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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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