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Date: Thu, 12 May 2022 09:41:44 -0400
From: "Michael S. Tsirkin" <mst@...hat.com>
To: Alvaro Karsz <alvaro.karsz@...id-run.com>
Cc: netdev@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Rabeeh Khoury <rabeeh@...id-run.com>
Subject: Re: [PATCH] net: virtio_net: support interrupt coalescing
On Thu, May 12, 2022 at 03:54:28PM +0300, Alvaro Karsz wrote:
> So first, please at least reserve the feature in the virtio spec.
> Preferably add the specification as well.
> Here's one way to do it:
> https://github.com/oasis-tcs/virtio-spec#use-of-github-issues
>
>
> Sorry about that.
> I sent a patch to the virtio comment list, but thought that I should wait
> until I got a few comments before opening a github issue.
> https://lists.oasis-open.org/archives/virtio-comment/202205/msg00016.html
> Should I open the github issue now? or should I wait a little for more comments
> on the virtio-spec patch?
At this point you can wait.
>
> You want all these to be LE. Native endian's unpredictable in lots of
> virt settings.
>
>
> I will fix this, wait a few more days to see if there are more comments, and
> then create a new version of the patch.
>
> Thanks
>
> On Thu, May 12, 2022 at 12:55 PM Michael S. Tsirkin <mst@...hat.com> wrote:
>
> On Thu, May 12, 2022 at 11:35:23AM +0300, Alvaro Karsz wrote:
> > Control a Virtio network device interrupt coalescing parameters
> > using the control virtqueue.
> >
> > New VirtIO network feature: VIRTIO_NET_F_INTR_COAL.
> >
> > A device that supports this fetature can receive
> > VIRTIO_NET_CTRL_INTR_COAL control commands.
> >
> > * VIRTIO_NET_CTRL_INTR_COAL_USECS_SET:
> > change the rx-usecs and tx-usecs parameters.
> >
> > rx-usecs - Time to delay an RX interrupt after packet arrival in
> > microseconds.
> >
> > tx-usecs - Time to delay a TX interrupt after a sending a packet
> > in microseconds.
> >
> > * VIRTIO_NET_CTRL_INTR_COAL_FRAMES_SET:
> > change the rx-max-frames and tx-max-frames parameters.
> >
> > rx-max-frames: Number of packets to delay an RX interrupt after
> > packet arrival.
> >
> > tx-max-frames: Number of packets to delay a TX interrupt after
> > sending a packet.
> >
> > Signed-off-by: Alvaro Karsz <alvaro.karsz@...id-run.com>
>
> So first, please at least reserve the feature in the virtio spec.
> Preferably add the specification as well.
> Here's one way to do it:
> https://github.com/oasis-tcs/virtio-spec#use-of-github-issues
>
>
> > ---
> > drivers/net/virtio_net.c | 108 ++++++++++++++++++++++++++++----
> > include/uapi/linux/virtio_net.h | 34 +++++++++-
> > 2 files changed, 128 insertions(+), 14 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index cbba9d2e8f3..4806c35ddd5 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -261,6 +261,12 @@ struct virtnet_info {
> > u8 duplex;
> > u32 speed;
> >
> > + /* Interrupt coalescing settings */
> > + u32 tx_usecs;
> > + u32 rx_usecs;
> > + u32 tx_frames_max;
> > + u32 rx_frames_max;
> > +
> > unsigned long guest_offloads;
> > unsigned long guest_offloads_capable;
> >
> > @@ -2594,19 +2600,75 @@ static int virtnet_set_coalesce(struct net_device
> *dev,
> > {
> > struct virtnet_info *vi = netdev_priv(dev);
> > int i, napi_weight;
> > + struct scatterlist sgs_usecs, sgs_frames;
> > + struct virtio_net_ctrl_coal_frames c_frames;
> > + struct virtio_net_ctrl_coal_usec c_usecs;
> > + bool update_napi,
> > + intr_coal = virtio_has_feature(vi->vdev, VIRTIO_NET_F_INTR_COAL);
> > +
> > + /* rx_coalesce_usecs/tx_coalesce_usecs are supported only
> > + * if VIRTIO_NET_F_INTR_COAL feature is set.
