Re: Van Jacobson's net channels and real-time

[Ingo Oeser <ioe-lkml@rameria.de>]

Hi Jörn,

On Saturday, 22. April 2006 13:48, Jörn Engel wrote:
> Unless I completely misunderstand something, one of the main points of
> the netchannels if to have *zero* fields written to by both producer
> and consumer. 

Hmm, for me the main point was to keep the complete processing
of a single packet within one CPU/Core where this is a non-issue.

> Receiving and sending a lot can be expected to be the 
> common case, so taking a performance hit in this case is hardly a good
> idea.

There is no hit. If you receive/send in bursts you can simply aggregate
them until a certain queueing threshold. 

The queue design outlined can split the queueing in reserve and commit stages,
where the producer can be told how much in can produce and the consumer is
told  how much it can consume. 

Within their areas the producer and consumer can freely move around.
So this is not exactly a queue, but a dynamic double buffer :-)

So maybe doing queueing with the classic head/tail variant is better here,
but the other variant might replace it without problems and allows
for some nice improvements.


Regards

Ingo Oeser