AIX Tip of the Week

Disabling CPU's in AIX 4.3.3

Audience: System Administrators

Date: December 14, 2001

The cpu_deallocate command is useful tool for scaleability testing. This command can be used to dynamically deactivate CPU's. The cpu_deallocate command is significantly easier to use compared to the alternative of shutting the system down and disabling CPU's via the Service Processor.

The command syntax is:

cpu_deallocate <.logical CPU number>.

where "CPU number" is an integer ranging between 0 and "n-1" where "n" is the number of CPU's. (Comment: the logical CPU number is not necessarily the same number associated with proc## in "lsdev -Cc processor" output. The proc## are often not in sequence.)

To verify a processor has been disabled, run

lsattr -El proc##

Although the deactivation is immediate. To reactivate the CPU's, the system must be rebooted.

Prereqs: AIX: Enable cpuguard: chdev -l sys0 - a cpuguard=enable

See AIX Tip Enabling CPU Deallocation for more information.

Bruce Spencer,