[Codel] In which terms ath9k queuing limits fq_codel?

[Alessandro Bolletta <alessandro@mediaspot.net>]

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Hi,
I have a doubt about the problem that fq_codel has with 802.11n packet aggregation, and your help to understand the problem would be well accepted.

Could you explain me how and in which real terms (for example, through an example) ath9k underlaying queue will limit fq_codel effect?
I imagine that ath9k will only add some delay that can't be controlled by fq_codel, but I can't imagine how delay could grow in case of fillfullment of ath9k's queue...

Also, I read that fq_codel drops packets at head of queue. So, if fq_codel can't manage and act over ath9k queue, will fq_codel's effect change and not to work as expected? I'm thinking, for example, at the most common TCP congestion control techniques: will TCP be able to correctly understand what fq_codel wanted to announce, if it isn't droping packets at the very first level of queuing?

Thanks

Alessandro Bolletta



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