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I've been given this question:

Assume that on some computer the overhead of trapping to the kernel for clock ticks is about 2 microsecond, with the handler requiring another 9 microseconds. Clock ticks typically occur at a frequency of 500Hz. What percentage of the CPU's time is devoted to the clock?

I have very little idea as where to start. I assume that it takes 11 microseconds for each clock tick, combining the overhead of trapping to the kernel and the handler. Other than that I am not sure how to approach this problem. Is anyone able to point me in the right direction?

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  • I have an example stating that I have a 500 MHz crystal and the counter is pulsed every 2 nsecs. Assuming a 32-bit register, interrupts can occur at intervals 2 nsec to 8.6 seconds. Does this relate to the problem above at all?
    – user3068177
    Apr 22, 2015 at 0:26
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    The question seems to be saying that there are 500 ticks a second, and each one takes 11 microseconds to process. So how much of each second is taken up by all this as a percentage.
    – Paul
    Apr 22, 2015 at 0:35
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    Aren't you supposed to do your own homework‽
    – Karan
    Apr 22, 2015 at 2:34

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