[Bloat] buffer sizing meeting notes

[Sebastian Moeller]

Another nugget from the notes (http://yuba.stanford.edu/~bspang/buffer-sizing-meeting/notes/):

Chuanxiong Guo, Bytedance

Talked about buffering in Bytedance’s datacenters. The top of rack switches have buffers of 12-32MB, and the aggregation switches have larger buffers of several GB. Were hoping to use ECN to reduce buffers for aggregation switches, but argued that precise ECN marking on egress queue length in VoQs is hard. However, Arista and Barefoot said they’ve fixed this using the packet latency instead of queue length for ECN.

This looks like an argument for fq_codel/cake's use of time instead of queue length, OR an argument for fq, because in a non-overwhelmed fq_system the local bucket's queue length should be somewhat stronger correlated with the sojurn times, than the sojurn time of a packet though a shared queue, no?

Best Regards
	Sebastian 

> On Aug 24, 2019, at 09:54, Jesper Dangaard Brouer <brouer at redhat.com> wrote:
> 
> On Fri, 23 Aug 2019 10:13:39 -0700
> Simon Barber <simon at superduper.net> wrote:
> 
>>> On Aug 23, 2019, at 9:07 AM, Dave Taht <dave.taht at gmail.com> wrote:
>>> 
>>> There's some good preso from various representatives in the dc market here.
>>> 
>>> The p4 stuff, in particular (from barefoot) is looking impressive.
>>> 
>>> http://yuba.stanford.edu/~bspang/buffer-sizing-meeting/
> 
> I followed the link to the animation of AIMD (Additive
> Increase/Multiplicative Decrease), that was really cool!
> 
> https://dabh.github.io/network_animations/
> 
> -- 
> Best regards,
>  Jesper Dangaard Brouer
>  MSc.CS, Principal Kernel Engineer at Red Hat
>  LinkedIn: http://www.linkedin.com/in/brouer
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