Re: Why HZ on i386 is 100 ?

Pavel Machek
2002-04-22T16:09:43Z

Hi!

> Davide> i still have pieces of paper on my desk about tests done on
> Davide> my dual piii where by hacking HZ to 1000 the kernel build
> Davide> time went from an average of 2min:30sec to an average
> Davide> 2min:43sec. that is pretty close to 10%
>
> The last time I measured timer tick overhead on ia64 it was well below
> 1% of overhead. I don't really like using kernel builds as a
> benchmark, because there are far too many variables for the results to
> have any long-term or cross-platform value. But since it's popular, I
> did measure it quickly on a relatively slow (old) Itanium box: with
> 100Hz, the kernel compile was about 0.6% faster than with 1024Hz
> (2.4.18 UP kernel).

.5% still looks like a lot to me. Good compiler optimization is .5% on
average...

And think what it does with old 386sx.. Maybe time for those "tick on demand"
patches?
Pavel
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