The irqbalance(1) man page does not contain documentation for the IRQBALANCE_BANNED_CPUS and IRQBALANCE_BANNED_INTERRUPTS environment variables. The following documentation will be added to this man page in a future release:
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 irqbalance from assigning irqs to the 1st (cpu0) and 57th-64th cpus (cpu56-cpu63).
Space separated list of integer irq's which irqbalance should ignore and never change the affinity of. i.e.
export IRQBALANCE_BANNED_INTERRUPTS="205 217 225"