Windows 2000 Terminal Server performance degraded when running under ESXi 5.0

Products

• VMware vSphere ESXi

Issue/Introduction

The issue of Windows 2000 Terminal Server performance degradation when running under ESXi 5.0 is resolved in ESXi 5.0 Update 1.

Symptoms:

• Windows 2000 Terminal Server shows degraded performance when running under ESXi 5.0.
• Performance Charts for the virtual machine show a much higher CPU usage compared to the same virtual machine running on vSphere ESXi/ESX 4.x.
• The Windows guest operating system task manager shows a very high CPU usage as soon as multiple Terminal Server users are connected.
• The guest operating system appears to intermittently become unresponsive due to the CPU load. A CPU spike for the System process may occur.
• Changing the virtual machine's hardware to version 8 or increasing the vCPU count does not resolve the issue.
• After migrating the virtual machine back to a host running ESXi/ESX 4.x, the virtual machine returns to normal behavior.

Environment

VMware vSphere ESXi 5.0

Cause

This issue occurs due to changes to the Binary Translation (BT) Monitor Mode of the VMware Hypervisor in version 5.0. These changes were included to address an issue related to coherency of translated code.

Resolution

This issue is resolved in ESXi 5.0 Update 1. For more information, see the Resolved Issues section in the VMware ESXi 5.0 Update 1 Release Notes.

To work around this issue on the previous versions of ESXi 5.0, perform one of these options:

• Migrate the virtual machine back to an ESXi/ESX 4.x host.
  
  This option is only possible if the virtual machine is still using Virtual Hardware Version 7 or lower. If the Virtual Hardware Version has already been upgraded to 8, you can use VMware Converter Standalone to downgrade the Hardware Version. For more information, see the VMware vCenter Converter Standalone User's Guide.
  
  
• Manually change the Monitor Mode of the virtual machine from Binary Translation (BT) Monitor Mode (Automatic for Windows 2000 virtual machines) to use:
  
  
  • Intel VT-X/AMD-V for instruction set virtualization and software for MMU virtualization (HV)
    
    or
    
    
  • Intel VT-X/AMD-V for instruction set virtualization and Intel EPT/AMD RVI for MMU virtualization (HWMMU)
  
  To change the virtual machine monitor mode:
  
  Note: The virtual machine can either be powered on or off while performing this procedure.
  
  
  1. Log into the VMware vSphere Client.
  2. In the virtual machine inventory, right-click the virtual machine and click Edit Settings. The Virtual Machine Properties dialog appears.
  3. Click the Options tab.
  4. Click CPU/MMU Virtualization under Advanced, and choose an instruction set:
     
     
     • Automatic
     • Use software for instruction set and MMU virtualization
     • Use Intel VT-X/AMD-V for instruction set virtualization and software for MMU virtualization
     • Use Intel VT-X/AMD-V for instruction set virtualization and Intel EPT/AMD RVI for MMU virtualization
       
       
     The appropriate option depends on the features provided by your CPU. To identify which features your CPU is capable of, check MONITOR MODE: allowed modes in the virtual machine's vmware.log (in the virtual machine folder on the datastore). For example:
     
     2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: allowed modes : BT HV HWMMU
     2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: user requested modes : BT HV HWMMU
     2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: guestOS preferred modes: BT HWMMU HV
     2011-11-21T10:14:07.154Z| vmx| MONITOR MODE: filtered list : BT HWMMU HV
     
     Where:
     
     • allowed modes refers the mode your hardware is capable of
     • user requested modes refers to the setting defined in the virtual machine configuration
     • guestOS preferred modes refers to the default values for the selected guest operating system
     • filtered list refers to the actual monitor mode used by the Hypervisor (in order of appearance)
     
     For information on changing the Monitor Mode, see Changing the virtual machine monitor mode (1036775).

Additional Information

For more information about the different Monitor Modes, see:

• Software and Hardware Techniques for x86 Virtualization
• Performance aspects of x86 virtualization.

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Changing the virtual machine monitor mode