[Beowulf] anyone have modern interconnect metrics?

[Benson Muite]

Many clouds use COTS ethernet, eg. AWS, Alibaba, Oracle.  My expectation
is that most workloads that are tightly coupled are on hundreds of
nodes.  Networking is disaggreagated, so variance in latency will be
somewhat greater than a typical cluster, though some of the newer
topologies used in HPC can exhibit significant job interference.

On 17/01/2024 01.19, Mark Hahn wrote:
> Hi all,
> Just wondering if any of you have numbers (or experience) with
> modern high-speed COTS ethernet.
> 
> Latency mainly, but perhaps also message rate.  Also ease of use
> with open-source products like OpenMPI, maybe Lustre?
> Flexibility in configuring clusters in the >= 1k node range?
> 
> We have a good idea of what to expect from Infiniband offerings,
> and are familiar with scalable network topologies.
> But vendors seem to think that high-end ethernet (100-400Gb) is
> competitive...
> 
> For instance, here's an excellent study of Cray/HP Slingshot (non-COTS):
> https://arxiv.org/pdf/2008.08886.pdf
> (half rtt around 2 us, but this paper has great stuff about congestion,
> etc)
> 
> Yes, someone is sure to say "don't try characterizing all that stuff -
> it's your application's performance that matters!"  Alas, we're a generic
> "any kind of research computing" organization, so there are thousands of
> apps
> across all possible domains.
> 
> Another interesting topic is that nodes are becoming many-core - any
> thoughts?
> 
> Alternatively, are there other places to ask? Reddit or something less
> "greybeard"?
> 
> thanks, mark hahn
> McMaster U / SharcNET / ComputeOntario / DRI Alliance Canada
> 
> PS: the snarky name "NVidiband" just occurred to me; too soon?
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