Re: clocksource

Roman Zippel
2006-06-15T11:44:21Z

Hi,

On Thu, 8 Jun 2006, john stultz wrote:

> > This code gets only limited testing in -mm, it needs to run for weeks
> > or months, which I don't expect from the average -mm kernel. This makes
> > userspace simulations so damn important and if you don't do this, you're
> > playing a very risky game with a kernel which is supposed to be stable.
>
> Agreed, simulation is nice. Thus, I've revived the old simulator which
> builds using the existing code in -mm. Its a bit fast/dirty and isn't
> exactly like your sim, but maybe you can take a look at it and send
> patches to improve it?
>
> You can find it at:
> http://sr71.net/~jstultz/tod/simulator_C2.tar.bz2

At http://www.xs4all.nl/~zippel/ntp/simulator_C2+patches.tar.bz2 is my
version where I added a number of patches (all p? patches) to get it into
an acceptable state. You have a number of bugs which actually didn't let
the clock oscillate that much but instead added random jitter (and in some
cases a lot of it).

I disabled the lost interrupt simulation, so the effect of adjustments are
better visible, the error should return to near zero after it. Look for
the "ppm" prints and watch the time difference.
In the series file you can enable some debug patches (d?) to add extra
prints or simulate large update delays to see the effect on the error
difference.

bye, Roman