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Message-ID: <20230724032451-mutt-send-email-mst@kernel.org>
Date: Mon, 24 Jul 2023 03:32:50 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Gavin Li <gavinl@...dia.com>
Cc: jasowang@...hat.com, xuanzhuo@...ux.alibaba.com, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
ast@...nel.org, daniel@...earbox.net, hawk@...nel.org,
john.fastabend@...il.com, jiri@...dia.com, dtatulea@...dia.com,
gavi@...dia.com, virtualization@...ts.linux-foundation.org,
netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: Re: [PATCH net-next V3 3/4] virtio_net: support per queue interrupt
coalesce command
On Mon, Jul 24, 2023 at 06:40:47AM +0300, Gavin Li wrote:
> Add interrupt_coalesce config in send_queue and receive_queue to cache user
> config.
>
> Send per virtqueue interrupt moderation config to underline device in order
> to have more efficient interrupt moderation and cpu utilization of guest
> VM.
>
> Signed-off-by: Gavin Li <gavinl@...dia.com>
> Reviewed-by: Dragos Tatulea <dtatulea@...dia.com>
> Reviewed-by: Jiri Pirko <jiri@...dia.com>
> Acked-by: Michael S. Tsirkin <mst@...hat.com>
> ---
> drivers/net/virtio_net.c | 120 ++++++++++++++++++++++++++++----
> include/uapi/linux/virtio_net.h | 14 ++++
> 2 files changed, 122 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 802ed21453f5..0c3ee1e26ece 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -144,6 +144,8 @@ struct send_queue {
>
> struct virtnet_sq_stats stats;
>
> + struct virtnet_interrupt_coalesce intr_coal;
> +
> struct napi_struct napi;
>
> /* Record whether sq is in reset state. */
> @@ -161,6 +163,8 @@ struct receive_queue {
>
> struct virtnet_rq_stats stats;
>
> + struct virtnet_interrupt_coalesce intr_coal;
> +
> /* Chain pages by the private ptr. */
> struct page *pages;
>
> @@ -212,6 +216,7 @@ struct control_buf {
> struct virtio_net_ctrl_rss rss;
> struct virtio_net_ctrl_coal_tx coal_tx;
> struct virtio_net_ctrl_coal_rx coal_rx;
> + struct virtio_net_ctrl_coal_vq coal_vq;
> };
>
> struct virtnet_info {
> @@ -3078,6 +3083,55 @@ static int virtnet_send_notf_coal_cmds(struct virtnet_info *vi,
> return 0;
> }
>
> +static int virtnet_send_ctrl_coal_vq_cmd(struct virtnet_info *vi,
> + u16 vqn, u32 max_usecs, u32 max_packets)
> +{
> + struct scatterlist sgs;
> +
> + vi->ctrl->coal_vq.vqn = cpu_to_le16(vqn);
> + vi->ctrl->coal_vq.coal.max_usecs = cpu_to_le32(max_usecs);
> + vi->ctrl->coal_vq.coal.max_packets = cpu_to_le32(max_packets);
> + sg_init_one(&sgs, &vi->ctrl->coal_vq, sizeof(vi->ctrl->coal_vq));
> +
> + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_NOTF_COAL,
> + VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET,
> + &sgs))
> + return -EINVAL;
> +
> + return 0;
> +}
> +
> +static int virtnet_send_notf_coal_vq_cmds(struct virtnet_info *vi,
> + struct ethtool_coalesce *ec,
> + u16 queue)
> +{
> + int err;
> +
> + if (ec->rx_coalesce_usecs || ec->rx_max_coalesced_frames) {
> + err = virtnet_send_ctrl_coal_vq_cmd(vi, rxq2vq(queue),
> + ec->rx_coalesce_usecs,
> + ec->rx_max_coalesced_frames);
> + if (err)
> + return err;
> + /* Save parameters */
> + vi->rq[queue].intr_coal.max_usecs = ec->rx_coalesce_usecs;
> + vi->rq[queue].intr_coal.max_packets = ec->rx_max_coalesced_frames;
> + }
> +
> + if (ec->tx_coalesce_usecs || ec->tx_max_coalesced_frames) {
> + err = virtnet_send_ctrl_coal_vq_cmd(vi, txq2vq(queue),
> + ec->tx_coalesce_usecs,
> + ec->tx_max_coalesced_frames);
> + if (err)
> + return err;
> + /* Save parameters */
> + vi->sq[queue].intr_coal.max_usecs = ec->tx_coalesce_usecs;
> + vi->sq[queue].intr_coal.max_packets = ec->tx_max_coalesced_frames;
> + }
> +
> + return 0;
> +}
> +
> static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
> {
> /* usecs coalescing is supported only if VIRTIO_NET_F_NOTF_COAL
> @@ -3094,23 +3148,39 @@ static int virtnet_coal_params_supported(struct ethtool_coalesce *ec)
> }
>
> static int virtnet_set_coalesce_one(struct net_device *dev,
> - struct ethtool_coalesce *ec)
> + struct ethtool_coalesce *ec,
> + bool per_queue,
> + u32 queue)
> {
> struct virtnet_info *vi = netdev_priv(dev);
> - int ret, i, napi_weight;
> + int queue_count = per_queue ? 1 : vi->max_queue_pairs;
> + int queue_number = per_queue ? queue : 0;
Actually can't we refactor this? This whole function is littered
with if/else branches. just code it separately - the only
common part is:
napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
if (napi_weight ^ vi->sq[0].napi.weight) {
if (dev->flags & IFF_UP)
return -EBUSY;
else
update_napi = true;
}
so just move this to a helper and have two functions - global and
per queue.