> > + */
> > + if (!intr_coal && (ec->rx_coalesce_usecs || ec->tx_coalesce_usecs))
> > + return -EOPNOTSUPP;
> > +
> > + if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_INTR_COAL)) {
> > + /* Send usec command */
> > + c_usecs.tx_usecs = ec->tx_coalesce_usecs;
> > + c_usecs.rx_usecs = ec->rx_coalesce_usecs;
> > + sg_init_one(&sgs_usecs, &c_usecs, sizeof(c_usecs));
> > +
> > + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_INTR_COAL,
> > +
> VIRTIO_NET_CTRL_INTR_COAL_USECS_SET,
> > + &sgs_usecs))
> > + return -EINVAL;
> > +
> > + /* Save parameters */
> > + vi->tx_usecs = ec->tx_coalesce_usecs;
> > + vi->rx_usecs = ec->rx_coalesce_usecs;
> > +
> > + /* Send frames command */
> > + c_frames.tx_frames_max = ec->tx_max_coalesced_frames;
> > + c_frames.rx_frames_max = ec->rx_max_coalesced_frames;
> > + sg_init_one(&sgs_frames, &c_frames, sizeof(c_frames));
> > +
> > + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_INTR_COAL,
> > +
> VIRTIO_NET_CTRL_INTR_COAL_FRAMES_SET,
> > + &sgs_frames))
> > + return -EINVAL;
> > +
> > + /* Save parameters */
> > + vi->tx_frames_max = ec->tx_max_coalesced_frames;
> > + vi->rx_frames_max = ec->rx_max_coalesced_frames;
>
>
>
>
> > + }
> > +
> > + /* Should we update NAPI? */
> > + update_napi = ec->tx_max_coalesced_frames <= 1 &&
> > + ec->rx_max_coalesced_frames == 1;
> >
> > - if (ec->tx_max_coalesced_frames > 1 ||
> > - ec->rx_max_coalesced_frames != 1)
> > + /* If interrupt coalesing feature is not set, and we can't update
> NAPI, return an error */
> > + if (!intr_coal && !update_napi)
> > return -EINVAL;
> >
> > - 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;
> > - for (i = 0; i < vi->max_queue_pairs; i++)
> > - vi->sq[i].napi.weight = napi_weight;
> > + if (update_napi) {
> > + napi_weight = ec->tx_max_coalesced_frames ?
> NAPI_POLL_WEIGHT : 0;
> > + if (napi_weight ^ vi->sq[0].napi.weight) {
> > + if (dev->flags & IFF_UP) {
> > + /* If Interrupt coalescing feature is not
> set, return an error.
> > + * Otherwise exit without changing the NAPI
> paremeters
> > + */
> > + if (!intr_coal)
> > + return -EBUSY;
> > +
> > + goto exit;
> > + }
> > +
> > + for (i = 0; i < vi->max_queue_pairs; i++)
> > + vi->sq[i].napi.weight = napi_weight;
> > + }
> > }
> >
> > +exit:
> > return 0;
> > }
> >
> > @@ -2616,14 +2678,25 @@ static int virtnet_get_coalesce(struct net_device
> *dev,
> > struct netlink_ext_ack *extack)
> > {
> > struct ethtool_coalesce ec_default = {
> > - .cmd = ETHTOOL_GCOALESCE,
> > - .rx_max_coalesced_frames = 1,
> > + .cmd = ETHTOOL_GCOALESCE
> > };
> > +
> > struct virtnet_info *vi = netdev_priv(dev);
> > + bool intr_coal = virtio_has_feature(vi->vdev,
> VIRTIO_NET_F_INTR_COAL);
> > +
> > + /* Add Interrupt coalescing settings */
> > + if (intr_coal) {
> > + ec_default.rx_coalesce_usecs = vi->rx_usecs;
> > + ec_default.tx_coalesce_usecs = vi->tx_usecs;
> > + ec_default.tx_max_coalesced_frames = vi->tx_frames_max;
> > + ec_default.rx_max_coalesced_frames = vi->rx_frames_max;
> > + } else {
> > + ec_default.rx_max_coalesced_frames = 1;
> > + }
> >
> > memcpy(ec, &ec_default, sizeof(ec_default));
> >
> > - if (vi->sq[0].napi.weight)
> > + if (!intr_coal && vi->sq[0].napi.weight)
> > ec->tx_max_coalesced_frames = 1;
> >
> > return 0;
> > @@ -2743,7 +2816,7 @@ 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,
> > + .supported_coalesce_params = ETHTOOL_COALESCE_MAX_FRAMES |
> ETHTOOL_COALESCE_USECS,
> > .get_drvinfo = virtnet_get_drvinfo,
