similar to: [PATCH] virtio_net: free transmit skbs in a timer

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 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 |

The virtio_net driver is complicated by the two methods of freeing old xmit buffers (in addition to freeing old ones at the start of the xmit path). The original code used a 1/10 second timer attached to xmit_free(), reset on every xmit. Before we orphaned skbs on xmit, the transmitting userspace could block with a full socket until the timer fired, the skb destructor was called, and they were

The virtio_net driver is complicated by the two methods of freeing old xmit buffers (in addition to freeing old ones at the start of the xmit path). The original code used a 1/10 second timer attached to xmit_free(), reset on every xmit. Before we orphaned skbs on xmit, the transmitting userspace could block with a full socket until the timer fired, the skb destructor was called, and they were

skb is only NULL the first time around: it's more correct to test for being under-budget. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> diff -r 2a94425ac7d5 drivers/net/virtio_net.c --- a/drivers/net/virtio_net.c Thu Nov 15 13:47:28 2007 +1100 +++ b/drivers/net/virtio_net.c Thu Nov 15 23:10:44 2007 +1100 @@ -198,8 +198,8 @@ again: if (vi->num < vi->max / 2)

skb is only NULL the first time around: it's more correct to test for being under-budget. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> diff -r 2a94425ac7d5 drivers/net/virtio_net.c --- a/drivers/net/virtio_net.c Thu Nov 15 13:47:28 2007 +1100 +++ b/drivers/net/virtio_net.c Thu Nov 15 23:10:44 2007 +1100 @@ -198,8 +198,8 @@ again: if (vi->num < vi->max / 2)

virtio net used to unlink skbs from send queues on error, but ever since 48925e372f04f5e35fec6269127c62b2c71ab794 we do not do this. This causes guest data corruption and crashes with vhost since net core can requeue the skb or free it without it being taken off the list. This patch fixes this by queueing the skb after successfull transmit. Signed-off-by: Michael S. Tsirkin <mst at

virtio net used to unlink skbs from send queues on error, but ever since 48925e372f04f5e35fec6269127c62b2c71ab794 we do not do this. This causes guest data corruption and crashes with vhost since net core can requeue the skb or free it without it being taken off the list. This patch fixes this by queueing the skb after successfull transmit. Signed-off-by: Michael S. Tsirkin <mst at

OK, here's a new attempt to use the new capacity api. I also added more comments to clarify the logic. Hope this is more readable. Let me know pls. This is on top of the patches applied by Rusty. Note: there are now actually 2 calls to fee_old_xmit_skbs on data path so instead of passing flag '2' to the second one I thought we can just make each call free up at least 1 skb. This

OK, here's a new attempt to use the new capacity api. I also added more comments to clarify the logic. Hope this is more readable. Let me know pls. This is on top of the patches applied by Rusty. Note: there are now actually 2 calls to fee_old_xmit_skbs on data path so instead of passing flag '2' to the second one I thought we can just make each call free up at least 1 skb. This

OK, here's a new attempt to use the new capacity api. I also added more comments to clarify the logic. Hope this is more readable. Let me know pls. This is on top of the patches applied by Rusty. Warning: untested. Posting now to give people chance to comment on the API. Changes from v1: - fix comment in patch 2 to correct confusion noted by Rusty - rewrite patch 3 along the lines

OK, here's a new attempt to use the new capacity api. I also added more comments to clarify the logic. Hope this is more readable. Let me know pls. This is on top of the patches applied by Rusty. Warning: untested. Posting now to give people chance to comment on the API. Changes from v1: - fix comment in patch 2 to correct confusion noted by Rusty - rewrite patch 3 along the lines

We check for finished xmit skbs on every xmit, or on a timer (unless the host promises to force an interrupt when the xmit ring is empty). This can penalize userspace tasks which fill their sockbuf. Not much difference with TSO, but measurable with large numbers of packets. There are a finite number of packets which can be in the transmission queue. We could fire the timer more than every

We check for finished xmit skbs on every xmit, or on a timer (unless the host promises to force an interrupt when the xmit ring is empty). This can penalize userspace tasks which fill their sockbuf. Not much difference with TSO, but measurable with large numbers of packets. There are a finite number of packets which can be in the transmission queue. We could fire the timer more than every

Currently, we store the statistics in the independent fields of virtnet_stats, this is not scalable when we want to add more counters. As suggested by Michael, this patch convert it to an array and use the enum as the index to access them. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/net/virtio_net.c | 30 +++++++++++++++++------------- 1 files changed, 17

Currently, we store the statistics in the independent fields of virtnet_stats, this is not scalable when we want to add more counters. As suggested by Michael, this patch convert it to an array and use the enum as the index to access them. Signed-off-by: Jason Wang <jasowang at redhat.com> --- drivers/net/virtio_net.c | 30 +++++++++++++++++------------- 1 files changed, 17

Satistics counters is useful for debugging and performance optimization, so this patch lets virtio_net driver collect following and export them to userspace through "ethtool -S": - number of packets sent/received - number of bytes sent/received - number of callbacks for tx/rx - number of kick for tx/rx - number of bytes/packets queued for tx As virtnet_stats were per-cpu, so both

Satistics counters is useful for debugging and performance optimization, so this patch lets virtio_net driver collect following and export them to userspace through "ethtool -S": - number of packets sent/received - number of bytes sent/received - number of callbacks for tx/rx - number of kick for tx/rx - number of bytes/packets queued for tx As virtnet_stats were per-cpu, so both

virtqueue ops were introduced in the hope that we'll have multiple implementations besides virtio_ring, but none have surfaced so far, and given that existing virtio ring is deployed in production we are likely stuck with it now, so this layer just adds complexity and overhead. Further, the need to pass vq twice to each call (as in dev->vq->vq_ops->kick(dev->vq) ) adds potential