Re: [PATCH net-next 4/5] virtio-net: support rx netdim

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On Wed, Nov 1, 2023 at 6:55 PM Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> wrote:
>
>
>
> 在 2023/10/25 上午11:34, Jason Wang 写道:
> > On Thu, Oct 12, 2023 at 3:44 PM Heng Qi <hengqi@xxxxxxxxxxxxxxxxx> wrote:
> >> By comparing the traffic information in the complete napi processes,
> >> let the virtio-net driver automatically adjust the coalescing
> >> moderation parameters of each receive queue.
> >>
> >> Signed-off-by: Heng Qi <hengqi@xxxxxxxxxxxxxxxxx>
> >> ---
> >>   drivers/net/virtio_net.c | 147 +++++++++++++++++++++++++++++++++------
> >>   1 file changed, 126 insertions(+), 21 deletions(-)
> >>
> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> >> index caef78bb3963..6ad2890a7909 100644
> >> --- a/drivers/net/virtio_net.c
> >> +++ b/drivers/net/virtio_net.c
> >> @@ -19,6 +19,7 @@
> >>   #include <linux/average.h>
> >>   #include <linux/filter.h>
> >>   #include <linux/kernel.h>
> >> +#include <linux/dim.h>
> >>   #include <net/route.h>
> >>   #include <net/xdp.h>
> >>   #include <net/net_failover.h>
> >> @@ -172,6 +173,17 @@ struct receive_queue {
> >>
> >>          struct virtnet_rq_stats stats;
> >>
> >> +       /* The number of rx notifications */
> >> +       u16 calls;
> >> +
> >> +       /* Is dynamic interrupt moderation enabled? */
> >> +       bool dim_enabled;
> >> +
> >> +       /* Dynamic Interrupt Moderation */
> >> +       struct dim dim;
> >> +
> >> +       u32 packets_in_napi;
> >> +
> >>          struct virtnet_interrupt_coalesce intr_coal;
> >>
> >>          /* Chain pages by the private ptr. */
> >> @@ -305,6 +317,9 @@ struct virtnet_info {
> >>          u8 duplex;
> >>          u32 speed;
> >>
> >> +       /* Is rx dynamic interrupt moderation enabled? */
> >> +       bool rx_dim_enabled;
> >> +
> >>          /* Interrupt coalescing settings */
> >>          struct virtnet_interrupt_coalesce intr_coal_tx;
> >>          struct virtnet_interrupt_coalesce intr_coal_rx;
> >> @@ -2001,6 +2016,7 @@ static void skb_recv_done(struct virtqueue *rvq)
> >>          struct virtnet_info *vi = rvq->vdev->priv;
> >>          struct receive_queue *rq = &vi->rq[vq2rxq(rvq)];
> >>
> >> +       rq->calls++;
> >>          virtqueue_napi_schedule(&rq->napi, rvq);
> >>   }
> >>
> >> @@ -2138,6 +2154,25 @@ static void virtnet_poll_cleantx(struct receive_queue *rq)
> >>          }
> >>   }
> >>
> >> +static void virtnet_rx_dim_work(struct work_struct *work);
> >> +
> >> +static void virtnet_rx_dim_update(struct virtnet_info *vi, struct receive_queue *rq)
> >> +{
> >> +       struct virtnet_rq_stats *stats = &rq->stats;
> >> +       struct dim_sample cur_sample = {};
> >> +
> >> +       if (!rq->packets_in_napi)
> >> +               return;
> >> +
> >> +       u64_stats_update_begin(&rq->stats.syncp);
> >> +       dim_update_sample(rq->calls, stats->packets,
> >> +                         stats->bytes, &cur_sample);
> >> +       u64_stats_update_end(&rq->stats.syncp);
> >> +
> >> +       net_dim(&rq->dim, cur_sample);
> >> +       rq->packets_in_napi = 0;
> >> +}
> >> +
> >>   static int virtnet_poll(struct napi_struct *napi, int budget)
> >>   {
> >>          struct receive_queue *rq =
> >> @@ -2146,17 +2181,22 @@ static int virtnet_poll(struct napi_struct *napi, int budget)
> >>          struct send_queue *sq;
> >>          unsigned int received;
> >>          unsigned int xdp_xmit = 0;
> >> +       bool napi_complete;
> >>
> >>          virtnet_poll_cleantx(rq);
> >>
> >>          received = virtnet_receive(rq, budget, &xdp_xmit);
> >> +       rq->packets_in_napi += received;
> >>
> >>          if (xdp_xmit & VIRTIO_XDP_REDIR)
> >>                  xdp_do_flush();
> >>
> >>          /* Out of packets? */
> >> -       if (received < budget)
> >> -               virtqueue_napi_complete(napi, rq->vq, received);
> >> +       if (received < budget) {
> >> +               napi_complete = virtqueue_napi_complete(napi, rq->vq, received);
> >> +               if (napi_complete && rq->dim_enabled)
> >> +                       virtnet_rx_dim_update(vi, rq);
> >> +       }
> >>
> >>          if (xdp_xmit & VIRTIO_XDP_TX) {
> >>                  sq = virtnet_xdp_get_sq(vi);
> >> @@ -2176,6 +2216,7 @@ static void virtnet_disable_queue_pair(struct virtnet_info *vi, int qp_index)
> >>          virtnet_napi_tx_disable(&vi->sq[qp_index].napi);
> >>          napi_disable(&vi->rq[qp_index].napi);
> >>          xdp_rxq_info_unreg(&vi->rq[qp_index].xdp_rxq);
> >> +       cancel_work_sync(&vi->rq[qp_index].dim.work);
> >>   }
> >>
> >>   static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
> >> @@ -2193,6 +2234,9 @@ static int virtnet_enable_queue_pair(struct virtnet_info *vi, int qp_index)
> >>          if (err < 0)
> >>                  goto err_xdp_reg_mem_model;
> >>
> >> +       INIT_WORK(&vi->rq[qp_index].dim.work, virtnet_rx_dim_work);
> >> +       vi->rq[qp_index].dim.mode = DIM_CQ_PERIOD_MODE_START_FROM_EQE;
> >> +
> >>          virtnet_napi_enable(vi->rq[qp_index].vq, &vi->rq[qp_index].napi);
> >>          virtnet_napi_tx_enable(vi, vi->sq[qp_index].vq, &vi->sq[qp_index].napi);
> >>
> >> @@ -3335,23 +3379,42 @@ static int virtnet_send_tx_notf_coal_cmds(struct virtnet_info *vi,
> >>   static int virtnet_send_rx_notf_coal_cmds(struct virtnet_info *vi,
> >>                                            struct ethtool_coalesce *ec)
> >>   {
> >> +       bool rx_ctrl_dim_on = !!ec->use_adaptive_rx_coalesce;
> >>          struct scatterlist sgs_rx;
> >> +       int i;
> >>
> >> -       vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
> >> -       vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
> >> -       sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));
> >> -
> >> -       if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
> >> -                                 VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
> >> -                                 &sgs_rx))
> >> +       if (rx_ctrl_dim_on && (ec->rx_coalesce_usecs != vi->intr_coal_rx.max_usecs ||
> >> +                              ec->rx_max_coalesced_frames != vi->intr_coal_rx.max_packets))
> > Any reason we need to stick a check for usecs/packets? I think it
> > might confuse the user since the value could be modified by netdim
> > actually.
>
> Yes, that's exactly what's done here.
>
> When dim is enabled, the user is prohibited from manually configuring
> parameters because dim may modify the parameters.

