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nPartition Administrator's Guide > Chapter 7 Managing Hardware Resources

Enabling and Disabling Hyper-Threading on Dual-Core Intel Itanium 2 Processors

 

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nPartitions with dual-core Intel Itanium 2 processors support Hyper-Threading. Hyper-Threading provides the ability for processors to create a second logical CPU on a single core that can allow additional efficiencies of processing. For example, a dual-core processor with Hyper-Threading active provides four logical processors, two on each processor core.

CAUTION: Some operating systems do not support Hyper-Threading. Problems can occur when running an OS that does not support Hyper-Threading on an nPartition that has Hyper-Threading enabled.
NOTE: You must reset an nPartition when changing its Hyper-Threading status. Hyper-Threading will not be enabled or disabled until after the nPartition is reset.

Checking the Hyper-Threading Status for an nPartition. To check the current Hyper-Threading status for an nPartition:

  • From the EFI Shell: cpuconfig or cpuconfig threads

  • From HP-UX: setboot

  • Using the Enhanced nPartition Commands: parstatus -T

Example 7-2 Checking the Hyper-Threading Status for an nPartition

# setboot Primary bootpath : 0/0/1/1/0.12.0 HA Alternate bootpath : 0/0/0/1/0 Alternate bootpath : 0/0/0/1/1 Autoboot is ON (enabled) Hyperthreading : ON 1 : OFF (next boot) 2 #
1

The HP-UX setboot command indicates that Hyper-Threading currently is enabled (ON) for the nPartition.

2

The next time the nPartition is booted (after it is reset), Hyper-Threading will be disabled (OFF) for the nPartition.

Enabling Hyper-Threading for an nPartition. To enable Hyper-Threading, use any of the following methods and then reset the nPartition whose Hyper-Threading status you have changed:

  • From the EFI Shell: cpuconfig threads on

  • From HP-UX: setboot -m on

  • Using the Enhanced nPartition Commands: parmodify -pn -T y, where n is the nPartition number.

  • Using Partition Manager: Perform the Modify nPartition task and select the Enable Hyper-Threading check box on the Configure Memory tab.

You must reset an nPartition after changing its Hyper-Threading status.

Example 7-3 Enabling Hyper-Threading for an nPartition

Shell> cpuconfig threads 1 cpuconfig: Threads are turned off. Shell> Shell> cpuconfig threads on 2 cpuconfig: Threads will be on after a reset. Shell>
1

The EFI Shell cpuconfig threads command indicates that Hyper-Threading currently is disabled (turned off) for the nPartition.

2

This EFI Shell command configures Hyper-Threading to be enable after the nPartition is reset.

Disabling Hyper-Threading for an nPartition. To disable Hyper-Threading, use any of the following methods and then reset the nPartition whose Hyper-Threading status you have changed:

  • From the EFI Shell: cpuconfig threads off

  • From HP-UX: setboot -m off

  • Using the Enhanced nPartition Commands: parmodify -pn -T n, where n is the nPartition number.

  • Using Partition Manager: Perform the Modify nPartition task and deselect the Enable Hyper-Threading check box on the Configure Memory tab.

You must reset an nPartition after changing its Hyper-Threading status.

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