[Cake] cake infinite loop(?) with hfsc on one-armed router

[Pete Heist]

> On Jan 6, 2019, at 9:56 PM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
> 
> Pete Heist <pete at heistp.net> writes:
> 
>> Lastly, is using cake as a leaf to htb risky until a fix is made? I’ve
>> been doing that for a while without any apparent issues, though I’m
>> hesitating now to try that in a production environment.
> 
> Hmm, that's a good question. I would expect so; but I would also expect
> the issue to show up pretty much straight away, so if you haven't hit it
> yet, I may be wrong. I'll do some more digging... Should probably also
> try to replicate all this stuff on my own machine :)


Ok, after what I’m seeing on my APU1 tests on 3.16.7, I’m definitely not putting split GSO into production. I just turned it on and off three times and here’s what I got:

Split GSO on:

https://www.heistp.net/downloads/htb_split_gso/htb_cake_split_gso.svg
https://www.heistp.net/downloads/htb_split_gso/htb_cake_split_gso2.svg
https://www.heistp.net/downloads/htb_split_gso/htb_cake_split_gso3.svg

Split GSO off:

https://www.heistp.net/downloads/htb_split_gso/htb_cake_no_split_gso.svg
https://www.heistp.net/downloads/htb_split_gso/htb_cake_no_split_gso2.svg
https://www.heistp.net/downloads/htb_split_gso/htb_cake_no_split_gso3.svg

I’ve seen these square waves before with htb and wondered where they came from, and I think we may finally have an answer! What manner of thing causes this I don’t know, but there’s a chance you may end up finding out… :)