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 multi‐
       processor system in order to increase performance.


OPTIONS
       --oneshot
              Causes irqbalance to be run once, after which the daemon exits


       --debug
              Causes irqbalance to print extra debug information.  Implies --foreground


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


       --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


       --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  pre‐
              vent that cpu from waking up without need.


       --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



       --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  cap‐
              tured  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.

       --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


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


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





Linux                                        Dec 2006                               IRQBALANCE(1)