On Fri, 2004-11-26 at 10:31, Marco Mellia wrote:
> If you don't trust us, please, ignore this email.
Dont take it the wrong way please - nobody has been able to produce the
results you have. So thats why you may be getting that comment.
The fact you have been able to do this is a good thing.
> That's the number we have. And are actually very similar from what other
> colleagues of us got.
> The point is:
> while a PCI-X linux or (or click) box can receive (receive just up to
> the netif_receive_skb() level and then discard the skb) up to more than
> wire speed using off-the-shelf gigabit ethernet hardware, there is no
> way to transmit more than about half that speed. This is true
> considering minimum sized ethernet frames.
Hrm. I could not get more than 8-900Kpps on receive drop in the driver
on a super fast xeon. Can you post the diff for your driver?
My tests was with e1000.
What kind of hardware is this? Do you have a block diagram on how the
NIC is connected on the system? A lot of issues are dependent on how you
hardware hookup is.
> This holds true with
> - linux 2.4.x and 2.6.x and click-linux 2.4.x
> - intel e1000 or broadcom drivers (modified to drop packets after the
> - whichever driver version you like (with minor modifications).
> The only modification to the driver we did consists in carefully
> prefecting the data in the CPU internal cache.
prefetching as in the use of prefetch()?
What were you prefetching if you end up dropping packet?
> Some details and results can be retreived from
> Part of this results are presented in this paper
> A. Bianco, J.M. Finochietto, G. Galante, M. Mellia, F. Neri
> Open-Source PC-Based Software Routers: a Viable Approach to High-Performance
> Packet Switching
> Third Internation Workshop on QoS in Multiservice IP Networks
> Catania, Feb 2005
> Hope this helps.
Thanks i will read these papers.
Take a look at presentation i made at SUCON:
I have solved the problem which is identified in the first of slides
(just before "why me momma?" slide) - i could describe the solution and
even provide pathces which may address (perhaps) some of the transmit
issues you are seeing.