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  3. irqbalance
  4. irqbalance(1)

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IRQBALANCE(1) irqbalance IRQBALANCE(1)

NAME

irqbalance - distribute hardware interrupts across processors on a multiprocessor system

SYNOPSIS

irqbalance

DESCRIPTION

The purpose of irqbalance is distribute hardware interrupts across processors on a multiprocessor system in order to increase performance.

OPTIONS

Causes irqbalance to be run once, after which the daemon exits
Causes irqbalance to print extra debug information. Implies --foreground

Causes irqbalance to run in the foreground (without --debug)

Set the policy for how irq kernel affinity hinting is treated. Can be one of:

exact irq affinity hint is applied unilaterally and never violated

subset irq is balanced, but the assigned object will be a subset of the affintiy hint

ignore irq affinity hint value is completely ignored

The default value for hintpolicy is ignore

Set the threshold at which we attempt to move a cpu into powersave mode If more than <threshold> cpus are more than 1 standard deviation below the average cpu softirq workload, and no cpus are more than 1 standard deviation above (and have more than 1 irq assigned to them), attempt to place 1 cpu in powersave mode. In powersave mode, a cpu will not have any irqs balanced to it, in an effort to prevent that cpu from waking up without need.

Add the specified irq to the set of banned irqs. irqbalance will not affect the affinity of any irqs on the banned list, allowing them to be specified manually. This option is addative and can be specified multiple times. For example to ban irqs 43 and 44 from balancing, use the following command line: irqbalance --banirq=43 --banirq=44

This allows a user to specify the cache level at which irqbalance partitions cache domains. Specifying a deeper cache may allow a greater degree of flexibility for irqbalance to assign irq affinity to achieve greater performance increases, but setting a cache depth too large on some systems (specifically where all cpus on a system share the deepest cache lavel), will cause irqbalance to see balancing as unnesessecary. irqbalance --deepestcache=2

The default value for deepestcache is 2.

Execute the specified script for each irq that is discovered, passing the sysfs path to the associated device as the first argument, and the irq vector as the second. An exit value of 0 tells irqbalance that this interrupt should balanced and managed as a normal irq, while a non-zero exit code indicates this irq should be ignored by irqbalance completely (see --banirq above). Use of this script provides users the ability to dynamically select which irqs get exluded from balancing, and provides an opportunity for manual affinity setting in one single code point.

When specified, the referenced script will execute once for each discovered irq, with the sysfs device path and irq number passed as arguments. Note that the device path argument will point to the parent directory from which the irq attributes directory may be directly opened. The script may specify zero or more key=value pairs that will guide irqbalance in the management of that irq. Key=value pairs are printed by the script on stdout and will be captured and interpreted by irqbalance. Irqbalance expects a zero exit code from the provided utility. Recognized key=value pairs are:
Directs irqbalance to exclude the passed in irq from balancing
This allows a user to override the balance level of a given irq. By default the balance level is determined automatically based on the pci device class of the device that owns the irq.
This allows a user to override the numa node that sysfs indicates a given device irq is local to. Often, systems will not specify this information in ACPI, and as a result devicesa are considered equidistant from all numa nodes in a system. This option allows for that hardware provided information to be overridden, so that irqbalance can bias irq affinity for these devices toward its most local node. Note that specifying a -1 here forces irqbalance to consider an interrupt from a device to be equidistant from all nodes.
Have irqbalance write its process id to the specified file. By default no pidfile is written. The written pidfile is automatically unlinked when irqbalance exits. It is ignored when used with --debug or --foreground.

ENVIRONMENT VARIABLES

Same as --oneshot

Same as --debug

Provides a mask of cpus which irqbalance should ignore and never assign interrupts to

SIGNALS

Forces a rescan of the available irqs and system topology

Homepage

https://github.com/Irqbalance/irqbalance

Dec 2006 Linux