HP-UX Virtual Partitions Administrator Guide (includes A.05.08) (5900-1312, March 2011)

Hyperthreading is supported within vPars A.05.xx environments. However, note the following
details.
• HT ON/OFF can be set using any of the following commands.
The vPar Monitor’s threads command.
The syntax is:
◦
threads [on|off]
For example:
MON> threads
HyperThreading is currently OFF
HyperThreading will be OFF after the next nPar reboot
MON> threads on
HyperThreading is now set to be ON after the next reboot
MON> threads
HyperThreading is currently OFF
HyperThreading will be ON after the next nPar reboot
MON> threads off
HyperThreading is now set to be OFF after the next reboot
◦ The EFI shell’s cpuconfig command.
The syntax is:
cpuconfig threads [on|off]
For a primer on cpuconfig, see “Setting Hyperthreading (HT ON/OFF) and cpuconfig
Primer” (page 247).
◦ The HP-UX shell’s parmodify command.
The syntax is:
parmodify -T y|n
◦ The HP-UX shell’s setboot command.
The syntax is:
setboot -m on|off
For more information on using or setting HT ON/OFF, see the nPartition Administrator's Guide.
• Although hyperthreading is supported within vPars, CPU assignments to virtual partitions
remain on a per-core basis and not on a logical CPU (LCPU) basis.
This means that all the vPars commands for CPUs work the same as they did in vPars A.04.xx,
including using the same legacy hardware path format.
• HT ON is not supported in a mixed HP-UX 11i v2/v3 vPars environment or mixed HP-UX 11i
v1/v2/v3 vPars environment.
• Turning hyperthreading on or off at the EFI level or vPars Monitor level has nPar wide scope.
Individual virtual partitions can use the HP-UX command lcpu_attr to turn logical processors
on or off within processor sets in a virtual partition. However, if hyperthreading is turned off
at the EFI or vPars Monitor level, the lcpu_attr command will not have any effect.
CPUs: Managing I/O Interrupts
This section describes information you need if you are managing I/O interrupts on a vPars-enabled
system. Note that migrating interrupts should only be done by advanced administrators for
performance tuning.
CPUs: Managing I/O Interrupts 199