freebsd router

[Danial Thom]

--- "Matthew D. Fuller"
<fullermd at over-yonder.net> wrote:

> On Wed, Jan 11, 2006 at 07:22:15AM -0800 I
> heard the voice of
> Danial Thom, and lo! it spake thus:
> >
> > You're basically limited in an MP environment
> to sucking the packet
> > out of the ring and throwing it into a queue.
> 
> I can only presume you're being willfully
> silly.  An MP environment is
> quite capable of grabbing the packet from an
> interface, and then
> CONTINUING TO PROCESS IT while the other CPU
> grabs the next packet and
> starts processing it.  You can process through
> to completion JUST as
> easily on a MP system as you can on a UP
> system, except that you're
> not blocking the next packet while you do it. 
> Furthermore, you've got
> another CPU to do things like update the
> routing table and deal with
> OTHER interrupts and kernel tasks at the same
> time.

and another concept you fail to grasp is that
with 1 processor the data for the entire
transaction sits in the cpu cache, whereas with 2
it has to be read again. Its not necessarily
desireable to have 2 processors working on the
same data. There are a lot of issues that aren't
as black and white as "2 processors must be
faster than 1". 

DT

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