[ovs-dev,5/8] netdev-dpdk: Add netdev_dpdk_vhost_txq_drain function.

Add netdev_dpdk_vhost_txq_drain(), that flushes packets on vHost User
port queues. Also add netdev_dpdk_vhost_tx_burst() function that
uses rte_vhost_enqueue_burst() to enqueue burst of packets on vHost User
ports.

Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
Signed-off-by: Antonio Fischetti <antonio.fischetti@intel.com>
Co-authored-by: Antonio Fischetti <antonio.fischetti@intel.com>
---
 lib/netdev-dpdk.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

On 07/06/17 11:21, Bhanuprakash Bodireddy wrote:
> Add netdev_dpdk_vhost_txq_drain(), that flushes packets on vHost User
> port queues. Also add netdev_dpdk_vhost_tx_burst() function that
> uses rte_vhost_enqueue_burst() to enqueue burst of packets on vHost User
> ports.
>
> Signed-off-by: Bhanuprakash Bodireddy <bhanuprakash.bodireddy@intel.com>
> Signed-off-by: Antonio Fischetti <antonio.fischetti@intel.com>
> Co-authored-by: Antonio Fischetti <antonio.fischetti@intel.com>
> ---
>   lib/netdev-dpdk.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 65 insertions(+), 2 deletions(-)
>
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index 4a9d9aa..dfaa3cd 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -308,10 +308,15 @@ struct dpdk_tx_queue {
>                                       * to enabled by guest. */
>       int count;                     /* Number of buffered packets waiting to
>                                         be sent. */
> +    int vhost_pkt_cnt;             /* Number of buffered packets waiting to
> +                                      be sent on vhost port */
>       struct rte_mbuf *burst_pkts[INTERIM_QUEUE_BURST_THRESHOLD];
>                                      /* Intermediate queue where packets can
>                                       * be buffered to amortize the cost of MMIO
>                                       * writes. */
> +    struct dp_packet *pkts[INTERIM_QUEUE_BURST_THRESHOLD];
> +                                   /* Intermediate queue where packets can
> +
Does it make sense to create a union for buffers and count, as the type 
is not shared on the given port?
We also need some consistent naming, i.e count vs vhost_pkt_cnt, and 
burst_pkts vs pkts.

>                                    * be buffered for vhost ports */
>   };
>   
>   /* dpdk has no way to remove dpdk ring ethernet devices
> @@ -1714,6 +1719,63 @@ netdev_dpdk_vhost_update_tx_counters(struct netdev_stats *stats,
>       }
>   }
>   
> +static int
> +netdev_dpdk_vhost_tx_burst(struct netdev_dpdk *dev, int qid)
> +{
> +    struct dpdk_tx_queue *txq = &dev->tx_q[qid];
> +    struct rte_mbuf **cur_pkts = (struct rte_mbuf **)txq->pkts;
> +
> +    int tx_vid = netdev_dpdk_get_vid(dev);
> +    int tx_qid = qid * VIRTIO_QNUM + VIRTIO_RXQ;
> +    uint32_t sent = 0;
> +    uint32_t retries = 0;
> +    uint32_t sum, total_pkts;
> +
> +    total_pkts = sum = txq->vhost_pkt_cnt;
> +    do {
> +        uint32_t ret;
> +        ret = rte_vhost_enqueue_burst(tx_vid, tx_qid, &cur_pkts[sent], sum);
> +        if (OVS_UNLIKELY(!ret)) {
> +            /* No packets enqueued - do not retry. */
> +            break;
> +        } else {
> +            /* Packet have been sent */
> +            sent += ret;
> +
> +            /* 'sum; packet have to be retransmitted */
> +            sum -= ret;
> +        }
> +    } while (sum && (retries++ < VHOST_ENQ_RETRY_NUM));
> +
> +    for (int i=0; i < total_pkts; i++) {
> +        dp_packet_delete(txq->pkts[i]);
> +    }
> +
> +    /* Reset pkt count */
> +    txq->vhost_pkt_cnt = 0;
> +
> +    /* 'sum' refers to packets dropped */
> +    return sum;
> +}
> +
> +/* Drain the txq if there are any packets available.
> + * dynamic_txqs/concurrent_txq is disabled for vHost User ports as
> + * 'OVS_VHOST_MAX_QUEUE_NUM[1024]' txqs are preallocated.
> + */
> +static int
> +netdev_dpdk_vhost_txq_drain(struct netdev *netdev, int qid,
> +                            bool concurrent_txq OVS_UNUSED)
> +{
> +    struct netdev_dpdk *dev = netdev_dpdk_cast(netdev);
> +    struct dpdk_tx_queue *txq = &dev->tx_q[qid];
> +
> +    if (OVS_LIKELY(txq->vhost_pkt_cnt)) {
> +        netdev_dpdk_vhost_tx_burst(dev, qid);
> +    }
> +
> +    return 0;
> +}
> +
>   static void
>   __netdev_dpdk_vhost_send(struct netdev *netdev, int qid,
>                            struct dp_packet **pkts, int cnt)
> @@ -3425,7 +3487,8 @@ static const struct netdev_class dpdk_vhost_class =
>           NULL,
>           netdev_dpdk_vhost_reconfigure,
>           netdev_dpdk_vhost_rxq_recv,
> -        NULL);
> +        netdev_dpdk_vhost_txq_drain);
> +
>   static const struct netdev_class dpdk_vhost_client_class =
>       NETDEV_DPDK_CLASS(
>           "dpdkvhostuserclient",
> @@ -3441,7 +3504,7 @@ static const struct netdev_class dpdk_vhost_client_class =
>           NULL,
>           netdev_dpdk_vhost_client_reconfigure,
>           netdev_dpdk_vhost_rxq_recv,
> -        NULL);
> +        netdev_dpdk_vhost_txq_drain);
>   
>   void
>   netdev_dpdk_register(void)