Re: [dpdk-dev] [dpdk-stable] [PATCH 19.11 V2 08/12] virtio: fix rx stats with vectorized functions

[Thibaut Collet <thibaut.collet@6wind.com>]

On Thu, Aug 8, 2019 at 7:17 AM Tiwei Bie <tiwei.bie@intel.com> wrote:
>
> On Wed, Aug 07, 2019 at 05:09:17PM +0200, Thierry Herbelot wrote:
> > From: Thibaut Collet <thibaut.collet@6wind.com>
> >
> > With vectorized functions, only the rx stats for number of packets is
> > incremented.
> > Update also the other statistics.
> > Performance impact is about 2%
>
> Could you share some details about your performance test?

The test has been done with a 6wind application based on dpdk and I
have not keep details. With test pmd impact is maybe a little bit
higher.

>
>
> > diff --git a/drivers/net/virtio/virtio_rxtx_simple_sse.c b/drivers/net/virtio/virtio_rxtx_simple_sse.c
> > index af76708d66ae..c757e8c9d601 100644
> > --- a/drivers/net/virtio/virtio_rxtx_simple_sse.c
> > +++ b/drivers/net/virtio/virtio_rxtx_simple_sse.c
> > @@ -48,6 +48,7 @@ virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> >       struct vring_used_elem *rused;
> >       struct rte_mbuf **sw_ring;
> >       struct rte_mbuf **sw_ring_end;
> > +     struct rte_mbuf **ref_rx_pkts;
> >       uint16_t nb_pkts_received = 0;
> >       __m128i shuf_msk1, shuf_msk2, len_adjust;
> >
> > @@ -107,6 +108,7 @@ virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> >                       virtqueue_notify(vq);
> >       }
> >
> > +     ref_rx_pkts = rx_pkts;
> >       for (nb_pkts_received = 0;
> >               nb_pkts_received < nb_used;) {
> >               __m128i desc[RTE_VIRTIO_DESC_PER_LOOP / 2];
> > @@ -190,5 +192,9 @@ virtio_recv_pkts_vec(void *rx_queue, struct rte_mbuf **rx_pkts,
> >       vq->vq_used_cons_idx += nb_pkts_received;
> >       vq->vq_free_cnt += nb_pkts_received;
> >       rxvq->stats.packets += nb_pkts_received;
> > +     for (nb_used = 0; nb_used < nb_pkts_received; nb_used++) {
> > +             rxvq->stats.bytes += ref_rx_pkts[nb_used]->pkt_len;
> > +             virtio_update_packet_stats(&rxvq->stats, ref_rx_pkts[nb_used]);
>
> The stats.bytes was updated twice by above code.

Agree. My correction is an old one, done on the old 18.11 dpdk, and so
done before patch
https://git.dpdk.org/dpdk/commit/drivers/net/virtio/virtio_rxtx.c?id=81e5cdf19e583c742040d3be83b8cc79b451e243.
So the line
 +             rxvq->stats.bytes += ref_rx_pkts[nb_used]->pkt_len;
must be removed to be compliant with Ilya Maximets patch.

>
> > +     }
> >       return nb_pkts_received;
> >  }
> > --
> > 2.11.0
> >