Re: [PATCH net-next v8 00/10] virtio-net: support AF_XDP zero copy

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jul 08, 2024 at 07:25:27PM +0800, Xuan Zhuo wrote:
> v8:
>     1. virtnet_add_recvbuf_xsk() always return err, when encounters error
> 
> v7:
>     1. some small fixes
> 
> v6:
>     1. start from supporting the rx zerocopy
> 
> v5:
>     1. fix the comments of last version
>         http://lore.kernel.org/all/20240611114147.31320-1-xuanzhuo@linux.alibaba.com
> v4:
>     1. remove the commits that introduce the independent directory
>     2. remove the supporting for the rx merge mode (for limit 15
>        commits of net-next). Let's start with the small mode.
>     3. merge some commits and remove some not important commits


Series:

Acked-by: Michael S. Tsirkin <mst@redhat.com>

> ## AF_XDP
> 
> XDP socket(AF_XDP) is an excellent bypass kernel network framework. The zero
> copy feature of xsk (XDP socket) needs to be supported by the driver. The
> performance of zero copy is very good. mlx5 and intel ixgbe already support
> this feature, This patch set allows virtio-net to support xsk's zerocopy xmit
> feature.
> 
> At present, we have completed some preparation:
> 
> 1. vq-reset (virtio spec and kernel code)
> 2. virtio-core premapped dma
> 3. virtio-net xdp refactor
> 
> So it is time for Virtio-Net to complete the support for the XDP Socket
> Zerocopy.
> 
> Virtio-net can not increase the queue num at will, so xsk shares the queue with
> kernel.
> 
> On the other hand, Virtio-Net does not support generate interrupt from driver
> manually, so when we wakeup tx xmit, we used some tips. If the CPU run by TX
> NAPI last time is other CPUs, use IPI to wake up NAPI on the remote CPU. If it
> is also the local CPU, then we wake up napi directly.
> 
> This patch set includes some refactor to the virtio-net to let that to support
> AF_XDP.
> 
> ## Run & Test
> 
> Because there are too many commits, the work of virtio net supporting af-xdp is
> split to rx part and tx part. This patch set is for rx part.
> 
> So the flag NETDEV_XDP_ACT_XSK_ZEROCOPY is not added, if someone want to test
> for af-xdp rx, the flag needs to be adding locally.
> 
> ## performance
> 
> ENV: Qemu with vhost-user(polling mode).
> Host CPU: Intel(R) Xeon(R) Platinum 8163 CPU @ 2.50GHz
> 
> ### virtio PMD in guest with testpmd
> 
> testpmd> show port stats all
> 
>  ######################## NIC statistics for port 0 ########################
>  RX-packets: 19531092064 RX-missed: 0     RX-bytes: 1093741155584
>  RX-errors: 0
>  RX-nombuf: 0
>  TX-packets: 5959955552 TX-errors: 0     TX-bytes: 371030645664
> 
> 
>  Throughput (since last show)
>  Rx-pps:   8861574     Rx-bps:  3969985208
>  Tx-pps:   8861493     Tx-bps:  3969962736
>  ############################################################################
> 
> ### AF_XDP PMD in guest with testpmd
> 
> testpmd> show port stats all
> 
>   ######################## NIC statistics for port 0  ########################
>   RX-packets: 68152727   RX-missed: 0          RX-bytes:  3816552712
>   RX-errors: 0
>   RX-nombuf:  0
>   TX-packets: 68114967   TX-errors: 33216      TX-bytes:  3814438152
> 
>   Throughput (since last show)
>   Rx-pps:      6333196          Rx-bps:   2837272088
>   Tx-pps:      6333227          Tx-bps:   2837285936
>   ############################################################################
> 
> But AF_XDP consumes more CPU for tx and rx napi(100% and 86%).
> 
> Please review.
> 
> Thanks.
> 
> v3
>     1. virtio introduces helpers for virtio-net sq using premapped dma
>     2. xsk has more complete support for merge mode
>     3. fix some problems
> 
> v2
>     1. wakeup uses the way of GVE. No send ipi to wakeup napi on remote cpu.
>     2. remove rcu. Because we synchronize all operat, so the rcu is not needed.
>     3. split the commit "move to virtio_net.h" in last patch set. Just move the
>        struct/api to header when we use them.
>     4. add comments for some code
> 
> v1:
>     1. remove two virtio commits. Push this patchset to net-next
>     2. squash "virtio_net: virtnet_poll_tx support rescheduled" to xsk: support tx
>     3. fix some warnings
> 
> 
> 
> 
> 
> 
> 
> 
> Xuan Zhuo (10):
>   virtio_net: replace VIRTIO_XDP_HEADROOM by XDP_PACKET_HEADROOM
>   virtio_net: separate virtnet_rx_resize()
>   virtio_net: separate virtnet_tx_resize()
>   virtio_net: separate receive_buf
>   virtio_net: separate receive_mergeable
>   virtio_net: xsk: bind/unbind xsk for rx
>   virtio_net: xsk: support wakeup
>   virtio_net: xsk: rx: support fill with xsk buffer
>   virtio_net: xsk: rx: support recv small mode
>   virtio_net: xsk: rx: support recv merge mode
> 
>  drivers/net/virtio_net.c | 770 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 676 insertions(+), 94 deletions(-)
> 
> --
> 2.32.0.3.g01195cf9f