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	A new command line utility, bindintcpu, has been released in 
AIX 4.3.2 APAR# IX983061. This utility provides system administrators
capabilities to direct interrupts from a specific hardware device
to certain CPU(s) only. Normally, hardware device interrupts can be 
delivered to any running CPU, and the distribution is determined by
some pre-defined methods, for example, round-robin through all of the
CPUs. This utility lets system administrators bypass the pre-defined
method and control the interrupts distribution in order to fine tune
their MP system performance. Please note that this utility is applicable 
only on selective hardware types. 

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bindintcpu Command

Purpose

Assign a bus interrupt level to be delivered only to the indicated CPU(s).

Syntax

	bindintcpu <level> <cpu> [<cpu>...]
	bindintcpu -q <level>
	bindintcpu -u <level>

Description

This utility provides system administrators capabilities to direct 
interrupts from a specific hardware device at the specified bus interrupt 
level - <level> - to a specific CPU, or to a set of CPU(s), specified
by the CPU # in <cpu>. Normally, on a multiple CPU system, hardware 
device interrupts can be delivered to any running CPU, and the distribution 
among all of the CPU(s) is determined by some pre-defined methods, for 
example, round-robin through all of the CPUs, etc. This utility lets 
system administrators bypass the pre-defined method and control the 
interrupts distribution from a specific device to selected CPU(s) only.
This utility is applicable only on selective hardware types.

If an interrupt level has been bound with certain CPU(s), all interrupts
coming from that level will be distributed only to specified CPU(s) until
it is re-directed by this command again. However, interrupts bound to CPU0 
cannot be re-directed again. If an interrupt level has been bound with CPU0, 
it will stay on CPU0 until system reboot.
 
If the -q flag is used, this utility will instead list which CPU(s) the
interrupt <level> is bound to. If the specified interrupt <level>  is not
currently bound, bindintcpu -q <level> produces no output. With the -u flag, an
administrator can unbind a specified interrupt from its CPU(s), and that
interrupt will once again be delivered to any running CPU through some
pre-defined methods.

Please note that not all of the hardware models support one-to-many
bindings, i.e., specifying multiple CPUs with this command will always
result in errors on certain types of machines. For consistency, it is 
recommanded to specify one CPU per "bindintcpu" command whenever is possible.
On some platforms, the -q and -u flags are also unsupported.

Examples

  1. To direct all the interrupts from bus interrupt level 6 to CPU1:

		bindintcpu 6 1

  2. To direct all the interrupts from bus interrupt level 6 to CPU2 and 
     CPU3:

		bindintcpu 6 2 3

Files

/usr/sbin/bindintcpu	contains the bindintcpu command

Related Informantion