> -----Original Message-----
> From: dev [mailto:dev-boun...@dpdk.org] On Behalf Of Tiwei Bie
> Sent: Wednesday, June 20, 2018 3:41 PM
> To: Liu, Yong <yong....@intel.com>
> Cc: maxime.coque...@redhat.com; Wang, Zhihong <zhihong.w...@intel.com>;
> dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH 5/7] net/virtio: support IN_ORDER Rx and Tx
> 
> On Fri, Jun 08, 2018 at 05:07:22PM +0800, Marvin Liu wrote:
> > IN_ORDER Rx function can support merge-able feature. Descriptors
> > allocation and free will be done in bulk.
> >
> > Virtio dequeue logic:
> >     dequeue_burst_rx(burst mbufs)
> >     for (each mbuf b) {
> >             if (b need merge) {
> >                     merge remained mbufs
> >                     add merged mbuf to return mbufs list
> >             } else {
> >                     add mbuf to return mbufs list
> >             }
> >     }
> >     if (last mbuf c need merge) {
> >             dequeue_burst_rx(required mbufs)
> >             merge last mbuf c
> >     }
> >     refill_avail_ring_bulk()
> >     update_avail_ring()
> >     return mbufs list
> >
> > IN_ORDER Tx function can support indirect and offloading features.
> >
> > Virtio enqueue logic:
> >     xmit_cleanup(used descs)
> >     for (each xmit mbuf b) {
> >             if (b can inorder xmit) {
> >                     add mbuf b to inorder burst list
> >             } else {
> >                     xmit inorder burst list
> >                     xmit mbuf b with normal xmit
> >             }
> >     }
> >     if (inorder burst list not empty) {
> >             xmit inorder burst list
> >     }
> >     update_avail_ring()
> >
> > Signed-off-by: Marvin Liu <yong....@intel.com>
> >
> > diff --git a/drivers/net/virtio/virtio_ethdev.h
> b/drivers/net/virtio/virtio_ethdev.h
> > index bb40064ea..25697c872 100644
> > --- a/drivers/net/virtio/virtio_ethdev.h
> > +++ b/drivers/net/virtio/virtio_ethdev.h
> > @@ -83,9 +83,15 @@ uint16_t virtio_recv_pkts(void *rx_queue, struct
> rte_mbuf **rx_pkts,
> >  uint16_t virtio_recv_mergeable_pkts(void *rx_queue, struct rte_mbuf
> **rx_pkts,
> >             uint16_t nb_pkts);
> >
> > +uint16_t virtio_recv_inorder_pkts(void *rx_queue, struct rte_mbuf
> **rx_pkts,
> > +           uint16_t nb_pkts);
> > +
> >  uint16_t virtio_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
> >             uint16_t nb_pkts);
> >
> > +uint16_t virtio_xmit_inorder_pkts(void *tx_queue, struct rte_mbuf
> **tx_pkts,
> > +           uint16_t nb_pkts);
> > +
> >  uint16_t virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> >             uint16_t nb_pkts);
> >
> > diff --git a/drivers/net/virtio/virtio_rxtx.c
> b/drivers/net/virtio/virtio_rxtx.c
> > index 0bca29855..d0473d6b4 100644
> > --- a/drivers/net/virtio/virtio_rxtx.c
> > +++ b/drivers/net/virtio/virtio_rxtx.c
> > @@ -122,6 +122,45 @@ virtqueue_dequeue_burst_rx(struct virtqueue *vq,
> struct rte_mbuf **rx_pkts,
> >     return i;
> >  }
> >
> > +static uint16_t
> > +virtqueue_dequeue_inorder_rx(struct virtqueue *vq,
> 
> virtqueue_dequeue_burst_rx_inorder() will be better.
> 
> > +                   struct rte_mbuf **rx_pkts,
> > +                   uint32_t *len,
> > +                   uint16_t num)
> > +{
> > +   struct vring_used_elem *uep;
> > +   struct rte_mbuf *cookie;
> > +   uint16_t used_idx;
> > +   uint16_t i;
> > +
> > +   if (unlikely(num == 0))
> > +           return 0;
> > +
> > +   used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
> 
> Above assignment is misleading.
> 
> > +   for (i = 0; i < num; i++) {
> > +           used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
> > +           /* Desc idx same as used idx */
> > +           uep = &vq->vq_ring.used->ring[used_idx];
> > +           len[i] = uep->len;
> > +           cookie = (struct rte_mbuf *)vq->vq_descx[used_idx].cookie;
> > +
> > +           if (unlikely(cookie == NULL)) {
> > +                   PMD_DRV_LOG(ERR, "vring descriptor with no mbuf cookie
> at %u",
> > +                           vq->vq_used_cons_idx);
> > +                   break;
> > +           }
> > +
> > +           rte_prefetch0(cookie);
> > +           rte_packet_prefetch(rte_pktmbuf_mtod(cookie, void *));
> > +           rx_pkts[i]  = cookie;
> > +           vq->vq_used_cons_idx++;
> > +           vq->vq_descx[used_idx].cookie = NULL;
> > +   }
> > +
> > +   vq_ring_free_inorder(vq, used_idx, i);
> > +   return i;
> > +}
> > +
> >  #ifndef DEFAULT_TX_FREE_THRESH
> >  #define DEFAULT_TX_FREE_THRESH 32
> >  #endif
> > @@ -150,6 +189,70 @@ virtio_xmit_cleanup(struct virtqueue *vq, uint16_t
> num)
> >     }
> >  }
> >
> > +/* Cleanup from completed inorder transmits. */
> > +static void
> > +virtio_xmit_cleanup_inorder(struct virtqueue *vq, uint16_t num)
> > +{
> > +   uint16_t i, used_idx;
> > +
> > +   used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
> 
> Above assignment is misleading.
> 
> > +   for (i = 0; i < num; i++) {
> > +           struct vq_desc_extra *dxp;
> > +
> > +           used_idx = vq->vq_used_cons_idx & (vq->vq_nentries - 1);
> > +           dxp = &vq->vq_descx[used_idx];
> > +           vq->vq_used_cons_idx++;
> > +
> > +           if (dxp->cookie != NULL) {
> > +                   rte_pktmbuf_free(dxp->cookie);
> > +                   dxp->cookie = NULL;
> > +           }
> > +   }
> > +   vq_ring_free_inorder(vq, used_idx, num);
> 
> If num is zero, we can't free used_idx.
> 
> > +}
> > +
> > +static inline int
> > +virtqueue_enqueue_inorder_refill(struct virtqueue *vq,
> 
> virtqueue_enqueue_recv_refill_inorder() will be better.
> 
> 
> > +                   struct rte_mbuf **cookies,
> > +                   uint16_t num)
> > +{
> > +   struct vq_desc_extra *dxp;
> > +   struct virtio_hw *hw = vq->hw;
> > +   struct vring_desc *start_dp;
> > +   uint16_t head_idx, idx, i = 0;
> > +
> > +   if (unlikely(vq->vq_free_cnt == 0))
> > +           return -ENOSPC;
> > +   if (unlikely(vq->vq_free_cnt < num))
> > +           return -EMSGSIZE;
> > +
> > +   head_idx = vq->vq_desc_head_idx & (vq->vq_nentries - 1);
> > +   start_dp = vq->vq_ring.desc;
> > +
> > +   while (i < num) {
> > +           idx = head_idx & (vq->vq_nentries - 1);
> > +           dxp = &vq->vq_descx[idx];
> > +           dxp->cookie = (void *)(struct rte_mbuf *)cookies[i];
> 
> Casting isn't necessary.
> 
> > +           dxp->ndescs = 1;
> > +
> > +           start_dp[idx].addr =
> > +                           VIRTIO_MBUF_ADDR(cookies[i], vq) +
> > +                           RTE_PKTMBUF_HEADROOM - hw->vtnet_hdr_size;
> > +           start_dp[idx].len =
> > +                           cookies[i]->buf_len -
> > +                           RTE_PKTMBUF_HEADROOM +
> > +                           hw->vtnet_hdr_size;
> > +           start_dp[idx].flags =  VRING_DESC_F_WRITE;
> > +
> > +           head_idx++;
> > +           i++;
> > +   }
> > +
> > +   vq->vq_avail_idx += num;
> > +   vq->vq_desc_head_idx += num;
> > +   vq->vq_free_cnt = (uint16_t)(vq->vq_free_cnt - num);
> > +   return 0;
> > +}
> >
> >  static inline int
> >  virtqueue_enqueue_recv_refill(struct virtqueue *vq, struct rte_mbuf
> *cookie)
> > @@ -246,9 +349,113 @@ tx_offload_enabled(struct virtio_hw *hw)
> >             (var) = (val);                  \
> >  } while (0)
> >
> [...]