So it should be something like

if (rx_ctrl_dim_on)
      return -EINVAL;

without the checking of whether it matches the current parameters?

>
> >
> >>                  return -EINVAL;
> >>
> >> -       /* Save parameters */
> >> -       vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
> >> -       vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;
> >> -       for (i = 0; i < vi->max_queue_pairs; i++) {
> >> -               vi->rq[i].intr_coal.max_usecs = ec->rx_coalesce_usecs;
> >> -               vi->rq[i].intr_coal.max_packets = ec->rx_max_coalesced_frames;
> >> +       if (rx_ctrl_dim_on) {
> >> +               if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
> >> +                       vi->rx_dim_enabled = true;
> >> +                       for (i = 0; i < vi->max_queue_pairs; i++)
> >> +                               vi->rq[i].dim_enabled = true;
> >> +               } else {
> >> +                       return -EOPNOTSUPP;
> >> +               }
> >> +       } else {
> >> +               vi->rx_dim_enabled = false;
> >> +               for (i = 0; i < vi->max_queue_pairs; i++)
> >> +                       vi->rq[i].dim_enabled = false;
> >> +
> >> +               vi->ctrl->coal_rx.rx_usecs = cpu_to_le32(ec->rx_coalesce_usecs);
> >> +               vi->ctrl->coal_rx.rx_max_packets = cpu_to_le32(ec->rx_max_coalesced_frames);
> >> +               sg_init_one(&sgs_rx, &vi->ctrl->coal_rx, sizeof(vi->ctrl->coal_rx));
> >> +
> >> +               if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
> >> +                                         VIRTIO_NET_CTRL_NOTF_COAL_RX_SET,
> >> +                                         &sgs_rx))
> >> +                       return -EINVAL;
> >> +
> >> +               vi->intr_coal_rx.max_usecs = ec->rx_coalesce_usecs;
> >> +               vi->intr_coal_rx.max_packets = ec->rx_max_coalesced_frames;
> >> +               for (i = 0; i < vi->max_queue_pairs; i++) {
> >> +                       vi->rq[i].intr_coal.max_usecs = ec->rx_coalesce_usecs;
> >> +                       vi->rq[i].intr_coal.max_packets = ec->rx_max_coalesced_frames;
> >> +               }
> >>          }
> >>
> >>          return 0;
> >> @@ -3377,13 +3440,27 @@ static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
> >>                                            struct ethtool_coalesce *ec,
> >>                                            u16 queue)
> >>   {
> >> +       bool rx_ctrl_dim_on;
> >> +       u32 max_usecs, max_packets;
> >>          int err;
> >>
> >> -       err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, queue,
> >> -                                              ec->rx_coalesce_usecs,
> >> -                                              ec->rx_max_coalesced_frames);
> >> -       if (err)
> >> -               return err;
> >> +       rx_ctrl_dim_on = !!ec->use_adaptive_rx_coalesce;
> >> +       max_usecs = vi->rq[queue].intr_coal.max_usecs;
> >> +       max_packets = vi->rq[queue].intr_coal.max_packets;
> >> +       if (rx_ctrl_dim_on && (ec->rx_coalesce_usecs != max_usecs ||
> >> +                              ec->rx_max_coalesced_frames != max_packets))
> >> +               return -EINVAL;
> >> +
> >> +       if (rx_ctrl_dim_on) {
> >> +               vi->rq[queue].dim_enabled = true;
> >> +       } else {
> >> +               vi->rq[queue].dim_enabled = false;
> >> +               err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, queue,
> >> +                                                      ec->rx_coalesce_usecs,
> >> +                                                      ec->rx_max_coalesced_frames);
> >> +               if (err)
> >> +                       return err;
> >> +       }
> >>
> >>          err = virtnet_send_tx_ctrl_coal_vq_cmd(vi, queue,
> >>                                                 ec->tx_coalesce_usecs,
> >> @@ -3394,6 +3471,32 @@ static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
> >>          return 0;
> >>   }
> >>
> >> +static void virtnet_rx_dim_work(struct work_struct *work)
> >> +{
> >> +       struct dim *dim = container_of(work, struct dim, work);
> >> +       struct receive_queue *rq = container_of(dim,
> >> +                       struct receive_queue, dim);
> >> +       struct virtnet_info *vi = rq->vq->vdev->priv;
> >> +       struct net_device *dev = vi->dev;
> >> +       struct dim_cq_moder update_moder;
> >> +       int qnum = rq - vi->rq, err;
> >> +
> >> +       update_moder = net_dim_get_rx_moderation(dim->mode, dim->profile_ix);
> >> +       if (update_moder.usec != vi->rq[qnum].intr_coal.max_usecs ||
> >> +           update_moder.pkts != vi->rq[qnum].intr_coal.max_packets) {
> > Is this safe across the e.g vq reset?
>
> I think it might. This will be avoided in the next version using:
> 1. cancel virtnet_rx_dim_work before vq reset.
> 2. restore virtnet_rx_dim_work after vq re-enable.

