Re: Incorrect CPU process accounting using CONFIG_HZ=100

[Pavel Machek]

On Thu 2006-06-22 20:36:39, Al Boldi wrote:
> Jan Engelhardt wrote:
> > >Setting CONFIG_HZ=100 results in incorrect CPU process accounting.
> > >
> > >This can be seen running top d.1, that shows top, itself, consuming 0ms
> > >CPUtime.
> > >
> > >Will this bug have consequences for sched.c?
> >
> > Works for me, somewhat.
> > TIME+ says 0:00.02 after 70 secs. (Ergo: top is not expensive on this
> > CPU.)
> 
> That's what I thought for a long time.  But at closer inspection, top d.1 
> slows down other apps by about the same amount of time at 1000Hz and 100Hz, 
> only at 1000Hz it is accounted for whereas at 100Hz it is not.

It is not a bug... it is design decision. If you eat "too little" cpu
time, you'll be accouted 0 msec. That's what happens at 100Hz...
										Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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