[Bloat] Up-to-date buffer sizes?

[David Lang]

If the link is not a bottleneck, then you will not be using buffers (whatever 
they are configured to be)

networking gear tends toward the proprietary (although there's a growing amount 
that's linux based now) and they tend to be very closed mouth about 
configuration like this.

David Lang

  On Wed, 9 Mar 2022, Michael Menth wrote:

> Date: Wed, 9 Mar 2022 18:39:08 +0100
> From: Michael Menth <menth at uni-tuebingen.de>
> To: Jesper Dangaard Brouer <jbrouer at redhat.com>,
>     Toke Høiland-Jørgensen <toke at toke.dk>, bloat <bloat at lists.bufferbloat.net>
> Subject: Re: [Bloat] Up-to-date buffer sizes?
> 
> Hi all,
>
> I don't question the usefulness of AQMs for buffers - on the contrary. 
> But what are up-to-date buffer sizes in networking gears, especially if 
> AQMs are not in use? It's hard to find public and information about it. 
> Anyone can point to a citable source?
>
> This raises also the question about the deployment of AQMs in networking 
> infrastructure. I know it's already adopted by some OSs, but what about 
> forwarding nodes? Any papers about it?
>
> Kind regards
>
> Michael
>
> Am 09.03.2022 um 18:24 schrieb Jesper Dangaard Brouer:
>> 
>> 
>> On 09/03/2022 17.31, Toke Høiland-Jørgensen via Bloat wrote:
>>> Michael Menth <menth at uni-tuebingen.de> writes:
>>>
>>>> Hi all,
>>>>
>>>> are there up-to-date references giving evidence about typical buffer
>>>> sizes for various link speeds and technologies?
>>>
>>> Heh. There was a whole workshop on it a couple of years ago; not sure if
>>> it concluded anything: http://buffer-workshop.stanford.edu/program/
>>>
>>> But really, asking about buffer sizing is missing the point; if you have
>>> static buffers with no other management (like AQM and FQ) you're most
>>> likely already doing it wrong... :)
>> 
>> Exactly, I agree with Toke. The important parameter is the latency.
>> Or the packet sojourn time (rfc8289 + rfc8290) observed waiting in the 
>> queue.
>> 
>> The question you should be asking is:
>>   - What is the max queue latency I'm "willing" to experience on this link?
>> 
>> Hint, you can then depending on the link rate calculate the max buffer 
>> size you should configure.
>> 
>> The short solution is:
>>   - just use fq_codel (rfc8290) as the default qdisc.
>> 
>> --Jesper
>> 
>> 
>> 
>
>