Re: [tsvwg] L4S status: #17 Interaction w/ FQ AQMs

[Sebastian Moeller <[e-mail]>]

Hi Oliver,

I wonder how you intend to deal with scenario 1, cubic versus prague, where prague for short RTTs pummels cubic throughput, quite unlike what one naively could expect from reading the dualQ draft:

"Analytical study and implementation testing of the Coupled AQM have
   shown that Scalable and Classic flows competing under similar
   conditions run at roughly the same rate."

at 0ms RTT prague is ~10 times faster than cubic, and at 10ms this still is around a factor of 3, only at 80ms that gets into what I would consider "roughly the same rate". I now wonder what happens if you pair a short RTT (say 10ms) prague flow (simulating traffic from a nearby data center) with a cubic flow with a typical internet RTT (say 80ms). My prediction is that prague will dominate cubic similarly to the 0ms RTT. I guess this is coming from the default 1/16 scheduling weight for the normal queue, do you agree? 




> On Nov 8, 2019, at 11:41, Tilmans, Olivier (Nokia - BE/Antwerp) <[e-mail]> wrote:
> 
>> Hi Greg, would it be possible to merge any changes you’d like to include in
>> further testing into the testing (default) branch at
>> https://github.com/L4STeam/linux? We’ll evaluate what we can with what time
>> there is, but a prerequisite to that is making sure we have the right
>> changes you want tested. :)
> 
> Hi Pete,
> 
> As mentioned at https://l4s.cablelabs.com/l4s-testing/README.html (link
> at the bottom of the page Greg linked), we ran your full set of flent
> tests using this tag:
> https://github.com/L4STeam/linux/releases/tag/testing%2F5-11-2019 
> 
> I doubt we'll push anything else on that repo for the moment being
> unless someone comes out with a bug/fix/improvement. 

	Well, I would like to see scenario 1 with unequal RTTs between the two flows, like prague@10ms vs. cubic@80ms, and prage@80ms vs. cubic@10ms (and the same for cubic vs. cubic)
and I would like to see tests pitting 2 flows of one type versus one flow of the other type, like 2 cubic versus 1 prague and 2 prague vs. 1 cubic.

Best Regards
	Sebastian

> 
> 
> Best,
> Olivier