Ok.

Thanks

>
> Thanks a lot!
>
> >
> > Thanks
> >
> >> +               rtnl_lock();
> >> +               err = virtnet_send_rx_ctrl_coal_vq_cmd(vi, qnum,
> >> +                                                      update_moder.usec,
> >> +                                                      update_moder.pkts);
> >> +               if (err)
> >> +                       pr_debug("%s: Failed to send dim parameters on rxq%d\n",
> >> +                                dev->name, (int)(rq - vi->rq));
> >> +               rtnl_unlock();
> >> +       }
> >> +
> >> +       dim->state = DIM_START_MEASURE;
> >> +}
> >> +
> >>   static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
> >>   {
> >>          /* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
> >> @@ -3475,6 +3578,7 @@ static int virtnet_get_coalesce(struct net_device *dev,
> >>                  ec->tx_coalesce_usecs = vi->intr_coal_tx.max_usecs;
> >>                  ec->tx_max_coalesced_frames = vi->intr_coal_tx.max_packets;
> >>                  ec->rx_max_coalesced_frames = vi->intr_coal_rx.max_packets;
> >> +               ec->use_adaptive_rx_coalesce = vi->rx_dim_enabled;
> >>          } else {
> >>                  ec->rx_max_coalesced_frames = 1;
> >>
> >> @@ -3532,6 +3636,7 @@ static int virtnet_get_per_queue_coalesce(struct net_device *dev,
> >>                  ec->tx_coalesce_usecs = vi->sq[queue].intr_coal.max_usecs;
> >>                  ec->tx_max_coalesced_frames = vi->sq[queue].intr_coal.max_packets;
> >>                  ec->rx_max_coalesced_frames = vi->rq[queue].intr_coal.max_packets;
> >> +               ec->use_adaptive_rx_coalesce = vi->rq[queue].dim_enabled;
> >>          } else {
> >>                  ec->rx_max_coalesced_frames = 1;
> >>
> >> @@ -3657,7 +3762,7 @@ static int virtnet_set_rxnfc(struct net_device *dev, struct ethtool_rxnfc *info)
> >>
> >>   static const struct ethtool_ops virtnet_ethtool_ops = {
> >>          .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
> >> -               ETHTOOL_COALESCE_USECS,
> >> +               ETHTOOL_COALESCE_USECS | ETHTOOL_COALESCE_USE_ADAPTIVE_RX,
> >>          .get_drvinfo = virtnet_get_drvinfo,
> >>          .get_link = ethtool_op_get_link,
> >>          .get_ringparam = virtnet_get_ringparam,
> >> --
> >> 2.19.1.6.gb485710b
> >>
>

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