Re: [Qemu-devel] [PATCH 0/9] introduce virtio net dataplane

[Michael S. Tsirkin]

On Thu, Feb 21, 2013 at 08:54:44PM +0800, Liu Ping Fan wrote:
> This is a emulation to virtio-blk dataplane, which push the data
> handling out of biglock. And it is a try to implement this process
> in userspace, while vhost-net in kernel.

What's the motivation for doing this? Speed up the slirp backend
which vhost-net does not support? If yes, I would start with
implementing offloads (segmentation,checksum) in slirp.
This is likely to give you a nice speed boost and is
generally a desirable feature.

> The iperf's result show it improving the perfermance of base line,
> but still slower than vhost-net (maybe the rx path need optimized).
> 
> Todo:
> implement fine lock for net-subsystem

vhost-net is currently the only way to get zero copy transmit
on linux (and zero copy receive in the future)
so at least in theory it'll always be faster.

> Liu Ping Fan (9):
>   vring: split the modification and publish of used ring
>   vring: introduce vring_restore() to restore from img
>   event poll: make epoll work for normal fd
>   event poll: pass event type to event callback
>   event poll: enable event poll handle more than one event each time
>   virtio net: introduce dataplane for virtio net
>   tap: make tap peer work on dedicated data-plane thread
>   virtio net: enable dataplane for virtio net
>   configure: make virtio net dataplane configurable
> 
>  configure                  |   12 ++
>  hw/dataplane/Makefile.objs |    4 +-
>  hw/dataplane/event-poll.c  |   69 +++++--
>  hw/dataplane/event-poll.h  |   14 ++-
>  hw/dataplane/virtio-blk.c  |    8 +-
>  hw/dataplane/virtio-net.c  |  444 
> ++++++++++++++++++++++++++++++++++++++++++++
>  hw/dataplane/virtio-net.h  |   32 ++++
>  hw/dataplane/vring.c       |   37 ++++
>  hw/dataplane/vring.h       |    3 +
>  hw/virtio-net.c            |   94 +++++-----
>  hw/virtio-net.h            |   64 +++++++
>  hw/virtio-pci.c            |    2 +-
>  include/net/tap.h          |    6 +
>  net/tap.c                  |   92 +++++++++-
>  14 files changed, 806 insertions(+), 75 deletions(-)
>  create mode 100644 hw/dataplane/virtio-net.c
>  create mode 100644 hw/dataplane/virtio-net.h
> 
> -- 
> 1.7.4.4
>