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Tsirkin" To: Alvaro Karsz Cc: netdev@vger.kernel.org, rabeeh@solid-run.com, Jason Wang , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Subject: Re: [PATCH] net: virtio_net: support interrupt coalescing Message-ID: <20220512055039-mutt-send-email-mst@kernel.org> References: <20220512083523.1954281-1-alvaro.karsz@solid-run.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220512083523.1954281-1-alvaro.karsz@solid-run.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 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