HP-UX Reference (11i v2 07/12) - 1M System Administration Commands A-M (vol 3)

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intctl(1M) intctl(1M)
a similar average weight from the interrupt load perspective.
• round_robin
Another supported algorithm is round_robin , which assigns interrupts to the available CPUs in a
round robin fashion. This is similar to the HP-UX default boot time interrupt distribution method, but
the interrupt assignments may differ because of the difference in the way I/O cards and CPUs are
discovered.
driver_weight
is a better choice of algorithm for systems having I/O cards that demand largely vary-
ing range of interrupt processing needs. Hence
driver_weight is chosen as the default algorithm. In
systems where all I/O cards demand similar interrupt processing capacity or when it becomes difficult to
determine interrupt load generated by each driver, then the
round_robin algorithm can be used.
Administrators can also configure automatic balancing of interrupts at periodic intervals. Balancing will be
performed only if there is an interrupt distribution imbalance. This is desirable in a dynamic CPU migra-
tion environment such as WLM (Work load Manager). Refer to intrbald(1M) for more details.
Several settings are provided for managing balancing of interrupts. This information can be provided using
the command line options or can be persistently configured in the configuration file
/etc/intctl.conf, see the Interrupt Configuration File section below.
Options
By default, the command displays interrupt information about all the interface cards on the system.
intctl recognizes the following options:
-a algorithm Balancing of interrupts may be performed any time during system up time to reduce CPU
overload because of interrupt handling. Users have several options to control balancing of
interrupts.
There are two algorithms supported to balance interrupt distribution.
• Driver weight (-a driver_weight
) based approach.
This is the default algorithm used to balance interrupts when no algorithm is specified.
The default can be set by changing
INTCTL_DEFAULT_ALGO
in the configuration file
/etc/intctl.conf.
Each driver is given a weight based on the number of interrupts it may generate.
Balancing operations ensure that each CPU is loaded (from interrupt load perspective)
with a comparable total driver weight. These weights can be between
0 and INT_MAX
(see limits(5)). Most of the HP-UX drivers are already defined in the configuration file
section INTCTL_DRIVER_WEIGHTS
. Users can modify or override these driver
weights, but they should make sure not to set unrealistic driver weights without know-
ing the amount of interrupt load the driver could generate.
• Round robin (
-a round_robin ) approach.
Each interrupt in the system will be assigned an available CPU in round robin fashion.
This balancing approach can be used when it becomes difficult to differentiate drivers
based on their interrupt load. Compared to the driver weight based approach, round
robin could result in more interrupt migrations while balancing interrupts.
-b Balance the interrupt distribution of the system by performing the least number of migra-
tions that will distribute interrupt load across a specified set of CPUs.
-c cpu_id By itself (without any other options), display interrupt information about the specified
CPU.
When used with the -M option, -c cpu_id specifies the CPU ID of the CPU to which the
interrupt is to be moved.
-C class Display interrupt information about all the interface cards belonging to the specified class.
Can be used with the -H hw_path option to display interrupt information about the inter-
face card under the hw_path that belongs to the specified class.
-F Produce a compact listing of fields separated by colons.
-h Display the usage of the command.
402 Hewlett-Packard Company − 2 − HP-UX 11i Version 2: December 2007 Update