CPU Conditions as the Result
of a LPMC Error in a vPar Environment
Version 2.0 10/13/02
This white paper provides an explanation of what happens to the state of a CPU in both a non Virtual Partitions (vPars) environment and a vPar environment. It is meant to convey a basic understanding of what happens to a CPU if LPMC errors are d 11211c28l etected specifically in a vPars environment. Please see the white paper on Dynamic Processor Deallocation And Dynamic Processor Resilience for the details on the actual process of deallocation and deconfiguration.
Possible CPU states: Assigned Bound, assigned Floating, and unassigned Floating (which can be used in iCOD systems).
The Monarch CPU in a vPar will always be a Bound CPU.
The CPU with a logical ID of zero is always the monarch.
With iCOD and vPars, the LPMC monitor does not automatically replace a failed CPU by assigning a new Floating CPU to the vPar; this must be done manually.
Deallocation and Deactivation are synonyms and refer to a CPU that is still recognized by an OS, but is not actively scheduling processes; such a CPU may still handle I/O interrupts.
Deconfigured refers to CPUs that are disabled by firmware when the system/nPar reboots; such CPUs are not visible to the OS or vPar monitor.
Non-vPar environment
The LPMC Monitor will make a call to deallocate and a call to mark-for-deconfiguration the CPU in question, when the LPMC error threshold has been exceeded
For monarch CPUs, the mark for deconfiguration will occur, but not the deallocation.
For non-monarch CPUs, the mark for deconfiguration will occur AND the deallocation will occur.
In either case, the CPU is NOT completely taken out of USE until the system/partition is rebooted.
vPar Environment
On a system with vPars, the behavior for the Bound Monarch CPU is the same as in a non-vPars environment. Each vPar has only ONE Monarch CPU that is one of the Bound CPUs (i.e. a vPar can have more than one Bound CPU). If the LPMC error threshold has been exceeded on the Bound Monarch CPU, the LPMC Monitor will make a call to mark-for-deconfiguration. The LPMC Monitor will not attempt to deallocate this Monarch CPU. Upon vPar OS reboot, the Bound Monarch CPU will reappear in the vPar as an active CPU (however it is still marked for deconfiguration). Upon vPar Monitor reboot (i.e. reboot of the hard partition), PDC will deconfigure the Bound Monarch CPU and the vPar Monitor will no longer see it.
A Bound NON-Monarch CPU behaves the same EXCEPT that it CAN be deallocated. It is marked for deconfiguration and also deallocated. However upon vPar OS reboot, again, this Bound NON-Monarch CPU is put back in use and will reappear in the vPar and will be an active CPU (however it is still marked for deconfiguration). Upon vPar Monitor reboot (i.e. reboot of the hard partition), PDC will deconfigure the Bound NON-Monarch CPU and the vPar Monitor will no longer see it.
Floating CPUs behave a bit differently. If the LPMC error threshold has been exceeded, the LPMC Monitor will make a call to deallocate and a call to mark-for-deconfiguration the Floating CPU. It is then deallocated and marked for deconfiguration. Upon vPar reboot, this Floating CPU is NOT put back in use and will NOT reappear in the vPar and it is still marked for deconfiguration. Upon vPar Monitor reboot (i.e. reboot of the hard partition), PDC will deconfigure the Floating CPU and the vPar monitor will no longer see it.
In a NON-vPars environment, a marked Monarch CPU will be deconfigured during a reboot. The PDC will assign another CPU to be the Monarch and the system will boot.
In a vPars environment, CPUs can be specified by min/max numbers or by hardware paths. If a CPU is specified via min/max specification, and the CPU is no longer available to the vPars Monitor (deconfigured), the vPars Monitor will attempt to meet the min (Bound) CPU count, even if it needs to remove CPUs from the pool of available Floating CPUs. The vPar Monitor will do this until it has no more Floating CPUs.
If a CPU is specified via hardware path, and the CPU is no longer available to the vPars Monitor (deconfigured), the vPars Monitor will again attempt to replace the CPU with one of the available Floating CPUs. The vPar Monitor makes several passes to meet the CPU requirements and whether the CPUs are specified by min/max or hardware path, the vPar Monitor will allocate CPUs.
At this time there is no advantage to specifying CPUs by hardware path.
Bound Monarch CPUs are marked-for-deconfiguration but not deallocated or taken out of the system (deconfigured) until the vPar Monitor (i.e. system/nPar) is rebooted. These CPUs will reappear as active CPUs if ONLY the vPars OS is rebooted, and not the vPar Monitor.
Bound NON-Monarch CPUs are marked-for-deconfiguation AND deallocated but not deconfigured from a vPar until the vPar Monitor is rebooted. These CPUs will reappear as active CPUs if ONLY the vPars OS is rebooted, and not the vPar Monitor.
Floating CPUs are marked-for-deconfiguration AND deallocated. These CPUs will NOT be reassigned to a vPar when the vPars OS is rebooted. And a system/nPar reboot or vPar Montitor reboot will deconfigure the Floating CPU and the vPar monitor will no longer see it.
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