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

       -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 powersave mode If more than <threshold> cpus are more than 1 standard devi-
	      ation 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

       -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.  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 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.

       -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.

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  IRQBAL-
	      ANCE_BANNED_CPUS=fc0'  would  prevent  irqbalance  from  assigning  irqs	to  the  7th-12th  cpus  (cpu6-cpu11)  or  'export IRQBAL-
	      ANCE_BANNED_CPUS=ff000000,00000001' would prevent irqbalance from assigning irqs to the 1st (cpu0) and 57th-64th cpus (cpu56-cpu63).

SIGNALS

       SIGHUP Forces a rescan of the available irqs and system topology

Homepage
       http://code.google.com/p/irqbalance

Linux								     Dec 2006							     IRQBALANCE(1)