Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751677AbbBJGvq (ORCPT ); Tue, 10 Feb 2015 01:51:46 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58068 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750791AbbBJGvo (ORCPT ); Tue, 10 Feb 2015 01:51:44 -0500 Date: Tue, 10 Feb 2015 06:59:30 +0008 From: Jason Wang Subject: Re: [PATCH RFC v5 net-next 4/6] virtio-net: add basic interrupt coalescing support To: Rusty Russell Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, mst@redhat.com, pagupta@redhat.com Message-Id: <1423551090.897.1@smtp.corp.redhat.com> In-Reply-To: <87386ey2iy.fsf@rustcorp.com.au> 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=utf-8; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7044 Lines: 196 On Tue, Feb 10, 2015 at 9:32 AM, 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])) Yes. This looks better and we don't even need device specific configuration method. > > 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. Can we give a device specific meaning for this? For virtio-net, we want to expose the coalescing settings through ethtool (tx-frames). And it was usually used with a timer, so probably another field after vring_used_delay() for this timer interval to trigger the interrupt if no new used buffers come after this interval. > > > My feeling is that this should be a v1.0-only feature though > (eg. feature bit 33). Yes it should. > > Cheers, > Rusty. > >> 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 > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/