Commit c08cc3cc authored by Santiago Leon's avatar Santiago Leon Committed by David S. Miller
Browse files

ibmveth: Add tx_copybreak 



Use the existing bounce buffer if we send a buffer under a certain size.
This saves the overhead of a TCE map/unmap.

I can't see any reason for the wmb() in the bounce buffer case, if we need
a barrier it will be before we call h_send_logical_lan but we have
nothing in the common case. Remove it.

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarSantiago Leon <santil@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e8cb7eb4

drivers/net/ibmveth.c

+20 −8
Original line number Diff line number Diff line
@@ -117,6 +117,11 @@ MODULE_DESCRIPTION("IBM i/pSeries Virtual Ethernet Driver"); 
MODULE_LICENSE("GPL");

MODULE_VERSION(ibmveth_driver_version);



static unsigned int tx_copybreak __read_mostly = 128;

module_param(tx_copybreak, uint, 0644);

MODULE_PARM_DESC(tx_copybreak,

	"Maximum size of packet that is copied to a new buffer on transmit");



struct ibmveth_stat {

	char name[ETH_GSTRING_LEN];

	int offset;
@@ -931,17 +936,24 @@ static netdev_tx_t ibmveth_start_xmit(struct sk_buff *skb, 
		buf[1] = 0;

	}



	if (skb->len < tx_copybreak) {

		used_bounce = 1;

	} else {

		data_dma_addr = dma_map_single(&adapter->vdev->dev, skb->data,

					       skb->len, DMA_TO_DEVICE);

		if (dma_mapping_error(&adapter->vdev->dev, data_dma_addr)) {

			if (!firmware_has_feature(FW_FEATURE_CMO))

			ibmveth_error_printk("tx: unable to map xmit buffer\n");

				ibmveth_error_printk("tx: unable to map "

						     "xmit buffer\n");

			tx_map_failed++;

			used_bounce = 1;

		}

	}



	if (used_bounce) {

		skb_copy_from_linear_data(skb, adapter->bounce_buffer,

					  skb->len);

		desc.fields.address = adapter->bounce_buffer_dma;

		tx_map_failed++;

		used_bounce = 1;

		wmb();

	} else

		desc.fields.address = data_dma_addr;

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