Re: poor network loopback performance and scalability

[David Miller <davem@davemloft.net>]

From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 21 Apr 2008 10:11:03 +0200

> 
> * David Miller <davem@davemloft.net> wrote:
> 
> > To move things forward, we should look into doing something similar to 
> > what Al Viro suggested, which would be to return an SKB pointer from 
> > the transmit path and call back into netif_receive_skb() using that.
> 
> yep, basically the sk_peer trick that AF_UNIX is already using.

Please read again, that isn't the suggestion being discussed.

What's being discussed is having the top of the transmit call path
getting a socket "buffer" pointer, that it can feed back into the
packet input path directly.  Loopback would return buffer pointers
from ->hard_start_xmit() instead of passing them netif_rx().  The top
of the transmit call path, upon getting a non-NULL buffer returned,
would pass it to netif_receive_skb().

We're not talking about sockets, although that is another idea (which
I'm working on a patch for, and I have a mechanism for what you refer
to as "path validation").