> > +
> > +static void
> > +virtio_discard_inorder_rxbuf(struct virtqueue *vq, struct rte_mbuf *m)
> 
> virtio_discard_rxbuf_inorder() will be better.
> 
> > +{
> > +   int error;
> > +
> > +   error = virtqueue_enqueue_inorder_refill(vq, &m, 1);
> >     if (unlikely(error)) {
> >             RTE_LOG(ERR, PMD, "cannot requeue discarded mbuf");
> >             rte_pktmbuf_free(m);
> > @@ -813,6 +1002,191 @@ virtio_recv_pkts(void *rx_queue, struct rte_mbuf
> **rx_pkts, uint16_t nb_pkts)
> >     return nb_rx;
> >  }
> >
> > +uint16_t
> > +virtio_recv_inorder_pkts(void *rx_queue,
> 
> virtio_recv_mergeable_pkts_inorder() will be better.
> 
> > +                   struct rte_mbuf **rx_pkts,
> > +                   uint16_t nb_pkts)
> > +{
> > +   struct virtnet_rx *rxvq = rx_queue;
> > +   struct virtqueue *vq = rxvq->vq;
> > +   struct virtio_hw *hw = vq->hw;
> > +   struct rte_mbuf *rxm;
> > +   struct rte_mbuf *prev;
> > +   uint16_t nb_used, num, nb_rx;
> > +   uint32_t len[VIRTIO_MBUF_BURST_SZ];
> > +   struct rte_mbuf *rcv_pkts[VIRTIO_MBUF_BURST_SZ];
> > +   int error;
> > +   uint32_t i, nb_enqueued;
> > +   uint32_t seg_num;
> > +   uint32_t seg_res;
> > +   uint32_t hdr_size;
> > +   int offload;
> > +
> > +   nb_rx = 0;
> > +   if (unlikely(hw->started == 0))
> > +           return nb_rx;
> > +
> > +   nb_used = VIRTQUEUE_NUSED(vq);
> > +   nb_used = RTE_MIN(nb_used, nb_pkts);
> > +   nb_used = RTE_MIN(nb_used, VIRTIO_MBUF_BURST_SZ);
> > +
> > +   virtio_rmb();
> > +
> > +   PMD_RX_LOG(DEBUG, "used:%d", nb_used);
> > +
> > +   i = 0;
> > +   nb_enqueued = 0;
> > +   seg_num = 1;
> > +   seg_res = 0;
> > +   hdr_size = hw->vtnet_hdr_size;
> > +   offload = rx_offload_enabled(hw);
> > +
> > +   num = virtqueue_dequeue_inorder_rx(vq, rcv_pkts, len, nb_used);
> > +
> > +   for (; i < num; i++) {
> 
> Why not initialize i in for ()?
> 
> > +           struct virtio_net_hdr_mrg_rxbuf *header;
> > +
> > +           PMD_RX_LOG(DEBUG, "dequeue:%d", num);
> > +           PMD_RX_LOG(DEBUG, "packet len:%d", len[i]);
> > +
> > +           rxm = rcv_pkts[i];
> > +
> > +           if (unlikely(len[i] < hdr_size + ETHER_HDR_LEN)) {
> > +                   PMD_RX_LOG(ERR, "Packet drop");
> > +                   nb_enqueued++;
> > +                   virtio_discard_inorder_rxbuf(vq, rxm);
> > +                   rxvq->stats.errors++;
> > +                   continue;
> > +           }
> > +
> > +           header = (struct virtio_net_hdr_mrg_rxbuf *)((char *)rxm-
> >buf_addr +
> > +                   RTE_PKTMBUF_HEADROOM - hdr_size);
> > +           seg_num = header->num_buffers;
> > +
> > +           if (seg_num == 0)
> > +                   seg_num = 1;
> > +
> > +           rxm->data_off = RTE_PKTMBUF_HEADROOM;
> > +           rxm->nb_segs = seg_num;
> > +           rxm->ol_flags = 0;
> > +           rxm->vlan_tci = 0;
> > +           rxm->pkt_len = (uint32_t)(len[i] - hdr_size);
> > +           rxm->data_len = (uint16_t)(len[i] - hdr_size);
> > +
> > +           rxm->port = rxvq->port_id;
> > +
> > +           rx_pkts[nb_rx] = rxm;
> > +           prev = rxm;
> > +
> > +           if (offload && virtio_rx_offload(rxm, &header->hdr) < 0) {
