DP performance

[Danial Thom]

--- Erik Wikström <erik-wikstrom at xxxxxxxxx>
wrote:

> On 2005-12-02 19:16, Danial Thom wrote:
> > All of the empirical evidence points to Matt
> > being wrong. If you still can't accept that
> then
> > DFLY is more of a religion than a project,
> which
> > is damn shame.
> > 
> > DT
> 
> Since I don't know anything about networking at
> GigE-speed I find this 
> whole diskussion very interesting and I hope to
> learn something new. 
> However, as always when two people both believe
> they are right, it's 
> hard for me to really choos whom to trust.
> 
> However Matt has provided some arguments that I
> find very convincing 
> (calculations and reasoning). Now, since you
> say that all empirical 
> evidence suggest that he is wrong I suppose
> that you have some other 
> numbers (wouldn't be very empirical otherwise
> would it?) that you could 
> show me (like benchmarking or such). Then I
> might decide what to think 
> when I've seen both sides arguments.

Matt admits that he's "not sure" how the PCI bus
works, so why do you find his "calculations"
convincing? He can't possibly do calculations if
he doesn't understand the impact of the bus on
the operations in question. Try profiling a
kernel thats doing nothing but bridging packets.
His arguement that hardly any CPU is used is
foolish and wrong. There are millions of
operations required to move a packet from one
interface to another. You can't explain that in
A+B=C math. You have to do real testing.

Why do you think that flow-controlling a gigabit
switch is an "ok" solution? What do you think the
switch is going to do with the traffic? Its going
to dump it. So you've moved the dropped packets
from one box to another; the result is still
packet loss. You've solved nothing. 

None of his answers address the original
question, which is when will MP be as fast or
close to as fast as UP. His answer is that
networking takes no CPU cycles. Its the dumbest
thing I've ever heard.


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