psradm, offline, online - Stops and starts processors in a multiprocessor
/usr/sbin/psradm -f [-v] [[-a] [processor_id...]]
/usr/sbin/psradm -n [-v] [[-a] [processor_id...]]
/usr/sbin/online [-v] [processor_id...]
/usr/sbin/offline [-v] [processor_id...]
The following options apply only to the psradm command:
-a Specifies that all the processors except the master processor be put
off line or on line.
-f Puts the specified processor off line.
-n Puts the specified processor on line.
The following option applies to all forms of the command:
-v Displays a message about the status of the operation performed on each
On a multiprocessor system, the psradm command puts one or more processors
off line (stops a processor) or on line (starts a processor).
The processor_id variable specifies an integer that uniquely identifies a
processor. Use the psrinfo command to display processor identification
The offline command puts one or more processors off line (stops a proces-
sor). If no processors are specified, all processors that are on line are
stopped except the master processor.
The online command puts one or more processors on line (starts a proces-
sor). If no processors are specified, all processors that are off line are
You must be the root user to use this command.
The /var/adm/wtmp file contains information about successful processor
Do not use the psradm command to disable CPUs when benchmarking perfor-
mance, because the command does not provide an accurate reflection of the
performance of a system that actually has fewer CPUs. Accurate performance
results are obtained only when you disable the CPUs at the SRM console com-
On platforms that do not support primary processor reassignment, you cannot
use the off line command options to stop the boot processor in a multipro-
Each quad building block (QBB) on a AlphaServer GS-series system assigns
one processor to take interrupts for that QBB. If you attempt to take this
processor off line, the following error is displayed:
offline: processor N: Invalid argument
An interrupt-handling processor has an identifier number (N) that is evenly
divisibe by 4. At present, there is no method of migrating interrupts to
another processor, therefore, you cannot take this processor off line.
1. The following command puts processors 2 and 3 off line:
# psradm -f 2 3
2. The following command puts all the processors on line:
# psradm -n -a
3. The following command puts all processors on line:
# online -v
Commands: pset_info(1), psrinfo(1)