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Date: Thu, 2 Nov 2023 12:31:48 +0800
From: Jason Wang <jasowang@...hat.com>
To: Heng Qi <hengqi@...ux.alibaba.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
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?
>
> >
> >> 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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