Hi Sivaprasad,
On 4/28/20 11:52 AM, Sivaprasad Tummala wrote:
> vhost buffer allocation is successful for packets that fit
> into a linear buffer. If it fails, vhost library is expected
> to drop the current buffer descriptor and skip to the next.
>
> The patch fixes the error scenario by skipping to next descriptor.
> Note: Drop counters are not currently supported.
Fixes tag is missing here, and sta...@dpdk.org should be cc'ed if
necessary.
> Signed-off-by: Sivaprasad Tummala <sivaprasad.tumm...@intel.com>
> ---
> lib/librte_vhost/virtio_net.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 37c47c7dc..b0d3a85c2 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -1688,6 +1688,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> {
You only fix split ring path, but not packed ring.
> uint16_t i;
> uint16_t free_entries;
> + uint16_t dropped = 0;
>
> if (unlikely(dev->dequeue_zero_copy)) {
> struct zcopy_mbuf *zmbuf, *next;
> @@ -1751,8 +1752,19 @@ virtio_dev_tx_split(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> update_shadow_used_ring_split(vq, head_idx, 0);
>
> pkts[i] = virtio_dev_pktmbuf_alloc(dev, mbuf_pool, buf_len);
> - if (unlikely(pkts[i] == NULL))
> + if (unlikely(pkts[i] == NULL)) {
> + /*
> + * mbuf allocation fails for jumbo packets with
> + * linear buffer flag set. Drop this packet and
> + * proceed with the next available descriptor to
> + * avoid HOL blocking
> + */
> + VHOST_LOG_DATA(WARNING,
> + "Failed to allocate memory for mbuf. Packet
> dropped!\n");
I think we need a better logging, otherwise it is going to flood the log
file quite rapidly if issue happens. Either some rate-limited logging or
warn-once would be better.
The warning message could be also improved, because when using linear
buffers, one would expect that the size of the mbufs could handle a
jumbo frame. So it should differentiate two
> + dropped += 1;
> + i++;
> break;
> + }
>
> err = copy_desc_to_mbuf(dev, vq, buf_vec, nr_vec, pkts[i],
> mbuf_pool);
> @@ -1796,7 +1808,7 @@ virtio_dev_tx_split(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> }
> }
>
> - return i;
> + return (i - dropped);
> }
>
> static __rte_always_inline int
>
