Playing a bit with psradm

I just found psradm command in Solaris 10. This command is a utility to change operational status of processors. The legal states for processor are on-line, off-line, spare, faulted, and no-intr.

An on-line processor processes LWPs (lightweight processes) and can be interrupted by I/O devices in the system.

An off-line processor does not process any LWPs. Ussualy, an off-line processor is not interuptable by I/O devices in the system. On some processors or under certain conditions, it might not be possible to disable interupts for an off-line processor. Thus, the actual effect of being off-line might vary from machine to machine.

A spare processor does not process any LWPs. A spare processor can be brought on-line, off-line or to no-intr by a privileged user of the system or by the kernel in response to changes in the system state.

A faulted processor is identified by the kernel, which monitors the behaviour of processor over time. A privileged user can set the state of a faulted processor to be on-line, off-line or to no-intr, but must use the force option to do so.

A no-intr processor processes LWPs but is not interruptible by I/O devices.

For web application-like hosted in UltraSparc T1 processor, it is better to make main thread on each core in the chip become no-intr state by issuing psradm -i command on processor id 0, 4, 8, 12, 16, 20, 24, 28 (example for 8 cores chip), so at least there is 8 processes is non-interruptable.

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