On Wed, 2011-03-09 at 09:15 +0200, Michael S. Tsirkin wrote:
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 82dba5a..ebe3337 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -514,11 +514,11 @@ static unsigned int free_old_xmit_skbs(struct
> virtnet_info *vi)
> struct sk_buff *skb;
> unsigned int len, tot_sgs = 0;
>
> - while ((skb = virtqueue_get_buf(vi->svq, &len)) != NULL) {
> + if ((skb = virtqueue_get_buf(vi->svq, &len)) != NULL) {
> pr_debug("Sent skb %p\n", skb);
> vi->dev->stats.tx_bytes += skb->len;
> vi->dev->stats.tx_packets++;
> - tot_sgs += skb_vnet_hdr(skb)->num_sg;
> + tot_sgs = 2+MAX_SKB_FRAGS;
> dev_kfree_skb_any(skb);
> }
> return tot_sgs;
Return value should be different based on indirect or direct buffers
here?
> @@ -576,9 +576,6 @@ static netdev_tx_t start_xmit(struct sk_buff *skb,
> struct net_device *dev)
> struct virtnet_info *vi = netdev_priv(dev);
> int capacity;
>
> - /* Free up any pending old buffers before queueing new ones.
> */
> - free_old_xmit_skbs(vi);
> -
> /* Try to transmit */
> capacity = xmit_skb(vi, skb);
>
> @@ -605,6 +602,10 @@ static netdev_tx_t start_xmit(struct sk_buff
> *skb, struct net_device *dev)
> skb_orphan(skb);
> nf_reset(skb);
>
> + /* Free up any old buffers so we can queue new ones. */
> + if (capacity < 2+MAX_SKB_FRAGS)
> + capacity += free_old_xmit_skbs(vi);
> +
> /* Apparently nice girls don't return TX_BUSY; stop the queue
> * before it gets out of hand. Naturally, this wastes
> entries. */
> if (capacity < 2+MAX_SKB_FRAGS) {
I tried a similar patch before, it didn't help much on TCP stream
performance. But I didn't try multiple stream TCP_RR.
Shirley
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