Re: [RFC PATCH net-next 00/12] XDP batching for TUN/vhost_net

Michael S. Tsirkin
2018-05-25T17:53:13Z

On Mon, May 21, 2018 at 05:04:21PM +0800, Jason Wang wrote:
> Hi all:
>
> We do not support XDP batching for TUN since it can only receive one
> packet a time from vhost_net. This series tries to remove this
> limitation by:
>
> - introduce a TUN specific msg_control that can hold a pointer to an
> array of XDP buffs
> - try copy and build XDP buff in vhost_net
> - store XDP buffs in an array and submit them once for every N packets
> from vhost_net
> - since TUN can only do native XDP for datacopy packet, to simplify
> the logic, split datacopy out logic and only do batching for
> datacopy.

I like how this rework looks. Pls go ahead and repost as
non-RFC.

> With this series, TX PPS can improve about 34% from 2.9Mpps to
> 3.9Mpps when doing xdp_redirect_map between TAP and ixgbe.
>
> Thanks
>
> Jason Wang (12):
> vhost_net: introduce helper to initialize tx iov iter
> vhost_net: introduce vhost_exceeds_weight()
> vhost_net: introduce vhost_has_more_pkts()
> vhost_net: split out datacopy logic
> vhost_net: batch update used ring for datacopy TX
> tuntap: enable premmption early
> tuntap: simplify error handling in tun_build_skb()
> tuntap: tweak on the path of non-xdp case in tun_build_skb()
> tuntap: split out XDP logic
> vhost_net: build xdp buff
> vhost_net: passing raw xdp buff to tun
> vhost_net: batch submitting XDP buffers to underlayer sockets
>
> drivers/net/tun.c | 226 +++++++++++++++++++++++++++----------
> drivers/vhost/net.c | 297 ++++++++++++++++++++++++++++++++++++++++++++-----
> include/linux/if_tun.h | 7 ++
> 3 files changed, 444 insertions(+), 86 deletions(-)
>
> --
> 2.7.4