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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