On Wed, Dec 06, 2017 at 07:23:11PM +0800, Tiwei Bie wrote:
> On Mon, Dec 04, 2017 at 06:02:08AM -0800, Xiao Wang wrote:
> [...]
> > diff --git a/drivers/net/virtio/virtio_rxtx.c
> > b/drivers/net/virtio/virtio_rxtx.c
> > index 6a24fde..7313bdd 100644
> > --- a/drivers/net/virtio/virtio_rxtx.c
> > +++ b/drivers/net/virtio/virtio_rxtx.c
> > @@ -1100,3 +1100,84 @@
> >
> > return nb_tx;
> > }
> > +
> > +uint16_t
> > +virtio_inject_pkts(void *tx_queue, 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_tx = 0;
> > +
> > + if (unlikely(nb_pkts < 1))
> > + return nb_pkts;
> > +
> > + 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(vq, nb_used);
> > +
> > + for (nb_tx = 0; nb_tx < nb_pkts; nb_tx++) {
> > + struct rte_mbuf *txm = tx_pkts[nb_tx];
> > + int can_push = 0, use_indirect = 0, slots, need;
> > +
> > + /* 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;
> > + else if (vtpci_with_feature(hw, VIRTIO_RING_F_INDIRECT_DESC) &&
> > + txm->nb_segs < VIRTIO_MAX_TX_INDIRECT)
> > + use_indirect = 1;
> > +
> > + /* 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;
> > +
> > + /* Positive value indicates it need free vring descriptors */
> > + if (unlikely(need > 0)) {
> > + nb_used = VIRTQUEUE_NUSED(vq);
> > + virtio_rmb();
> > + need = RTE_MIN(need, (int)nb_used);
> > +
> > + virtio_xmit_cleanup(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);
> > +
> > + txvq->stats.bytes += txm->pkt_len;
> > + virtio_update_packet_stats(&txvq->stats, txm);
> > + }
> > +
> > + 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");
> > + }
> > + }
> > +
> > + return nb_tx;
> > +}
>
> Simple Tx has some special assumptions and setups of the txq.
> Basically the current implementation of virtio_inject_pkts()
> is a mirror of virtio_xmit_pkts(). So when simple Tx function
> is chosen, calling virtio_inject_pkts() could cause problems.
That's why I suggested to invoke the tx_pkt_burst callback directly.
--yliu
