smp_affinity and mask understanding

[Dan Track]

Hi,

I've been given a mask of "4040" to set as the smp_affinity for the
eth0 (irq 83),eth1 (irq 91), eth6 (irq 99) and eth8 (irq 131) cards in
my box. I'm struggling to understand how the mask "4040" relates to
cpu i.e. the range of cpus I have is CPU0-CPU15 in /proc/interrupts.
Can someone please describe the process to map this value to a
processor?

Currently I have 16 processors i.e. 4 cores on each cpu.

Thanks for your help.

Dan