Re: [aqm] FQ-PIE kernel module implementation

[Fred Baker <[e-mail]>]

> On Jul 3, 2015, at 2:45 AM, Polina Goltsman <[e-mail]> wrote:
> 
> As I understand the FQ-Codel draft, it seems to be fundamental to FQ-Codel that each queue has separate state variables.
> So my question is: is it indeed fundamental ?

If you're asking whether it is fundamental to fair queuing, I'll recommend you start researching that question with RFC 970 and the articles in SIGCOMM and INFOCOMM on the topic circa 1988-1995 or so. Also take a look at Class-based Queing (aka CBQ) in the same timeframe. I think you'll find that FQ systems are not approached as collections of queues with different characteristics; they are collections of queues with essentially the same set of characteristics, using scheduling to make the queues share bandwidth in a manner similar to the Generalized Processor Sharing model. On the other hand, CBQ systems are systems with separate queues or classes for different sets of traffic, with different characteristics such as drop policy or target latency.

When we built the differentiated services model, we modeled a FQ subsystem as if it were a single queue in a larger CBQ system, We might, for example, have a FQ system for an AF class, but give EF priority over the entire FQ subsystem.