Installing and Managing HP-UX Virtual Partitions (includes A.03.03)

CPU, Memory, and IO Resources
Managing IO Interrupts (vPars A.04, A.03 and earlier)
Chapter 6
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Managing IO Interrupts
(vPars A.04, A.03 and earlier)
This section described information you need if you are managing IO interrupts on a vPars-enabled system.
Note that migrating interrupts should only be done by advance administrators for performance tuning.
intctl command
The intctl command is a HP-UX tool that allows you to manage IO interrupts among active processors.
For HP-UX 11i v1, intctl is not installed by default with HP-UX, but you can obtain the software for intctl
from the HP-UX Software Pack for 11i v1. Software Pack is available from the Software Pack DVD included
with the HP-UX 11i OE DVDs or from the Software Depot web site at http://www.hp.com/go/softwaredepot.
For HP-UX 11i v2, the software for intctl is part of the Core OS.
For more information, see the Interrupt Migration Product Note available at http://docs.hp.com or the intctl
(1M) manpage.
A.04
• At boot time of a virtual partition, interrupts are processed by all the CPUs in the virtual partition.
• After boot, CPUs that are added to the virtual partition are not assigned to process IO interrupts.
However, you can migrate IO interrupts to any added CPU using intctl.
• After boot, CPUs that are deleted from a virtual partition no longer process IO interrupts for the
partition. When a CPU is deleted from a virtual partition, if the deleted CPU has IO interrupts, the IO
interrupts are automatically and transparently reassigned to other active CPUs in the partition.
NOTE Repeatedly adding and deleting CPUs without a reboot of the target virtual partition may
cause an imbalance in the interrupt processing load across the CPUs of the virtual partition.
However, you can use intctl if the imbalance is not desired.
A.03 and earlier
• Interrupts are processed only by bound CPUs.
• Therefore, when managing IO interrupts with intctl, you can manage the IO interrupts only among the
bound CPUs.
• Further, disabling interrupts on a bound CPU does not convert the bound CPU into an unbound CPU.