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IRQBALANCE(1)                     irqbalance                     IRQBALANCE(1)

NAME
       irqbalance - distribute hardware interrupts across processors on a mul-
       tiprocessor system
SYNOPSIS
       irqbalance

DESCRIPTION
       The purpose of irqbalance is distribute hardware interrupts across pro-
       cessors 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)

       -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
       affintiy 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  power-
              save 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 irqbal-
              ance partitions cache  domains.  Without  specified,  irqbalance
              searches  the  available  deepest  cache.  This  can  affect how
              irqbalance builds up the CPU tree.  For  example,  on  a  system
              where  all  the CPU cores being within the same L3 cache domain,
              one can let irqbalance build up the CPU  tree  on  L2  cache  by
              using the following command line: irqbalance --deepestcache=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  indi-
              cates  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 over-
              ridden,  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.
       -s, --pid=<file>
              Have irqbalance write its process id to the specified file.   By
              default no pidfile is written.  The written pidfile is automati-
              cally unlinked when irqbalance exits. It is  ignored  when  used
              with --debug or --foreground.

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.  This is a hex mask  without  the  leading
              '0x',  on systems with large numbers of processors each group of
              eight hex digits is separated  by  a  comma  ','.  i.e.  `export
              IRQBALANCE_BANNED_CPUS=fc0`   would   prevent   irqbalance  from
              assigning irqs to the  7th-12th  cpus  (cpu6-cpu11)  or  `export
              IRQBALANCE_BANNED_CPUS=ff000000,00000001`  would prevent irqbal-
              ance from assigning irqs to the 1st (cpu0)  and  57th-64th  cpus
              (cpu56-cpu63).   If  not  specified, irqbalance use mask of iso-
              lated and adaptive-ticks CPUs  on  the  system  as  the  default
              value.

SIGNALS
       SIGHUP Forces a rescan of the available irqs and system topology

Homepage
       https://github.com/Irqbalance/irqbalance


Linux                              Dec 2006                      IRQBALANCE(1)