Re: packet re-ordering on SMP machines.

[Alan Cox]

On Sun, 2002-08-25 at 08:18, Ben Greear wrote:
> By re-ordered, I mean that a method called from process_backlog in dev.c
> is being handed packets in a different order than they are being poked into
> the driver with hard_start_xmit on the other interface.  If each CPU can be running the
> process_backlog, then I can see how this could be happening.
> 
> 
> 1)  Is this expected behaviour?
Yes

> 2)  Is there any standard (ie configurable) way to enforce strict ordering on an
>      SMP system?
No

> 3)  If answer to 2 is no, would you all be interested in a patch that
>      did allow strict ordering (if indeed I can figure out how to write one)?

You should never need it. Ethernet, hubs, switches, routers, internet
backbones etc will all cause packet re-ordering. You should also expect
the percentage of re-ordered frames on the net to rise and rise.