[Starlink] Re: Bufferbloat cure question

[David Lang <david@lang.hm>]

Colin_Higbie wrote:

> At 300Mbps or higher, bufferbloat and jitter skyrocket to hundreds of ms, much 
> worse than not using CAKE at all. I can see one of the 4 router CPU cores 
> spikes to 100% at those transfer rates whenever I don't limit bandwidth to 
> something below 280Mbps.

I know I've seen some patches going past in the last couple of months to let 
cake use more than one CPU, so you may want to look at testing those.

it's not uncommon for access points to run out of CPU when processing large 
packet volumes (with or without cake), the wndr3700/3800 series that we started 
with on the bufferbloat project would run out of steam at about that speed 
without any traffic shaping at all.

it's not just a matter of cpu cycles, it also starts to hit memory and MIC 
connection limits.

you may be able to get to high speeds if you don't try to have Cake completely 
eliminate the effect of bloat, just mitigate it to an acceptale level.

Unfortunantly, I don't know of anyone doing any benchmark testing of routers. 
This isn't just a problem at the low end, It's an industry joke that Cisco speed 
ratings are "we guarantee that no matter what you do you will never go faster 
than this", and that real performance can be as bad as 10% of what the speed 
ratings list.

David Lang