irqbalance(1)
NAME
irqbalance - distribute hardware interrupts across processors on a multiprocessor system
SYNOPSIS
irqbalance
DESCRIPTION
The purpose of irqbalance is to distribute hardware interrupts across processors on a multiprocessor system in order to increase performance.
OPTIONS
-o, --oneshot
Causes irqbalance to be run once, after which the daemon exits.
-d, --debug
Causes irqbalance to print extra debug information. Implies
--foreground.
-f, --foreground
Causes irqbalance to run in the foreground (without --debug).
-j, --journal
Enables log output optimized for systemd-journal.
-h, --hintpolicy=[exact | subset | ignore]
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
affinity hint.
ignore IRQ affinity hint value is completely ignored.
The default value for hintpolicy is ignore.
-p, --powerthresh=<threshold>
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.
-i, --banirq=<irqnum>
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
--deepestcache=<integer>
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
level), will cause irqbalance to see balancing as unnecessary.
irqbalance --deepestcache=2
The default value for deepestcache is 2.
-l, --policyscript=<script>
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:
ban=[true | false]
Directs irqbalance to exclude the passed in IRQ from balancing.
balance_level=[none | package | cache | core]
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.
numa_node=<integer>
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 devices
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.
hintpolicy=[exact | subset | ignore ]
This allows a user to override the globally set hintpolicy for a
given irq. Use is identical to the --hintpolicy setting, but
applied per irq
-s, --pid=<file>
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.
-t, --interval=<time>
Set the measurement time for irqbalance. irqbalance will sleep
for <time> seconds between samples of the irq load on the system
cpus. Defaults to 10.
ENVIRONMENT VARIABLES
IRQBALANCE_ONESHOT
Same as --oneshot.
IRQBALANCE_DEBUG
Same as --debug.
IRQBALANCE_BANNED_CPUS
Provides a mask of CPUs which irqbalance should ignore and never
assign interrupts to.
SIGNALS
SIGHUP Forces a rescan of the available IRQs and system topology.
Homepage
https://github.com/Irqbalance/irqbalance
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