> > +                   virtio_discard_inorder_rxbuf(vq, rxm);
> > +                   rxvq->stats.errors++;
> > +                   continue;
> > +           }
> > +
> > +           seg_res = seg_num - 1;
> > +
> > +           /* Merge remaining segments */
> > +           while (seg_res != 0 && i < num) {
> > +                   rxm = rcv_pkts[i];
> > +                   rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
> > +                   rxm->pkt_len = (uint32_t)(len[i]);
> > +                   rxm->data_len = (uint16_t)(len[i]);
> > +
> > +                   rx_pkts[nb_rx]->pkt_len += (uint32_t)(len[i]);
> > +                   rx_pkts[nb_rx]->data_len += (uint16_t)(len[i]);
> > +
> > +                   i++;
> > +
> > +                   if (prev)
> > +                           prev->next = rxm;
> > +
> > +                   prev = rxm;
> > +                   seg_res -= 1;
> > +           }
> > +
> > +           if (hw->vlan_strip)
> > +                   rte_vlan_strip(rx_pkts[nb_rx]);
> > +
> > +           VIRTIO_DUMP_PACKET(rx_pkts[nb_rx],
> > +                   rx_pkts[nb_rx]->data_len);
> > +
> > +           rxvq->stats.bytes += rx_pkts[nb_rx]->pkt_len;
> > +           virtio_update_packet_stats(&rxvq->stats, rx_pkts[nb_rx]);
> 
> When seg_res != 0, we cannot run above code.
> 
> > +           nb_rx++;
> > +   }
> > +
> > +   /* Last packet still need merge segments */
> > +   while (seg_res != 0) {
> > +           uint16_t rcv_cnt = RTE_MIN((uint16_t)seg_res,
> > +                                   VIRTIO_MBUF_BURST_SZ);
> > +
> > +           prev = rcv_pkts[nb_rx - 1];
> > +           if (likely(VIRTQUEUE_NUSED(vq) >= rcv_cnt)) {
> > +                   num = virtqueue_dequeue_inorder_rx(vq, rcv_pkts, len,
> > +                                                      rcv_cnt);
> > +                   uint16_t extra_idx = 0;
> > +
> > +                   rcv_cnt = num;
> > +                   while (extra_idx < rcv_cnt) {
> > +                           rxm = rcv_pkts[extra_idx];
> > +                           rxm->data_off = RTE_PKTMBUF_HEADROOM - hdr_size;
> > +                           rxm->pkt_len = (uint32_t)(len[extra_idx]);
> > +                           rxm->data_len = (uint16_t)(len[extra_idx]);
> > +                           prev->next = rxm;
> > +                           prev = rxm;
> > +                           rx_pkts[nb_rx - 1]->pkt_len += len[extra_idx];
> > +                           rx_pkts[nb_rx - 1]->data_len += len[extra_idx];
> > +                           extra_idx += 1;
> > +                   };
> > +                   seg_res -= rcv_cnt;
> > +           } else {
> > +                   PMD_RX_LOG(ERR,
> > +                                   "No enough segments for packet.");
> > +                   virtio_discard_inorder_rxbuf(vq, prev);
> > +                   rxvq->stats.errors++;
> > +                   nb_rx--;
> > +                   break;
> > +           }
> > +   }
> > +
> > +   rxvq->stats.packets += nb_rx;
> > +
> > +   /* Allocate new mbuf for the used descriptor */
> > +   error = ENOSPC;
> 
> Above assignment is meaningless.

Thanks, Will remove it in V2. 