> bool update_napi = false;
> + int ret, i, napi_weight;
> +
> + if (queue >= vi->max_queue_pairs)
> + return -EINVAL;
>
> /* Can't change NAPI weight if the link is up */
> napi_weight = ec->tx_max_coalesced_frames ? NAPI_POLL_WEIGHT : 0;
> - if (napi_weight ^ vi->sq[0].napi.weight) {
> - if (dev->flags & IFF_UP)
> - return -EBUSY;
> - else
> + for (i = queue_number; i < queue_count; i++) {
> + if (napi_weight ^ vi->sq[i].napi.weight) {
> + if (dev->flags & IFF_UP)
> + return -EBUSY;
> +
> update_napi = true;
> + /* All queues that belong to [queue_number, queue_count] will be
> + * updated for the sake of simplicity, which might not be necessary
> + */
> + queue_number = i;
> + break;
> + }
> }
>
> - if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
> + if (!per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL))
> ret = virtnet_send_notf_coal_cmds(vi, ec);
> + else if (per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL))
> + ret = virtnet_send_notf_coal_vq_cmds(vi, ec, queue);
> else
> ret = virtnet_coal_params_supported(ec);
>
> @@ -3118,7 +3188,7 @@ static int virtnet_set_coalesce_one(struct net_device *dev,
> return ret;
>
> if (update_napi) {
> - for (i = 0; i < vi->max_queue_pairs; i++)
> + for (i = queue_number; i < queue_count; i++)
> vi->sq[i].napi.weight = napi_weight;
> }
>
> @@ -3130,19 +3200,29 @@ static int virtnet_set_coalesce(struct net_device *dev,
> struct kernel_ethtool_coalesce *kernel_coal,
> struct netlink_ext_ack *extack)
> {
> - return virtnet_set_coalesce_one(dev, ec);
> + return virtnet_set_coalesce_one(dev, ec, false, 0);
> }
>
> static int virtnet_get_coalesce_one(struct net_device *dev,
> - struct ethtool_coalesce *ec)
> + struct ethtool_coalesce *ec,
> + bool per_queue,
> + u32 queue)
> {
> struct virtnet_info *vi = netdev_priv(dev);
>
> - if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
> + if (queue >= vi->max_queue_pairs)
> + return -EINVAL;
> +
> + if (!per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
> ec->rx_coalesce_usecs = vi->intr_coal_rx.max_usecs;
> 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;
> + } else if (per_queue && virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
> + ec->rx_coalesce_usecs = vi->rq[queue].intr_coal.max_usecs;
> + 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;
> } else {
> ec->rx_max_coalesced_frames = 1;
>
> @@ -3158,7 +3238,21 @@ static int virtnet_get_coalesce(struct net_device *dev,
> struct kernel_ethtool_coalesce *kernel_coal,
> struct netlink_ext_ack *extack)
> {
> - return virtnet_get_coalesce_one(dev, ec);
> + return virtnet_get_coalesce_one(dev, ec, false, 0);
> +}
> +
> +static int virtnet_set_per_queue_coalesce(struct net_device *dev,
> + u32 queue,
> + struct ethtool_coalesce *ec)
> +{
> + return virtnet_set_coalesce_one(dev, ec, true, queue);
> +}
> +
> +static int virtnet_get_per_queue_coalesce(struct net_device *dev,
> + u32 queue,
> + struct ethtool_coalesce *ec)
> +{
> + return virtnet_get_coalesce_one(dev, ec, true, queue);
> }
>
> static void virtnet_init_settings(struct net_device *dev)
> @@ -3291,6 +3385,8 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
> .set_link_ksettings = virtnet_set_link_ksettings,
> .set_coalesce = virtnet_set_coalesce,
> .get_coalesce = virtnet_get_coalesce,
> + .set_per_queue_coalesce = virtnet_set_per_queue_coalesce,
> + .get_per_queue_coalesce = virtnet_get_per_queue_coalesce,
> .get_rxfh_key_size = virtnet_get_rxfh_key_size,
> .get_rxfh_indir_size = virtnet_get_rxfh_indir_size,
> .get_rxfh = virtnet_get_rxfh,
> diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
> index 12c1c9699935..cc65ef0f3c3e 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -56,6 +56,7 @@
> #define VIRTIO_NET_F_MQ 22 /* Device supports Receive Flow
> * Steering */
> #define VIRTIO_NET_F_CTRL_MAC_ADDR 23 /* Set MAC address */
> +#define VIRTIO_NET_F_VQ_NOTF_COAL 52 /* Device supports virtqueue notification coalescing */
> #define VIRTIO_NET_F_NOTF_COAL 53 /* Device supports notifications coalescing */
> #define VIRTIO_NET_F_GUEST_USO4 54 /* Guest can handle USOv4 in. */
> #define VIRTIO_NET_F_GUEST_USO6 55 /* Guest can handle USOv6 in. */
> @@ -391,5 +392,18 @@ struct virtio_net_ctrl_coal_rx {
> };
>
> #define VIRTIO_NET_CTRL_NOTF_COAL_RX_SET 1
> +#define VIRTIO_NET_CTRL_NOTF_COAL_VQ_SET 2
> +#define VIRTIO_NET_CTRL_NOTF_COAL_VQ_GET 3
> +
> +struct virtio_net_ctrl_coal {
> + __le32 max_packets;
> + __le32 max_usecs;
> +};
> +
> +struct virtio_net_ctrl_coal_vq {
> + __le16 vqn;
> + __le16 reserved;
> + struct virtio_net_ctrl_coal coal;
> +};
>
> #endif /* _UAPI_LINUX_VIRTIO_NET_H */
> --
> 2.39.1
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