Subject: Re: [PATCH 00/33] virtio-net: support AF_XDP zero copy

From: "Michael S. Tsirkin" <[email-masked]>
Date: Fri, 3 Feb 2023 04:08:31 -0500

On Thu, Feb 02, 2023 at 07:44:07PM +0800, Xuan Zhuo wrote:
> On Thu, 2 Feb 2023 06:08:30 -0500, "Michael S. Tsirkin" <[email-masked]> wrote:
> > On Thu, Feb 02, 2023 at 07:00:25PM +0800, Xuan Zhuo wrote:
> > > 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.
> >
> > Great! Any numbers to share?
> 
> RESEND. Last mail has some email format error.
> 
> ENV: Qemu with vhost.
> 
>                    vhost cpu | Guest APP CPU |Guest Softirq CPU | PPS
> -----------------------------|---------------|------------------|------------
> xmit by sockperf:     90%    |   100%        |                  |  318967
> xmit by xsk:          100%   |   30%         |   33%            | 1192064
> recv by sockperf:     100%   |   68%         |   100%           |  692288
> recv by xsk:          100%   |   33%         |   43%            |  771670
> 
> Thanks.

Impressive, thanks a lot for this work!
Pls remember to retest and include up to date numbers on
subsequent versions.

> 
> >
> > > mlx5 and intel ixgbe already support
> > > this feature, This patch set allows virtio-net to support xsk's zerocopy xmit
> > > feature.
> > >
> > > Virtio-net did not support per-queue reset, so it was impossible to support XDP
> > > Socket Zerocopy. At present, we have completed the work of Virtio Spec and
> > > Kernel in Per-Queue Reset. It is time for Virtio-Net to complete the support for
> > > the XDP Socket Zerocopy.
> > >
> > > Virtio-net can not increase the queue at will, so xsk shares the queue with
> > > kernel.
> > >
> > > On the other hand, Virtio-Net does not support generate interrupt 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 sofrirqd.
> > >
> > > Please review.
> > >
> > > Thanks.
> > >
> > >
> > > Xuan Zhuo (33):
> > >   virtio_ring: virtqueue_add() support premapped
> > >   virtio_ring: split: virtqueue_add_split() support premapped
> > >   virtio_ring: packed: virtqueue_add_packed() support premapped
> > >   virtio_ring: introduce virtqueue_add_outbuf_premapped()
> > >   virtio_ring: introduce virtqueue_add_inbuf_premapped()
> > >   virtio_ring: introduce virtqueue_reset()
> > >   virtio_ring: add api virtio_dma_map() for advance dma
> > >   virtio_ring: introduce dma sync api for virtio
> > >   xsk: xsk_buff_pool add callback for dma_sync
> > >   xsk: support virtio DMA map
> > >   virtio_net: rename free_old_xmit_skbs to free_old_xmit
> > >   virtio_net: unify the code for recycling the xmit ptr
> > >   virtio_net: virtnet_poll_tx support rescheduled
> > >   virtio_net: independent directory
> > >   virtio_net: move to virtio_net.h
> > >   virtio_net: introduce virtnet_xdp_handler() to seprate the logic of
> > >     run xdp
> > >   virtio_net: receive_small() use virtnet_xdp_handler()
> > >   virtio_net: receive_merageable() use virtnet_xdp_handler()
> > >   virtio_net: introduce virtnet_tx_reset()
> > >   virtio_net: xsk: introduce virtnet_rq_bind_xsk_pool()
> > >   virtio_net: xsk: introduce virtnet_xsk_pool_enable()
> > >   virtio_net: xsk: introduce xsk disable
> > >   virtio_net: xsk: support xsk setup
> > >   virtio_net: xsk: stop disable tx napi
> > >   virtio_net: xsk: __free_old_xmit distinguishes xsk buffer
> > >   virtio_net: virtnet_sq_free_unused_buf() check xsk buffer
> > >   virtio_net: virtnet_rq_free_unused_buf() check xsk buffer
> > >   net: introduce napi_tx_raise()
> > >   virtio_net: xsk: tx: support tx
> > >   virtio_net: xsk: tx: support wakeup
> > >   virtio_net: xsk: tx: auto wakeup when free old xmit
> > >   virtio_net: xsk: rx: introduce add_recvbuf_xsk()
> > >   virtio_net: xsk: rx: introduce receive_xsk() to recv xsk buffer
> > >
> > >  MAINTAINERS                                 |   2 +-
> > >  drivers/net/Kconfig                         |   8 +-
> > >  drivers/net/Makefile                        |   2 +-
> > >  drivers/net/virtio/Kconfig                  |  11 +
> > >  drivers/net/virtio/Makefile                 |   8 +
> > >  drivers/net/{virtio_net.c => virtio/main.c} | 564 +++++++-------------
> > >  drivers/net/virtio/virtio_net.h             | 317 +++++++++++
> > >  drivers/net/virtio/xsk.c                    | 524 ++++++++++++++++++
> > >  drivers/net/virtio/xsk.h                    |  33 ++
> > >  drivers/virtio/virtio_ring.c                | 376 +++++++++++--
> > >  include/linux/netdevice.h                   |   7 +
> > >  include/linux/virtio.h                      |  29 +
> > >  include/net/xsk_buff_pool.h                 |   6 +
> > >  net/core/dev.c                              |  11 +
> > >  net/xdp/xsk_buff_pool.c                     |  79 ++-
> > >  15 files changed, 1541 insertions(+), 436 deletions(-)
> > >  create mode 100644 drivers/net/virtio/Kconfig
> > >  create mode 100644 drivers/net/virtio/Makefile
> > >  rename drivers/net/{virtio_net.c => virtio/main.c} (92%)
> > >  create mode 100644 drivers/net/virtio/virtio_net.h
> > >  create mode 100644 drivers/net/virtio/xsk.c
> > >  create mode 100644 drivers/net/virtio/xsk.h
> > >
> > > --
> > > 2.32.0.3.g01195cf9f
> >