> 
> > +
> > +   if (likely(!virtqueue_full(vq))) {
> > +           /* free_cnt may include mrg descs */
> > +           uint16_t free_cnt = vq->vq_free_cnt;
> > +           struct rte_mbuf *new_pkts[free_cnt];
> > +
> > +           if (!rte_pktmbuf_alloc_bulk(rxvq->mpool, new_pkts, free_cnt))
> {
> > +                   error = virtqueue_enqueue_inorder_refill(vq, new_pkts,
> > +                                   free_cnt);
> > +                   if (unlikely(error)) {
> > +                           for (i = 0; i < free_cnt; i++)
> > +                                   rte_pktmbuf_free(new_pkts[i]);
> > +                   }
> > +                   nb_enqueued += free_cnt;
> > +           } else {
> > +                   struct rte_eth_dev *dev
> > +                           = &rte_eth_devices[rxvq->port_id];
> > +                   dev->data->rx_mbuf_alloc_failed += free_cnt;
> > +           }
> > +   }
> > +
> > +   if (likely(nb_enqueued)) {
> > +           vq_update_avail_idx(vq);
> > +
> > +           if (unlikely(virtqueue_kick_prepare(vq))) {
> > +                   virtqueue_notify(vq);
> > +                   PMD_RX_LOG(DEBUG, "Notified");
> > +           }
> > +   }
> > +
> > +   return nb_rx;
> > +}
> > +
> >  uint16_t
> >  virtio_recv_mergeable_pkts(void *rx_queue,
> >                     struct rte_mbuf **rx_pkts,
> > @@ -1060,7 +1434,8 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf
> **tx_pkts, uint16_t nb_pkts)
> >             }
> >
> >             /* Enqueue Packet buffers */
> > -           virtqueue_enqueue_xmit(txvq, txm, slots, use_indirect,
> can_push);
> > +           virtqueue_enqueue_xmit(txvq, txm, slots, use_indirect,
> > +                   can_push, 0);
> >
> >             txvq->stats.bytes += txm->pkt_len;
> >             virtio_update_packet_stats(&txvq->stats, txm);
> > @@ -1079,3 +1454,121 @@ virtio_xmit_pkts(void *tx_queue, struct rte_mbuf
> **tx_pkts, uint16_t nb_pkts)
> >
> >     return nb_tx;
> >  }
> > +
> > +uint16_t
> > +virtio_xmit_inorder_pkts(void *tx_queue,
> 
> virtio_xmit_pkts_inorder() will be better.
> 
> > +                   struct rte_mbuf **tx_pkts,
> > +                   uint16_t nb_pkts)
> > +{
> > +   struct virtnet_tx *txvq = tx_queue;
> > +   struct virtqueue *vq = txvq->vq;
> > +   struct virtio_hw *hw = vq->hw;
> > +   uint16_t hdr_size = hw->vtnet_hdr_size;
> > +   uint16_t nb_used, nb_avail, nb_tx = 0, inorder_tx = 0;
> > +   struct rte_mbuf *inorder_pkts[nb_pkts];
> > +   int error;
> > +
> > +   if (unlikely(hw->started == 0 && tx_pkts != hw->inject_pkts))
> > +           return nb_tx;
> > +
> > +   if (unlikely(nb_pkts < 1))
> > +           return nb_pkts;
> > +
> > +   VIRTQUEUE_DUMP(vq);
> > +   PMD_TX_LOG(DEBUG, "%d packets to xmit", nb_pkts);
> > +   nb_used = VIRTQUEUE_NUSED(vq);
> > +
> > +   virtio_rmb();
> > +   if (likely(nb_used > vq->vq_nentries - vq->vq_free_thresh))
> > +           virtio_xmit_cleanup_inorder(vq, nb_used);
> > +
> > +   nb_avail = RTE_MIN(vq->vq_free_cnt, nb_pkts);
> > +
> > +   for (nb_tx = 0; nb_tx < nb_avail; nb_tx++) {
> > +           struct rte_mbuf *txm = tx_pkts[nb_tx];
> > +           int slots, need;
> > +           int can_push = 0, use_indirect = 0, flush_inorder = 1;
> > +
> > +           /* Do VLAN tag insertion */
> > +           if (unlikely(txm->ol_flags & PKT_TX_VLAN_PKT)) {
> > +                   error = rte_vlan_insert(&txm);
> > +                   if (unlikely(error)) {
> > +                           rte_pktmbuf_free(txm);
> > +                           continue;
> > +                   }
> > +           }
> > +
> > +           txvq->stats.bytes += txm->pkt_len;
> > +           virtio_update_packet_stats(&txvq->stats, txm);
> > +
> > +           /* optimize ring usage */
> > +           if ((vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) ||
> > +                vtpci_with_feature(hw, VIRTIO_F_VERSION_1)) &&
> > +                rte_mbuf_refcnt_read(txm) == 1 &&
> > +                RTE_MBUF_DIRECT(txm) &&
> > +                txm->nb_segs == 1 &&
> > +                rte_pktmbuf_headroom(txm) >= hdr_size &&
> > +                rte_is_aligned(rte_pktmbuf_mtod(txm, char *),
> > +                           __alignof__(struct virtio_net_hdr_mrg_rxbuf))) {
> > +                   can_push = 1;
> 
> There is no need to have 'can_push' any more.
