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We are creating virtual os threads inside guest os but the actual physical core is on the host machine. Will hyperthread = true in guest VM config make any difference?

I can visualize how hyperthreading works on the host as it has a physical core, but VM has virtualized os threads so it hard for me to visualize hyperthreading inside a VM.

Can someone please explain to me how it will be useful.

Karthik Nedunchezhiyan
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  • HT support just means detecting when 2 cores share some resources (other than just memory bandwidth) and scheduling accordingly. A good hypervisor should make this visible to a guest so it can tell which of its cores share a physical core or not. The only time HT isn't useful is when running a workload that can saturate the front-end of a physical core with one thread (high IPC code), or where cache misses from competing for cache cause more than a factor of 2 slowdown. (Or where you need low latency more than high throughput.) – Peter Cordes Mar 06 '20 at 05:14
  • @PeterCordes tnx for your response, it is bit hard for me to understand this. can you please explain this with a example. – Karthik Nedunchezhiyan Mar 06 '20 at 06:51

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