CPUID: processor ID

IrqId: IRQ ID

Frequency (Hz): the number of interruptions per second (Hz)

Total Duration (nsec): the sum of each interrupt duration in nsec

Duration standard deviation (nsec):   taken from 
http://en.wikipedia.org/wiki/Standard_deviation
Duration Standard_deviation  = sqrt(1/N Sum ((xi -Xa)^2)) where
N: the total number of interrupts 
xi: the duration of an interrupt
Xa: the average duration is the total duration divided by the total number of interrupts (N)

Max IRQ handler duration (nsec) [time interval]:   the longest IRQ handler duration in nsec.  

Average period (nsec): 1/Frequency
 
Period Standard_deviation  = sqrt(1/N Sum ((xi -Xa)^2)) where
N:  number of interrupts 
xi: duration of an interrupt
Xa: Average period in nsec