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Message-ID: <3efcaee7-7e33-4513-b9d0-76ed92f8b1a4@linux.alibaba.com>
Date: Thu, 2 Nov 2023 12:46:59 +0800
From: Heng Qi <hengqi@...ux.alibaba.com>
To: Jason Wang <jasowang@...hat.com>
Cc: "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
 virtualization@...ts.linux-foundation.org,
 Xuan Zhuo <xuanzhuo@...ux.alibaba.com>, Eric Dumazet <edumazet@...gle.com>,
 "David S. Miller" <davem@...emloft.net>, Paolo Abeni <pabeni@...hat.com>,
 Jesper Dangaard Brouer <hawk@...nel.org>,
 John Fastabend <john.fastabend@...il.com>,
 Alexei Starovoitov <ast@...nel.org>, Jakub Kicinski <kuba@...nel.org>,
 Simon Horman <horms@...nel.org>, "Liu, Yujie" <yujie.liu@...el.com>
Subject: Re: [PATCH net-next 4/5] virtio-net: support rx netdim



在 2023/11/2 下午12:31, Jason Wang 写道:
> On Wed, Nov 1, 2023 at 6:55 PM Heng Qi <hengqi@...ux.alibaba.com> 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@...ux.alibaba.com> 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@...ux.alibaba.com>
>>>> ---
>>>>    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?

I think yes.

Thanks!

>
>>>>                   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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