Re: non-invariant tsc and cputicker

On Monday 06 December 2010 02:09 pm, Andriy Gapon wrote:
> on 06/12/2010 21:01 Jung-uk Kim said the following:
> > :-) Don't get me wrong, I generally agree with you *iff* it does
> > : not
> >
> > hurt too much.  Anyway, this issue should be resolved from the
> > root, i.e., kern_resouce.c, if possible.
>
> But what to resolve there?

Better algorithm for stat.

> I just want to always have a stable source "cpu ticks", and then
> everything else should just work?

If we had one, yes.  But we don't, at least for old x86 hardware. :-(

> BTW, if someone comes up with a patch for more or less correct
> accounting when "cpu ticks" frequency is allowed to change, then I
> am all for it. But, IMO, it's just easier to use stable "cpu
> ticks".

If it doesn't hurt too much, yes.  Remember the P-state invariant CPUs 
are pretty new.  SMP-correct TSC is quite rare if there is any.

Jung-uk Kim