On Tue, 7 May 2024 14:24:12 +0800, Jason Wang <jasow...@redhat.com> wrote:
> On Fri, Apr 26, 2024 at 2:54 PM Heng Qi <hen...@linux.alibaba.com> wrote:
> >
> > Currently, virtio-net lacks a way to obtain the default coalesce
> > values of the device during the probe phase. That is, the device
> > may have default experience values, but the user uses "ethtool -c"
> > to query that the values are still 0.
> >
> > Therefore, we reuse VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET to complete the goal.
> >
> > Signed-off-by: Heng Qi <hen...@linux.alibaba.com>
> > ---
> > drivers/net/virtio_net.c | 68 +++++++++++++++++++++++++++++++++++-----
> > 1 file changed, 61 insertions(+), 7 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 3bc9b1e621db..fe0c15819dd3 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -4623,6 +4623,46 @@ static int virtnet_validate(struct virtio_device
> > *vdev)
> > return 0;
> > }
> >
> > +static int virtnet_get_coal_init_value(struct virtnet_info *vi,
> > + u16 _vqn, bool is_tx)
> > +{
> > + struct virtio_net_ctrl_coal *coal = &vi->ctrl->coal_vq.coal;
> > + __le16 *vqn = &vi->ctrl->coal_vq.vqn;
> > + struct scatterlist sgs_in, sgs_out;
> > + u32 usecs, pkts, i;
> > + bool ret;
> > +
> > + *vqn = cpu_to_le16(_vqn);
> > +
> > + sg_init_one(&sgs_out, vqn, sizeof(*vqn));
> > + sg_init_one(&sgs_in, coal, sizeof(*coal));
> > + ret = virtnet_send_command_reply(vi, VIRTIO_NET_CTRL_NOTF_COAL,
> > + VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET,
> > + &sgs_out, &sgs_in);
> > + if (!ret)
> > + return ret;
> > +
> > + usecs = le32_to_cpu(coal->max_usecs);
> > + pkts = le32_to_cpu(coal->max_packets);
> > + if (is_tx) {
> > + vi->intr_coal_tx.max_usecs = usecs;
> > + vi->intr_coal_tx.max_packets = pkts;
> > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > + vi->sq[i].intr_coal.max_usecs = usecs;
> > + vi->sq[i].intr_coal.max_packets = pkts;
> > + }
> > + } else {
> > + vi->intr_coal_rx.max_usecs = usecs;
> > + vi->intr_coal_rx.max_packets = pkts;
> > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > + vi->rq[i].intr_coal.max_usecs = usecs;
> > + vi->rq[i].intr_coal.max_packets = pkts;
> > + }
> > + }
> > +
> > + return 0;
> > +}
> > +
> > static bool virtnet_check_guest_gso(const struct virtnet_info *vi)
> > {
> > return virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
> > @@ -4885,13 +4925,6 @@ static int virtnet_probe(struct virtio_device *vdev)
> > vi->intr_coal_tx.max_packets = 0;
> > }
> >
> > - if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
> > - /* The reason is the same as VIRTIO_NET_F_NOTF_COAL. */
> > - for (i = 0; i < vi->max_queue_pairs; i++)
> > - if (vi->sq[i].napi.weight)
> > - vi->sq[i].intr_coal.max_packets = 1;
> > - }
> > -
> > #ifdef CONFIG_SYSFS
> > if (vi->mergeable_rx_bufs)
> > dev->sysfs_rx_queue_group = &virtio_net_mrg_rx_group;
> > @@ -4926,6 +4959,27 @@ static int virtnet_probe(struct virtio_device *vdev)
> >
> > virtio_device_ready(vdev);
> >
> > + if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
> > + /* The reason is the same as VIRTIO_NET_F_NOTF_COAL. */
> > + for (i = 0; i < vi->max_queue_pairs; i++)
> > + if (vi->sq[i].napi.weight)
> > + vi->sq[i].intr_coal.max_packets = 1;
> > +
> > + /* The loop exits if the default value from any
> > + * queue is successfully read.
> > + */
>
> So this assumes the default values are the same. Is this something
> required by the spec? If not, we probably need to iterate all the
> queues.
>
>From internal practice, and from the default behavior of other existing
>drivers,
the queues all have the same value at the beginning, so here it seems feasible
that we get the value of queue 0 to represent the global value instead of using
a loop.
Moreover, obtaining the value once for each queue initially does not seem to be
very friendly for devices with a large number of queues.
Thanks.
> Thanks
>
>
> > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > + err = virtnet_get_coal_init_value(vi, rxq2vq(i),
> > false);
> > + if (!err)
> > + break;
> > + }
> > + for (i = 0; i < vi->max_queue_pairs; i++) {
> > + err = virtnet_get_coal_init_value(vi, txq2vq(i),
> > true);
> > + if (!err)
> > + break;
> > + }
> > + }
> > +
> > _virtnet_set_queues(vi, vi->curr_queue_pairs);
> >
> > /* a random MAC address has been assigned, notify the device.
> > --
> > 2.32.0.3.g01195cf9f
> >
>
