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authorSantiago Leon <santil@linux.vnet.ibm.com>2010-09-03 18:28:20 +0000
committerDavid S. Miller <davem@davemloft.net>2010-09-06 18:20:33 -0700
commitc08cc3ccebd46dce44d13a8ce81d249e687eeb8a (patch)
tree1e44318be42fbbef6c6cc224c9d4a2adafef4e98 /drivers/net/ibmveth.c
parente8cb7eb473ac47703282db6f90b4926f31cdf376 (diff)
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: Anton Blanchard <anton@samba.org> Signed-off-by: Santiago Leon <santil@linux.vnet.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/net/ibmveth.c')
-rw-r--r--drivers/net/ibmveth.c28
1 files changed, 20 insertions, 8 deletions
diff --git a/drivers/net/ibmveth.c b/drivers/net/ibmveth.c
index 9d662dec21b0..fc6e2cf879c0 100644
--- a/drivers/net/ibmveth.c
+++ b/drivers/net/ibmveth.c
@@ -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;
}
- 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");
+ 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");
+ 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;