From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH RFC v5 net-next 4/6] virtio-net: add basic interrupt coalescing support Date: Tue, 10 Feb 2015 11:40:19 +0100 Message-ID: <20150210104019.GD9505@redhat.com> References: <1423471165-34243-1-git-send-email-jasowang@redhat.com> <1423471165-34243-5-git-send-email-jasowang@redhat.com> <87386ey2iy.fsf@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: pagupta@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org To: Rusty Russell Return-path: Content-Disposition: inline In-Reply-To: <87386ey2iy.fsf@rustcorp.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On Tue, Feb 10, 2015 at 12:02:37PM +1030, Rusty Russell wrote: > Jason Wang writes: > > This patch enables the interrupt coalescing setting through ethtool. > > The problem is that there's nothing network specific about interrupt > coalescing. I can see other devices wanting exactly the same thing, > which means we'd deprecate this in the next virtio standard. > > I think the right answer is to extend like we did with > vring_used_event(), eg: > > 1) Add a new feature VIRTIO_F_RING_COALESCE. > 2) Add another a 32-bit field after vring_used_event(), eg: > #define vring_used_delay(vr) (*(u32 *)((vr)->avail->ring[(vr)->num + 2])) > > This loses the ability to coalesce by number of frames, but we can still > do number of sg entries, as we do now with used_event, and we could > change virtqueue_enable_cb_delayed() to take a precise number if we > wanted. But do we expect delay to be update dynamically? If not, why not stick it in config space? > My feeling is that this should be a v1.0-only feature though > (eg. feature bit 33). > > Cheers, > Rusty. Yes, e.g. we can't extend config space for legacy virtio pci. > > Cc: Rusty Russell > > Cc: Michael S. Tsirkin > > Signed-off-by: Jason Wang > > --- > > drivers/net/virtio_net.c | 67 +++++++++++++++++++++++++++++++++++++++++ > > include/uapi/linux/virtio_net.h | 12 ++++++++ > > 2 files changed, 79 insertions(+) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index cc5f5de..2b958fb 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -145,6 +145,11 @@ struct virtnet_info { > > > > /* Budget for polling tx completion */ > > u32 tx_work_limit; > > + > > + __u32 rx_coalesce_usecs; > > + __u32 rx_max_coalesced_frames; > > + __u32 tx_coalesce_usecs; > > + __u32 tx_max_coalesced_frames; > > }; > > > > struct padded_vnet_hdr { > > @@ -1404,12 +1409,73 @@ static void virtnet_get_channels(struct net_device *dev, > > channels->other_count = 0; > > } > > > > +static int virtnet_set_coalesce(struct net_device *dev, > > + struct ethtool_coalesce *ec) > > +{ > > + struct virtnet_info *vi = netdev_priv(dev); > > + struct scatterlist sg; > > + struct virtio_net_ctrl_coalesce c; > > + > > + if (!vi->has_cvq || > > + !virtio_has_feature(vi->vdev, VIRTIO_NET_F_CTRL_COALESCE)) > > + return -EOPNOTSUPP; > > + if (vi->rx_coalesce_usecs != ec->rx_coalesce_usecs || > > + vi->rx_max_coalesced_frames != ec->rx_max_coalesced_frames) { > > + c.coalesce_usecs = ec->rx_coalesce_usecs; > > + c.max_coalesced_frames = ec->rx_max_coalesced_frames; > > + sg_init_one(&sg, &c, sizeof(c)); > > + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_COALESCE, > > + VIRTIO_NET_CTRL_COALESCE_RX_SET, > > + &sg)) { > > + dev_warn(&dev->dev, "Fail