> > .get_link = ethtool_op_get_link,
> > .get_ringparam = virtnet_get_ringparam,
> > @@ -3423,6 +3496,8 @@ static bool virtnet_validate_features(struct
> virtio_device *vdev)
> > VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_RSS,
> > "VIRTIO_NET_F_CTRL_VQ") ||
> > VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_HASH_REPORT,
> > + "VIRTIO_NET_F_CTRL_VQ") ||
> > + VIRTNET_FAIL_ON(vdev, VIRTIO_NET_F_INTR_COAL,
> > "VIRTIO_NET_F_CTRL_VQ"))) {
> > return false;
> > }
> > @@ -3558,6 +3633,13 @@ static int virtnet_probe(struct virtio_device
> *vdev)
> > if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF))
> > vi->mergeable_rx_bufs = true;
> >
> > + if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_INTR_COAL)) {
> > + vi->rx_usecs = 0;
> > + vi->tx_usecs = 0;
> > + vi->tx_frames_max = 0;
> > + vi->rx_frames_max = 0;
> > + }
> > +
> > if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
> > vi->has_rss_hash_report = true;
> >
> > @@ -3786,7 +3868,7 @@ static struct virtio_device_id id_table[] = {
> > VIRTIO_NET_F_CTRL_MAC_ADDR, \
> > VIRTIO_NET_F_MTU, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, \
> > VIRTIO_NET_F_SPEED_DUPLEX, VIRTIO_NET_F_STANDBY, \
> > - VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT
> > + VIRTIO_NET_F_RSS, VIRTIO_NET_F_HASH_REPORT, VIRTIO_NET_F_INTR_COAL
> >
> > static unsigned int features[] = {
> > VIRTNET_FEATURES,
> > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/
> virtio_net.h
> > index 3f55a4215f1..b65a4295270 100644
> > --- a/include/uapi/linux/virtio_net.h
> > +++ b/include/uapi/linux/virtio_net.h
> > @@ -56,7 +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_INTR_COAL 55 /* Guest can handle
> Interrupt coalescing */
> > #define VIRTIO_NET_F_HASH_REPORT 57 /* Supports hash report */
> > #define VIRTIO_NET_F_RSS 60 /* Supports RSS RX steering */
> > #define VIRTIO_NET_F_RSC_EXT 61 /* extended coalescing info */
> > @@ -355,4 +355,36 @@ struct virtio_net_hash_config {
> > #define VIRTIO_NET_CTRL_GUEST_OFFLOADS 5
> > #define VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET 0
> >
> > +/*
> > + * Control interrupt coalescing.
> > + *
> > + * Request the device to change the interrupt coalescing parameters.
> > + *
> > + * Available with the VIRTIO_NET_F_INTR_COAL feature bit.
> > + */
> > +#define VIRTIO_NET_CTRL_INTR_COAL 6
> > +/*
> > + * Set the rx-usecs/tx-usecs patameters.
> > + * rx-usecs - Number of microseconds to delay an RX interrupt after
> packet arrival.
> > + * tx-usecs - Number of microseconds to delay a TX interrupt after a
> sending a packet.
> > + */
> > +struct virtio_net_ctrl_coal_usec {
> > + __u32 tx_usecs;
> > + __u32 rx_usecs;
> > +};
> > +
> > +#define VIRTIO_NET_CTRL_INTR_COAL_USECS_SET 0
> > +
> > +/*
> > + * Set the rx-max-frames/tx-max-frames patameters.
> > + * rx-max-frames - Number of packets to delay an RX interrupt after
> packet arrival.
> > + * tx-max-frames - Number of packets to delay a TX interrupt after
> sending a packet.
> > + */
> > +struct virtio_net_ctrl_coal_frames {
> > + __u32 tx_frames_max;
> > + __u32 rx_frames_max;
> > +};
> > +
>
> You want all these to be LE. Native endian's unpredictable in lots of
> virt settings.
>
>
> > +#define VIRTIO_NET_CTRL_INTR_COAL_FRAMES_SET 1
> > +
> > #endif /* _UAPI_LINUX_VIRTIO_NET_H */
> > --
> > 2.32.0
>
>
>
>
> --
> [uc]
>
> Alvaro Karsz, Software
> +972-50-7696862| https://www.solid-run.com
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