[Codel] Finite-Buffer M/G/1 Queues with Time and Space Priorities

Luca Muscariello muscariello at ieee.org
Wed Jul 27 13:23:34 EDT 2022

On Wed 27 Jul 2022 at 17:34, Dave Taht <dave.taht at gmail.com> wrote:

> Occasionally I pass along a recent paper that I don't understand in
> the hope that someone can enlighten me.
> This is one of those occasions, where I am trying to leverage what I
> understand of existing FQ-codel behaviors against real traffic.

I’m not sure how realistic the model is. The delay-sensitive class gets
non-preemptive service prioritization over the loss-sensitive class (
dequeue time) So far so good.
The loss-sensitive class can take advantage of the presence of
delay-sensitive packets in the queue at enqueue time if the buffer is full
by dropping delay sensitive traffic.

I don’t think it models anything useful for fq-codel.
It might be a model for loss-less networks  like fiber channel or things
like NVMe over  Fabric with Ethernet as fabric.

> https://www.hindawi.com/journals/mpe/2022/4539940/
> Compared to the previous study on finite-buffer M/M/1 priority queues
> with time and space priority, where service times are identical and
> exponentially distributed for both types of traffic, in our model we
> assume that service times are different and are generally distributed
> for different types of traffic. As a result, our model is more
> suitable for the performance analysis of communication systems
> accommodating multiple types of traffic with different service-time
> distributions. For the proposed queueing model, we derive the
> queue-length distributions, loss probabilities, and mean waiting times
> of both types of traffic, as well as the push-out probability of
> delay-sensitive traffic.
> --
> FQ World Domination pending:
> https://blog.cerowrt.org/post/state_of_fq_codel/
> Dave Täht CEO, TekLibre, LLC
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