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I was wondering whether the following scenario is possible with current virtualization technologies, such as Xen and VMware: - One physical host with 1 CPU with 8 cores, 2 logical processors (threads) per core (hyperthreating enabled) is virtualized, so that 16 virtual machines (VMs) with one vCPU each are created.

For each VM, is it possible to set P-States to its vCPU (of course the max frequency will be that of the physical processor - and thus that of the core and thus that of the logical processor), independently of the other VMs, even though they are hosted on the same physical machine?

In other words, do current virtualization technologies support DVFS per vCPU (with different P-States per vCPU), where all vCPUs are provisioned on the same host?

For example, can we reduce the frequency of the vCPU of VM1 from 1.5GHz to 1GHz, but the other 15 VMs continue to operate at 1.5GHz, where 1.5GHz is the maximum frequency of the physical processor (and thus core and thus logical processor)?

I would greatly appreciate it if you could answer the above question, since I've been searching the internet for a while and I couldn't get a clear answer.

Many thanks in advance for your time.

  • Not likely... why do you want to do this anyway? You can restrict the VMs CPU time / weighting, which may have a similar effect. – Attie Mar 11 '18 at 16:26
  • Don't see it working on a per thread basis like you want, but possibly a per VM. VirtualBox allows you to set the "execution cap" fir a VM from 1 to 100%, where the percentage is based on CPU usage. From VirtualBox... "This setting limits the amount of time a host CPU spends to emulate a virtual CPU. The default setting is 100% meaning that there is no limitation. A setting of 50% implies a single virtual CPU can use up to 50% of a single host CPU." Note, that you won't see your host 2GHz CPU show up as a 1GHz CPU if you set the execution cap to 50%. – essjae Mar 13 '18 at 21:18

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