search for: xmit_tasklet

...the transmitting userspace could block with a full socket until the timer fired, the skb destructor was called, and they were re-woken. So we added the VIRTIO_F_NOTIFY_ON_EMPTY feature: supporting devices send an interrupt (even if normally suppressed) on an empty xmit ring which makes us schedule xmit_tasklet(). This was a benchmark win. Unfortunately, VIRTIO_F_NOTIFY_ON_EMPTY makes quite a lot of work: a host which is faster than the guest will fire the interrupt every xmit packet (slowing the guest down further). Attempting mitigation in the host adds overhead of userspace timers (possibly with the...

...the transmitting userspace could block with a full socket until the timer fired, the skb destructor was called, and they were re-woken. So we added the VIRTIO_F_NOTIFY_ON_EMPTY feature: supporting devices send an interrupt (even if normally suppressed) on an empty xmit ring which makes us schedule xmit_tasklet(). This was a benchmark win. Unfortunately, VIRTIO_F_NOTIFY_ON_EMPTY makes quite a lot of work: a host which is faster than the guest will fire the interrupt every xmit packet (slowing the guest down further). Attempting mitigation in the host adds overhead of userspace timers (possibly with the...

If we fail to transmit a packet, we assume the queue is full and put the skb into last_xmit_skb. However, if more space frees up before we xmit it, we loop, and the result can be transmitting the same skb twice. Fix is simple: set skb to NULL if we've used it in some way, and check before sending. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> --- drivers/net/virtio_net.c |

If we fail to transmit a packet, we assume the queue is full and put the skb into last_xmit_skb. However, if more space frees up before we xmit it, we loop, and the result can be transmitting the same skb twice. Fix is simple: set skb to NULL if we've used it in some way, and check before sending. Signed-off-by: Rusty Russell <rusty at rustcorp.com.au> --- drivers/net/virtio_net.c |

From: Mark McLoughlin <markmc at redhat.com> hdr->csum_start is the offset from the start of the ethernet header to the transport layer checksum field. skb->csum_start is the offset from skb->head. skb_partial_csum_set() assumes that skb->data points to the ethernet header - i.e. it computes skb->csum_start by adding the headroom to hdr->csum_start. Since

...: if there are no more packets - * queued, start_xmit won't be called. */ - tasklet_schedule(&vi->tasklet); + if (vi->free_in_tasklet) + tasklet_schedule(&vi->tasklet); } static void receive_skb(struct net_device *dev, struct sk_buff *skb, @@ -509,12 +505,7 @@ static void xmit_tasklet(unsigned long d struct virtnet_info *vi = (void *)data; netif_tx_lock_bh(vi->dev); - if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) { - vi->svq->vq_ops->kick(vi->svq); - vi->last_xmit_skb = NULL; - } - if (vi->free_in_tasklet) - free_old_x...

...: if there are no more packets - * queued, start_xmit won't be called. */ - tasklet_schedule(&vi->tasklet); + if (vi->free_in_tasklet) + tasklet_schedule(&vi->tasklet); } static void receive_skb(struct net_device *dev, struct sk_buff *skb, @@ -509,12 +505,7 @@ static void xmit_tasklet(unsigned long d struct virtnet_info *vi = (void *)data; netif_tx_lock_bh(vi->dev); - if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) { - vi->svq->vq_ops->kick(vi->svq); - vi->last_xmit_skb = NULL; - } - if (vi->free_in_tasklet) - free_old_x...

...->len) + 1; err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb); - if (!err && !vi->free_in_tasklet) + if (err >= 0 && !vi->free_in_tasklet) mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10)); return err; @@ -538,7 +538,7 @@ static void xmit_tasklet(unsigned long d struct virtnet_info *vi = (void *)data; netif_tx_lock_bh(vi->dev); - if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) { + if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) >= 0) { vi->svq->vq_ops->kick(vi->s...

...->len) + 1; err = vi->svq->vq_ops->add_buf(vi->svq, sg, num, 0, skb); - if (!err && !vi->free_in_tasklet) + if (err >= 0 && !vi->free_in_tasklet) mod_timer(&vi->xmit_free_timer, jiffies + (HZ/10)); return err; @@ -538,7 +538,7 @@ static void xmit_tasklet(unsigned long d struct virtnet_info *vi = (void *)data; netif_tx_lock_bh(vi->dev); - if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) == 0) { + if (vi->last_xmit_skb && xmit_skb(vi, vi->last_xmit_skb) >= 0) { vi->svq->vq_ops->kick(vi->s...