High interrupt CPU usage in top

[Matthew Dillon]

:I did 16k aswell, and yes it was much lower on both OS's. I figured you 
:wanted a 'worst-case' sorta thing is all :P Oh, and the whole mess with 
:the hard disk set up was very temporary, I was just too lazy to mess 
:about changing jumpers around really.
:
:Is the interrupt issue some sort of accounting stuff in the kernel like 
:Joerg said? If so, is that debugging info of sorts which may possibly be 
:removed / optional in future releases?

    Well, its hard to say.  After examining the code I found that there
    *ARE* cases where the statistics clock is counting non-interrupts as
    interrupts, but I don't know how large an effect that has on the
    accounting.

    Another measure of interrupt overhead is to simply do a 'ps axl' and
    observe the run times for the various interrupt threads.  Perhaps
    do a before-and-after comparison using buildworld as a time and 
    figure the time verses the total time it took to build the world.

					-Matt
					Matthew Dillon 
					<dillon at xxxxxxxxxxxxx>