-Frequency (Hz): the number of interruptions per second (Hz)
-
-Total Duration (nsec): the sum of each interrupt duration in nsec
+Each field of the interrupt viewer is summarized as follows:
+
+- CPUID: processor ID
+
+- IrqId: IRQ ID
+
+- Frequency (Hz): the number of interrupts per second (Hz).
+ We compute the total number of interrupts. Then
+ we divide it by the time interval.
+
+- Total Duration (nsec): the sum of each interrupt duration in nsec.
+ For a given Irq ID, we sum the duration of each interrupt
+ to give us the total duration
+
+- Duration Standard_deviation = sqrt(1/N Sum ((xi -Xa)^2)) where
+ N: number of interrupts
+ xi: duration of an interrupt (nsec)
+ Xa: average duration (nsec)
+ The formula is taken from wikipedia: http://en.wikipedia.org/wiki/Standard_deviation.
+ To calculate the duration standard deviation, we make two EventsRequest passes to the main window.
+ In the first EventsRequest pass, we calculate the total number of interrupts to compute for
+ the average Xa. In the second EventsRequest pass, calculate the standard deviation.
+