vmstat -i weirdness

[Tofik Suleymanov]

Hello list,

looks like `vmstat -i` acts weird on my machine after being 12-15 hours 
uptime.Here is the iutput of `vmstat -i`:

 > vmstat -i
interrupt                          total       rate
irq1: atkbd0                        6813          0
irq9: acpi0                         5397          0
irq12: psm0                        73782          1
irq14: ata0                        74209          1
irq15: ata1                           47          0
irq18: uhci2                           1          0
irq19: uhci3 ehci0                     1          0
irq21: iwi0                        35139          0
cpu0: timer                    105315537       1999
Total                          105510926       2003
 >                                                   

Strange is that for example atkbd0 has rate of 0, but total interrupts 
count of atkbd0 is growing.
Machine runs FreeBSD 6.1 RELEASE p11 with  pretty common  kernel.

Is this known behaviour ?

many thanks,
Tofig Suleymanov.