In multiprocessor environments, Sun Solaris can allow enabling or disabling Processors. This although is not something that we would do all the time but can come handy when troubleshooting hardware issues.
Sun Solaris has the psradm utility which allows enabling or disabling a Processor on the system. The psradm utility changes the operational status of processors. The legal states for the processor are on-line, offline, spare, Faulted, and no-intr. An online processor processes LWPs (lightweight processes) and can be interrupted by I/O devices in the system.
To enable or disable a processor on the system we need to know the Processor ID. This can be found using the psrinfo utility as follows:
0 on-line since 05/09/2008 19:41:32
where 0 is the processor ID.
To know the path of the psradm command
sunsolaris# which psradm
To disable a processor
sunsolaris# psradm -f 0
where ‘0’ is the processor ID and ‘-f’ indicates the processor is taken offline (disable)
To enable a processor
sunsolaris# psradm -n 0
where ‘0’ is the processor ID and ‘-n’ indicates the processor is brought online (enable)