Virtual Hyperthreading is supported from vSphere 8 Virtual Hyperthreding support for VMs. In VIO 7.3, user can create instances with vHT enablement.

Prerequisites

  • vSphere 8 is required.
  • HW version VMX 20 is required.
  • Threads per core is set to 2 in vSphere 8.

Procedure

  1. Create instance with vHT enablement with Openstack CLI.
    1. Create a flavor with vHT property set. 
      openstack flavor create --vcpus 2 --ram 512 --disk 1 m1.tiny.ht
openstack flavor set m1.tiny.ht --property vmware:latency_sensitivity_level="high with HT"
    2. Create nova instance with above flavor.
  2. User can also create instances with vHT enablement in horizon UI.
    1. Create flavor in Admin->Flavors. The VCPU number should be even number.
    2. Update metadata, setting vmware:latency_sensitivity_level to "high with HT".
    3. Create instance with the above flavor.

Results

User can check the VMX file and view the following options: 
cpuid.numSMT=2
sched.cpu.latencySensitivity="high"
virtualHW.version=20

Or, user can check VM settings in vCenter and ensure that Latency Sensitivity is set to High with Hyperthreading.

CPU will reserve 50% of the total CPU frequency and 100% of the memory by default. It is not suggested to set quota:cpu_reservation_percent or quota:cpu_reservation in the flavor together with vmware:latency_sensitivity_level="high with HT". User should use the default value, which is 50%.