HP-UX Virtual Partitions Administrator's Guide (includes A.03.05 and A.04.05)

CPU: CPU Monitor (formerly known as LPMC Monitor)
The CPU Monitor (a part of the diagnostic tool Event Monitor Services (EMS) and not a part of
the vPars Monitor) is designed to Monitor cache parity errors within the CPUs on the system.
With its Dynamic Processor Resilience (DPR), if the CPU Monitor detects a pre-determined
number of errors, the CPU Monitor will deactivate a CPU for the current boot session. If the
problems are severe enough, the CPU Monitor will deconfigure the socket for the next boot of
the system.
Deactivation of a CPU means that the OS will attempt to no longer use the CPU by migrating all
threads off the CPU. Deactivation of a CPU is not persistent across an OS or system reboot.
Deconfiguration of a socket means that the EMS issues a firmware call, marking the socket for
deconfiguration on the next system boot. On the next system boot, none of the cores in the target
socket are visible to either the OS in standalone mode or the OS instances of the virtual partitions.
The deconfiguration is persistent across system boots.
Note here two items:
• a deactivation of a CPU does not mean a deconfiguration of its socket. The CPU Monitor is
able to determine whether the CPU needs to be deactivated or whether it needs to take
further action and deconfigure the socket.
• reboot of a virtual partition is not the same as a reboot of the system (the entire box or
nPartition).
The exceptions to the deactivation of CPUs are the boot processor of each OS instance (the boot
processor has a logical instance of zero) and the last CPU in a cell or nPartition. The exception
to the deconfiguration of sockets is that the last remaining socket will not be deconfigured
(otherwise, the system could not boot).
If any spare iCAP (formerly known as iCOD) or PPU CPUs are available, the necessary number
of CPUs will be activated to replace the CPUs deactivated.
NOTE: On a vPars system, for bound CPUs, the virtual partition boots with the CPU marked
for deconfiguration. For unbound CPUs, the Monitor will attempt to replaced the marked CPUs
with a working CPU; however, if no working CPUs are available, the Monitor automatically
reduces the unbound CPU number for that virtual partition in the vPars database and allows
the virtual partition to boot with the working CPUs.
Dual-core processors have two CPUs (that is, cores) per processor. Deactivation happens on a
CPU level, but deconfiguration happens at the socket level. If a processor’s socket is deconfigured,
both CPUs sharing the socket will be unavailable.
258 CPU, Memory, and I/O Resources (A.03.xx)