6.0

Configuring Advanced CPU Scheduling Settings
You can select CPU options that involve scheduling the virtual machine processing to physical processor
cores and hyperthreads. ESXi generally manages processor scheduling well, even when hyperthreading is
enabled. These settings are useful only for detailed tweaking of critical virtual machines.
Configure Hyperthreaded Core Sharing in the vSphere Client
You can select how the virtual CPUs of a virtual machine share physical cores on a hyperthreaded system.
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.
Prerequisites
n
The hyperthreaded core sharing option must be enabled in your system's BIOS settings. For more
information, see the Resource Management documentation.
n
Power off the virtual machine.
Procedure
1 In the vSphere Client inventory, right-click the virtual machine and select Edit Settings.
2 Click the Resources tab and select Advanced CPU.
3 Select a mode from the Hyperthreading Sharing Mode 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.
Internal
On a virtual machine with exactly two virtual processors, the two virtual
processors are allowed to share one physical core (at the discretion of the
host scheduler), but this virtual machine never shares a core with any
other virtual machine. If this virtual machine has any other number of
processors other than two, this setting is the same as the None setting.
4 Click OK to save your changes.
Configure Processor Scheduling Affinity in the vSphere Client
The Scheduling Affinity option gives you detailed control over how virtual machine CPUs are distributed
across the host's physical cores (and hyperthreads if hyperthreading is enabled). This panel does not appear
for virtual machines in a DRS cluster or when the host has only one processor core and no hyperthreading.
Using CPU affinity, you can assign a virtual machine to a specific processor. This assignment allows you to
restrict the assignment of virtual machines to a specific available processor in multiprocessor systems.
For potential issues with CPU affinity, see the Resource Management documentation.
Prerequisites
Power off the virtual machine.
Chapter 15 Configuring Virtual Machines in the vSphere Client
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