On Sat, Oct 12, 2019 at 03:57:21PM +0800, Jason Wang wrote: > > On 2019/10/12 上午9:53, prashantbhole.linux@xxxxxxxxx wrote: > > From: Prashant Bhole <prashantbhole.linux@xxxxxxxxx> > > > > vhost_net needs to peek tun packet sizes to allocate virtio buffers. > > Currently it directly accesses tap ptr ring to do it. Jason Wang > > suggested to achieve this using msghdr->msg_control and modifying the > > behavior of tap recvmsg. > > > Note this may use more indirect calls, this could be optimized in the future > by doing XDP/skb receiving by vhost_net its own. So it looks like this is going in the reverse direction, moving more data path code from vhost to tun. What's the point of the patchset then? > > > > > This change will be useful in future in case of virtio-net XDP > > offload. Where packets will be XDP processed in tap recvmsg and vhost > > will see only non XDP_DROP'ed packets. > > > > Patch 1: reorganizes the tun_msg_ctl so that it can be extended by > > the means of different commands. tap sendmsg recvmsg will behave > > according to commands. > > > > Patch 2: modifies recvmsg implementation to produce packet pointers. > > vhost_net uses recvmsg API instead of ptr_ring_consume(). > > > > Patch 3: removes ptr ring usage in vhost and functions those export > > ptr ring from tun/tap. > > > > Prashant Bhole (3): > > tuntap: reorganize tun_msg_ctl usage > > vhost_net: user tap recvmsg api to access ptr ring > > tuntap: remove usage of ptr ring in vhost_net > > > > drivers/net/tap.c | 44 ++++++++++++++--------- > > drivers/net/tun.c | 45 +++++++++++++++--------- > > drivers/vhost/net.c | 79 ++++++++++++++++++++++-------------------- > > include/linux/if_tun.h | 9 +++-- > > 4 files changed, 103 insertions(+), 74 deletions(-) > > > It would be helpful that if you can share some performance numbers here. > > Thanks
