On Wed, Apr 29, 2020 at 10:43:01AM +0200, Maxime Coquelin wrote:
> 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.
In that case shouldn't we continue to process the ring?
Also, don't we have the same issue with copy_desc_to_mbuf()
and get_zmbuf()?
fbl
> 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
> >
>
--
fbl
