[Bloat] when does the CoDel part of fq_codel help in the real world?

Mikael Abrahamsson swmike at swm.pp.se
Tue Nov 27 06:21:48 EST 2018


On Tue, 27 Nov 2018, Luca Muscariello wrote:

> A BDP is not a large buffer. I'm not unveiling a secret.

It's complicated. I've had people throw in my face that I need 2xBDP in 
buffer size to smoothe things out. Personally I don't want more than 10ms 
buffer (max), and I don't see why I should need more than that even if 
transfers are running over hundreds of ms of light-speed-in-medium induced 
delay between the communicating systems.

I have routers that are perfectly capable at buffering packets for 
hundreds of ms even at hundreds of megabits/s of access speed. I choose 
not to use them though, and configure them to drop packets much earlier.

> My point was that FQ_codel helps to get very close to the optimum w/o 
> adding useless queueing and latency. With a single queue that's almost 
> impossible. No, sorry. Just impossible.

Right, I realise I wasn't clear I wasn't actually commenting on your 
specific text directly, my question was more generic.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se



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