to set rx coalescing\n"); > > + return -EINVAL; > > + } > > + vi->rx_coalesce_usecs = ec->rx_coalesce_usecs; > > + vi->rx_max_coalesced_frames = ec->rx_max_coalesced_frames; > > + } > > + > > + if (vi->tx_coalesce_usecs != ec->tx_coalesce_usecs || > > + vi->tx_max_coalesced_frames != ec->tx_max_coalesced_frames) { > > + c.coalesce_usecs = ec->tx_coalesce_usecs; > > + c.max_coalesced_frames = ec->tx_max_coalesced_frames; > > + sg_init_one(&sg, &c, sizeof(c)); > > + if (!virtnet_send_command(vi, VIRTIO_NET_CTRL_COALESCE, > > + VIRTIO_NET_CTRL_COALESCE_TX_SET, > > + &sg)) { > > + dev_warn(&dev->dev, "Fail to set tx coalescing\n"); > > + return -EINVAL; > > + } > > + vi->tx_coalesce_usecs = ec->tx_coalesce_usecs; > > + vi->tx_max_coalesced_frames = ec->tx_max_coalesced_frames; > > + } > > + > > + vi->tx_work_limit = ec->tx_max_coalesced_frames_irq; > > + > > + return 0; > > +} > > + > > +static int virtnet_get_coalesce(struct net_device *dev, > > + struct ethtool_coalesce *ec) > > +{ > > + struct virtnet_info *vi = netdev_priv(dev); > > + > > + ec->rx_coalesce_usecs = vi->rx_coalesce_usecs; > > + ec->rx_max_coalesced_frames = vi->rx_max_coalesced_frames; > > + ec->tx_coalesce_usecs = vi->tx_coalesce_usecs; > > + ec->tx_max_coalesced_frames = vi->tx_max_coalesced_frames; > > + ec->tx_max_coalesced_frames_irq = vi->tx_work_limit; > > + > > + return 0; > > +} > > + > > static const struct ethtool_ops virtnet_ethtool_ops = { > > .get_drvinfo = virtnet_get_drvinfo, > > .get_link = ethtool_op_get_link, > > .get_ringparam = virtnet_get_ringparam, > > .set_channels = virtnet_set_channels, > > .get_channels = virtnet_get_channels, > > + .set_coalesce = virtnet_set_coalesce, > > + .get_coalesce = virtnet_get_coalesce, > > }; > > > > #define MIN_MTU 68 > > @@ -2048,6 +2114,7 @@ static unsigned int features[] = { > > VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, > > VIRTIO_NET_F_CTRL_MAC_ADDR, > > VIRTIO_F_ANY_LAYOUT, > > + VIRTIO_NET_F_CTRL_COALESCE, > > }; > > > > static struct virtio_driver virtio_net_driver = { > > diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h > > index b5f1677..332009d 100644 > > --- a/include/uapi/linux/virtio_net.h > > +++ b/include/uapi/linux/virtio_net.h > > @@ -34,6 +34,7 @@ > > /* The feature bitmap for virtio net */ > > #define VIRTIO_NET_F_CSUM 0 /* Host handles pkts w/ partial csum */ > > #define VIRTIO_NET_F_GUEST_CSUM 1 /* Guest handles pkts w/ partial csum */ > > +#define VIRTIO_NET_F_CTRL_COALESCE 3 /* Set coalescing */ > > #define VIRTIO_NET_F_MAC 5 /* Host has given MAC address. */ > > #define VIRTIO_NET_F_GSO 6 /* Host handles pkts w/ any GSO type */ > > #define VIRTIO_NET_F_GUEST_TSO4 7 /* Guest can handle TSOv4 in. */ > > @@ -202,4 +203,15 @@ struct virtio_net_ctrl_mq { > > #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN 1 > > #define VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX 0x8000 > > > > +struct virtio_net_ctrl_coalesce { > > + __u32 coalesce_usecs; > > + __u32 max_coalesced_frames; > > +}; > > + > > +#define VIRTIO_NET_CTRL_COALESCE 6 > > + #define VIRTIO_NET_CTRL_COALESCE_TX_SET 0 > > + #define VIRTIO_NET_CTRL_COALESCE_TX_GET 1 > > + #define VIRTIO_NET_CTRL_COALESCE_RX_SET 2 > > + #define VIRTIO_NET_CTRL_COALESCE_RX_GET 3 > > + > > #endif /* _LINUX_VIRTIO_NET_H */ > > -- > > 1.8.3.1