx_copybreak, uint, 0644);
+MODULE_PARM_DESC(rx_copybreak,
+        "Maximum size of packet that is copied to a new buffer on receive");
+
 struct ibmveth_stat {
         char name[ETH_GSTRING_LEN];
         int offset;
@@ -1002,8 +1007,6 @@ static int ibmveth_poll(struct napi_struct *napi, int budget)
 
  restart_poll:
         do {
-                struct sk_buff *skb;
-
                 if (!ibmveth_rxq_pending_buffer(adapter))
                         break;
 
@@ -1014,20 +1017,34 @@ static int ibmveth_poll(struct napi_struct *napi, int budget)
                         ibmveth_debug_printk("recycling invalid buffer\n");
                         ibmveth_rxq_recycle_buffer(adapter);
                 } else {
+                        struct sk_buff *skb, *new_skb;
                         int length = ibmveth_rxq_frame_length(adapter);
                         int offset = ibmveth_rxq_frame_offset(adapter);
                         int csum_good = ibmveth_rxq_csum_good(adapter);
 
                         skb = ibmveth_rxq_get_buffer(adapter);
-                        if (csum_good)
-                                skb->ip_summed = CHECKSUM_UNNECESSARY;
 
-                        ibmveth_rxq_harvest_buffer(adapter);
+                        new_skb = NULL;
+                        if (length < rx_copybreak)
+                                new_skb = netdev_alloc_skb(netdev, length);
+
+                        if (new_skb) {
+                                skb_copy_to_linear_data(new_skb,
+                                                        skb->data + offset,
+                                                        length);
+                                skb = new_skb;
+                                ibmveth_rxq_recycle_buffer(adapter);
+                        } else {
+                                ibmveth_rxq_harvest_buffer(adapter);
+                                skb_reserve(skb, offset);
+                        }
 
-                        skb_reserve(skb, offset);
                         skb_put(skb, length);
                         skb->protocol = eth_type_trans(skb, netdev);
 
+                        if (csum_good)
+                                skb->ip_summed = CHECKSUM_UNNECESSARY;
+
                         netif_receive_skb(skb); /* send it up */
 
                         netdev->stats.rx_packets++;