Hyperthreading in HPUX

Its a new feature supported in HPUX 11iv3. Its supported only on Integrity system architecture (Itanium duel core processors). Basically after enabling hyperthreading (will be called as HT in this post henceforth) on server, it allows single process to spawn threads on multiple cores at a time. This speed up the processing and in turns enhances performance.

Howto enable it

HT can be enabled at hardware level and also on OS level. While toggling this settings reboot is required for changes to take effect.

Enable/disable HT at hardware level 

There are several ways to do it depends on your server’s environment.

From HPUX OS shell by setting -HT (-m parameter) to on or off in setboot configuration. Also for vpars one can use parmodify command.

Shell

1 2 3 4 5 6 7 8 9

# setboot -m on OR # setboot -m off   # parmodify -T y OR # parmodify -T n

From EFI shell i.e. during boot

Shell

1 2 3 4 5

EFI> cpuconfig threads on OR EFI> cpuconfig threads off

From vPar monitor i.e. vpmon prompt

Shell

1 2 3 4 5

vpmon> threads on OR vpmon> threads off

Enable/disable HT at OS level 

This can be done by setting kernel parameter logical CPU attribute to 1 on 0 in kernel configurations.

Shell

1 2 3 4 5

# kctune lcpu_attr=1 OR # kctune lcpu_attr=0

You need to reboot the system after making these changes so that kernel will boot with HT feature.

SHARE

sangeethakumar

• 
• 
• 
• 
•