> 
> > +
> > +                   inorder_pkts[inorder_tx] = txm;
> > +                   inorder_tx++;
> 
> inorder_tx isn't a good name.
> 
> > +                   flush_inorder = 0;
> 
> I think there is no need to introduce 'flush_inorder'.
> And it will make the code much more readable by writing
> the code like:
> 
>       for (nb_tx = 0; nb_tx < nb_avail; nb_tx++) {
>               struct rte_mbuf *txm = tx_pkts[nb_tx];
> 
>               ......
> 
>               if ((vtpci_with_feature(hw, VIRTIO_F_ANY_LAYOUT) ||
>                    vtpci_with_feature(hw, VIRTIO_F_VERSION_1)) &&
>                    rte_mbuf_refcnt_read(txm) == 1 &&
>                    RTE_MBUF_DIRECT(txm) &&
>                    txm->nb_segs == 1 &&
>                    rte_pktmbuf_headroom(txm) >= hdr_size &&
>                    rte_is_aligned(rte_pktmbuf_mtod(txm, char *),
>                               __alignof__(struct virtio_net_hdr_mrg_rxbuf))) {
> 
>                       inorder_pkts[nb_inorder_pkts++] = txm;
>                       continue;
>               }
> 
>               /* Flush inorder packets if any. */
>               if (nb_inorder_pkts) {
>                       virtqueue_enqueue_xmit_inorder(txvq, inorder_pkts,
>                               nb_inorder_pkts);
>                       nb_inorder_pkts = 0;
>               }
> 
>               ......
> 
>               virtqueue_enqueue_xmit(txvq, txm, slots, 0, 0, 1);
>       }

Thanks Tiwei, this logic is more clear. Will modified in V2.

> 
>       /* Flush inorder packets if any. */
>       if (nb_inorder_pkts) {
>               virtqueue_enqueue_xmit_inorder(txvq, inorder_pkts,
>                       nb_inorder_pkts);
>               nb_inorder_pkts = 0;
>       }
> 
> 
> 
> > +           } else if (vtpci_with_feature(hw, VIRTIO_RING_F_INDIRECT_DESC)
> &&
> > +                           txm->nb_segs < VIRTIO_MAX_TX_INDIRECT) {
> > +                   use_indirect = 1;
> > +           }
> 
> There is no need to try to use INDIRECT.
> 
> > +
> > +           if (flush_inorder) {
> > +                   /* Flush inorder packets */
> > +                   virtqueue_enqueue_xmit_inorder(txvq, inorder_pkts,
> > +                           inorder_tx);
> > +                   inorder_tx = 0;
> > +
> > +                   /* How many main ring entries are needed to this Tx?
> > +                    * any_layout => number of segments
> > +                    * indirect   => 1
> > +                    * default    => number of segments + 1
> > +                    */
> > +                   slots = use_indirect ? 1 : (txm->nb_segs + !can_push);
> > +                   need = slots - vq->vq_free_cnt;
> > +
> > +                   if (unlikely(need > 0)) {
> > +                           nb_used = VIRTQUEUE_NUSED(vq);
> > +                           virtio_rmb();
> > +                           need = RTE_MIN(need, (int)nb_used);
> > +
> > +                           virtio_xmit_cleanup_inorder(vq, need);
> > +                           need = slots - vq->vq_free_cnt;
> > +                           if (unlikely(need > 0)) {
> > +                                   PMD_TX_LOG(ERR,
> > +                                           "No free tx descriptors to 
> > transmit");
> > +                                   break;
> > +                           }
> > +                   }
> > +                   /* Enqueue Packet buffers */
> > +                   virtqueue_enqueue_xmit(txvq, txm, slots, use_indirect,
> > +                           can_push, 1);
> > +           }
> > +   }
> > +
> > +   /* Transmit all inorder packets */
> > +   if (inorder_tx)
> > +           virtqueue_enqueue_xmit_inorder(txvq, inorder_pkts, inorder_tx);
> > +
> > +   txvq->stats.packets += nb_tx;
> > +
> > +   if (likely(nb_tx)) {
> > +           vq_update_avail_idx(vq);
> > +
> > +           if (unlikely(virtqueue_kick_prepare(vq))) {
> > +                   virtqueue_notify(vq);
> > +                   PMD_TX_LOG(DEBUG, "Notified backend after xmit");
> > +           }
> > +   }
> > +
> > +   VIRTQUEUE_DUMP(vq);
> > +
> > +   return nb_tx;
> > +}
> > --
> > 2.17.0
> >

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