Re: Measured overhead of timer interrupts

Robert G. Brown (
Thu, 5 Aug 1999 11:30:45 -0400 (EDT)

On Tue, 20 Jul 1999, Pavel Machek wrote:

> Hi!
> > > On Mon, Jul 19 1999, Artur Skawina wrote:
> > > > what i would be interested in seeing is: the time it takes to
> > > > run a cpu bound app (eg raytracing am image) with HZ=100 and HZ=1024.
> > > > That would give a more realistic approximation of the overhead that
> > > > increasing HZ adds.
> > >
> > > Then do the bench, nobody prevents you from doing so.
> >
> > Should HZ=1024 be safe on x86?
> Yes. Irda used to be broken w.r.t. HZ but is fixed now. Oh and you'll
> need to recompile things like top. But with exception of pstools
> HZ=1024 i386 system works just well.

Sorry for the late hit (I've been on vacation) but, would it be
worthwhile to add HZ to a file in /proc, e.g. /proc/sys/kernel/hz? One
could then patch and recompile pstools (and possibly things like games
that might care) to read the value. Indeed, one could even permit the
value to be set via the proc point and let people retune from coarse to
ultra-fine as CPU speeds and the like continue to increase.

Just an opinion, but a solution that is properly integrated and is
scalable in the future seems preferable to just altering the #define.


Robert G. Brown
Duke University Dept. of Physics, Box 90305
Durham, N.C. 27708-0305
Phone: 1-919-660-2567 Fax: 919-660-2525

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