[Cake] [NetDev-People] 0x19: Talk, mq-cake: Scaling software rate limiting across CPU cores

[Toke Høiland-Jørgensen]

Sebastian Moeller <moeller0 at gmx.de> writes:

> Hi Toke,
>
>
>> On 10. Feb 2025, at 11:35, Toke Høiland-Jørgensen <toke at redhat.com> wrote:
>> 
>> Sebastian Moeller <moeller0 at gmx.de> writes:
>> 
>>> That sounds most excellent...
>>> 
>>> This also means that now we need cheap router hardware with > 2 NIC
>>> queues and > 2 CPUs ;) (with ingress and egress shaping the current
>>> state is that 2 CPUs can be utilised).
>> 
>> Well, even if there are only 2 CPUs, the MQ version can utilise both of
>> those in one direction, which helps for asymmetrical traffic :)
>
> Fair point, I was thinking bi directional saturating traffic on a
> symmetric link, which I guess is far from the typical use case ;)

Exactly :)

>> 
>>> I wonder, does this work for IFBs as well or only for real hardware
>>> NIC queues?
>> 
>> Yup, you can specify the number of TX queues on an ifb interface when
>> creating it (ip link add numtxqueues 2 type ifb).
>
> Great, so this will then work even if the true NIC hardware is not
> multi-queue capable or does numtxqueues need to be <= true number of
> NIC queues?

Hmm, no, ifb queues are independent, so yeah, I guess ingress shaping
could scale regardless of the number of HWQs...

-Toke