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


       --debug
              Causes irqbalance to run in the foreground and extra debug information to be printed


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


NOTES
       The purpose of irqbalance is to distribute interrupts accross cpus in an smp system such that  cache-domain  affinity  is
       maximized for each irq.  In other words, irqbalance tries to assign irqs to cpu cores such that each irq stands a greater
       chance of having its interrupt handler be in cache when the irq is asserted to the cpu.  This raises  a  few  interesting
       cases in which the behavior of irqbalance may be non-intuitive.  Most notably, cases in which a system has only one cache
       domain.  Nominally these systems are only single cpu environments, but can also be found in  multi-core  environments  in
       which  the  cores  share  an L2 cache.  In these situations irqbalance will exit immediately, since there is no work that
       irqbalance can do which will improve interrupt handling performance.  This is normal and not cause for concern.  For more
       information regarding irqbalance, please visit http://irqbalance.org/



Linux                                                       Dec 2006                                               IRQBALANCE(1)