To increase performance, you can select how the virtual CPUs of a virtual machine share physical cores on a hyperthreaded system.

Before you begin

  • The hyperthreaded core sharing option must be enabled in your system's BIOS settings. See the vSphere Resource Management documentation.

  • Turn off the virtual machine.

About this task

Hyperthreading technology allows a single physical processor to behave like two logical processors. The hyperthreaded core sharing option provides detailed control over whether to schedule a virtual machine to share a physical processor core. The processor can run two independent applications at the same time. Although hyperthreading does not double the performance of a system, it can increase performance by better utilizing idle resources.

ESXi generally manages processor scheduling well, even when hyperthreading is enabled. These settings are useful only for fine-tuning critical virtual machines.

Note:

Hyperthreaded core sharing is only supported for ESXi hosts version 5.0 and earlier.

Procedure

  1. Right-click a virtual machine in the inventory and select Edit Settings.
  2. On the Virtual Hardware tab, expand CPU, and select a sharing mode from the HT Sharing drop-down menu.

    Option

    Description

    Any (default)

    The virtual CPUs of this virtual machine can share cores with other virtual CPUs of this or other virtual machines.

    None

    The virtual CPUs of this virtual machine have exclusive use of a processor core whenever they are scheduled to it. The other hyperthread of the core is halted while this virtual machine is using the core.

  3. Click OK.