[Beowulf] experience with HPC running on OpenStack

[m.somers at chem.leidenuniv.nl]

Hi,

i suggest you not only look at the flexibility / complexity regarding
administrating a cluster with OpenStack [there are also many other tools
for that] but also *actually benchmark* with a parallel (threaded) code
you know well and check the strong scaling via Amdhal's law by making some
speedup graphs on VMs and baremetal. You might actually be throwing away a
lot of raw cpu power for *real* HPC codes by doing things on VMs. Serial
on VMs != parallel on VMs: It all depends on your codes and the VM details
now.

https://www.researchgate.net/publication/221565869_Virtual_Machine_Scalability_on_Multi-Core_Processors_Based_Servers_for_Cloud_Computing_Workloads

P.S. in the paper above, the mentioned floating point micro benchmarks are
'trivially parallel': all cores work independently without any
communication and do not share a single bigger workload. This is certainly
not the case for actual HPC codes and these will not show such linearly
perfect scaling neither on VMs, nor on bare metal.

Mark Somers

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mark somers
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