cpuonoff -- activate, inactivate or display processor state


cpuonoff [ -c ] [ -a cpu ] [ -d cpu ] [ -i cpu ]


cpuonoff is a utility which allows processors to be activated or inactivated without the need to reconfigure the kernel. A processor that has been inactivated will not run any processes but is still capable of processing interrupts. cpuonoff will also display the current state of each processor.

cpuonoff will not allow the base processor, CPU1, to be made inactive.

root permission is required to run cpuonoff.

The options are as follows:

displays the current state of all processors in the form: cpu 1: active/inactive
cpu n: active/inactive

-a cpu
activates cpu where cpu is an integer

-d cpu
inactivates cpu where cpu is an integer

-i cpu
inactivates cpu where cpu is an integer

Exit values

cpuonoff exits with 0 upon successful completion. It exits with 1 if an error occurs.


Messages may include the following:

cpuonoff: invalid CPU specified

The argument specifying a processor must be numeric.

cpuonoff: cannot specify negative CPU

The argument specifying a processor must be a positive integer.

cpuonoff: CPU specified exceeds number of CPUs installed

The specified processor does not exist or has not been serialized.

cpuonoff: can't open device

The required device node device is missing. Run idmknod(ADM) to recreate any missing device nodes.

cpuonoff: cannot determine number of processors

The kernel cannot determine the number of processors installed and serialized.

cpuonoff: malloc for procdata failed

cpuonoff could not malloc required memory for its internal work area.

cpuonoff: cannot determine processor_data

cpuonoff could not read the relevant processor data from the kernel.

cpuonoff: incorrect option usage

Options given to cpuonoff must be one of -a, -i or -c.

cpuonoff: cannot modify state of CPU 1

The state of the base processor cannot be modified. It always remains in the active state.

cpuonoff: cannot inactivate CPUnum

cpuonoff failed to inactivate the specified processor, number num.

cpuonoff: cannot activate CPUnum

cpuonoff failed to activate the specified processor, number num.


This command numbers processors beginning with 1. The similar psrinfo(ADM) and psradm(ADM) commands number processors beginning with 0. The two sets of commands can be used together, but be aware of the numbering sequence difference.

If a processor running processes locked onto it is made inactive, then the locked processes will be suspended until the processor is once again activated.



See also

cpu(HW), cpusar(ADM), mpstat(ADM)

Standards conformance

cpuonoff is not part of any currently supported standard; it is an extension of AT&T System V provided by the Santa Cruz Operation, Inc.
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 -- 03 June 2005