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stormshift / support

This repo should serve as a central source for reporting issues with stormshift
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Disable HyperThreading on ISAR BM Nodes #178

Open DanielFroehlich opened 3 months ago

DanielFroehlich commented 3 months ago

Currently, ISAR Bare Metal Nodes have Hyperthreading enabled. Thats a bit dangerous, because we feel like "unlimited" CPU capacity with reported 448 vCPUs. But actually, system will become slower when 50% CPU utilisation is reached. Hyperthreading does not double the capacity. Best case only by a factor of 10-30%, depending on the workload. And maybe even not at all. Which means: a system that reports 50% utilisation is actually way more utilised then it looks like. And it starts to become slower.

We are starting to see 50% utili on individual nodes of ISAR: image (e..g ucs57).

In stormshift RHV, I did disable Hyperthreading to avoid this pitfall and always have maximum performance.

Lets discuss!

rbo commented 3 months ago

I will provide a machine config pool where we can disable hyperthreading via kernel arg. Then we can easily switch back and forth for testing purposes.