[Bloat] CAKE in openwrt high CPU

[Toke Høiland-Jørgensen]

Sebastian Moeller <moeller0 at gmx.de> writes:

> Hi Toke,
>
>
>> On Sep 1, 2020, at 18:11, Toke Høiland-Jørgensen via Bloat <bloat at lists.bufferbloat.net> wrote:
>> 
>> Jonathan Foulkes <jf at jonathanfoulkes.com> writes:
>> 
>>> Toke, that link returns a 404 for me.
>> 
>> Ah, seems an extra character snuck in at the end - try this:
>> 
>> https://github.com/dtaht/sch_cake/commit/3152477235c934022049fcddc063c45d37ec10e6
>> 
>>> For others, I’ve found that testing cake throughput with isolation options enabled is tricky if there are many competing connections. 
>>> Like I keep having to tell my customers, fairness algorithms mean no one device will ever gain 100% of the bandwidth so long as there are other open & active connections from other devices.
>>> 
>>> That said, I’d love to find options to increase throughput for
>>> single-tin configs.
>> 
>> Yeah, doing something about this is on my list, one way or another. Not
>> sure how much more we can do in terms of overhead, so we may have to go
>> for multi-q (and multi-CPU) support. How many CPU cores does the
>> IQrouter have?
>
> 	It might be worth looking how the typical two cake instances
> 	distribute across the available CPUs, in some version of OpenWrt
> 	all cake's and ethernet interupt processing crowed up on a
> 	single CPU leading to "out of CPU" behaviour with 50% idle
> 	remaining... I think that usinf a different RPS scheme might
> 	work better.

Well, many home routers don't have any functional RPS at all. Also, it
doesn't help since CAKE takes the global qdisc lock. Both of those
issues should be fixed, ideally :)

-Toke