On 11/26/2015 1:33 AM, Xie, Huawei wrote:
> On 11/13/2015 5:33 PM, Tom Kiely wrote:
>> If all rx descriptors are processed while transient
>> mbuf exhaustion is present, the rx ring ends up with
>> no available descriptors. Thus no packets are received
>> on that ring. Since descriptor refill is performed post
>> rx descriptor processing, in this case no refill is
>> ever subsequently performed resulting in permanent rx
>> traffic drop.
>>
>> Signed-off-by: Tom Kiely <tkiely at brocade.com>
>> ---
>> drivers/net/virtio/virtio_rxtx.c | 6 ++++--
>> 1 file changed, 4 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/net/virtio/virtio_rxtx.c
>> b/drivers/net/virtio/virtio_rxtx.c
>> index 5770fa2..a95e234 100644
>> --- a/drivers/net/virtio/virtio_rxtx.c
>> +++ b/drivers/net/virtio/virtio_rxtx.c
>> @@ -586,7 +586,8 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf
>> **rx_pkts, uint16_t nb_pkts)
>> if (likely(num > DESC_PER_CACHELINE))
>> num = num - ((rxvq->vq_used_cons_idx + num) %
>> DESC_PER_CACHELINE);
>>
>> - if (num == 0)
>> + /* Refill free descriptors even if no pkts recvd */
>> + if (num == 0 && virtqueue_full(rxvq))
> Should the return condition be that no used buffers and we have avail
> descs in avail ring, i.e,
> num == 0 && rxvq->vq_free_cnt != rxvq->vq_nentries
>
> rather than
> num == 0 && rxvq->vq_free_cnt == 0
> ?
Tom:
Any further progress?
>> return 0;
>>
>> num = virtqueue_dequeue_burst_rx(rxvq, rcv_pkts, len, num);
>> @@ -683,7 +684,8 @@ virtio_recv_mergeable_pkts(void *rx_queue,
>>
>> virtio_rmb();
>>
>> - if (nb_used == 0)
>> + /* Refill free descriptors even if no pkts recvd */
>> + if (nb_used == 0 && virtqueue_full(rxvq))
>> return 0;
>>
>> PMD_RX_LOG(DEBUG, "used:%d\n", nb_used);
>
