Subject: Re: [PATCH net-next 2/2] virtio-net: simplify XDP handling in small buffer

From: Jesper Dangaard Brouer <[email-masked]>
Date: Thu, 1 Mar 2018 10:15:53 +0100

On Thu, 1 Mar 2018 16:49:24 +0800
Jason Wang <[email-masked]> wrote:

> > 2. This can easily cause out-of-order packets.  
> 
> I may miss something, but it looks to me packets were still delivered
> in order? Or you mean the packets that was dropped by cpumap?

No. Packets can now travel two code paths to the egress device. (1) XDP
native via ndp_xdp_xmit via direct delivery into a lockfree/dedicated
TX queue, (2) via normal network stack which can involve being queue in
a qdisc.  Do you see the possibility of the reorder now?

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer