Re: [LARTC] CBQ and WRR

[jamal <hadi@cyberus.ca>]

On Wed, 28 Mar 2001, Christian Worm Mortensen wrote:

> Maybe I will read it some day ;-)

I think you _Must_ (especially if you are implementing WRR). There are
some good ideas there

>
> > but fixing the deficit such that you
> > take into consideration 'byte credit' a queue has when you preempt it
> > makes a WRR implementation closer to DRR.
>
> Well, the WRR qdisc essentially works this way:
>
> * For each band (=class) there is a byte counter
> * When a band transfers a packet the byte counter is
>    increased by the packet size divided with the weight (which is a
>    number between 0 and 1)
> * The next band that can transfer a packet is always the one with the
>   lowest byte counter.
>
> It also does some additional things to make sure that when a new band
> has something to send it can send it immedialty. I don't see any way
> this scheme can be improved.
>

So is this decision on packet by packet?
I.e when do you decide that a 'band' should stop sending?
Are there opportunities that a 'band' could be starved?
Dont make me go read the Varghese paper again. You should ;->

> > The original CBQ implementation is the classical WRR;
>
> But it did not take the packet size into account?

It didnt.

cheers,
jamal


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