Re: TSC clock going backwards on suspend/resume

[Matthias Drochner <M.Drochner%fz-juelich.de@localhost>]

ad%NetBSD.org@localhost said:
> > It is not explained what the "drift" and "skew" are about,
> It's implied by the words used. It could use a comment block. Skew is
> an observed offset between CPUs

OK, I believe I understand the code now... It could be noted that
it is the difference for each AP relative to the BP, sampled
during the *sync* process.

> Drift is the process of the offset changing over time.

The "over time" is a bit dubious here afais -- it is taken
only once, over a random interval and not weighted. So I think
it is only suitable to detect spontaneous misbehaviour, not to
measure a real clock frequency difference.
Does this happen in practice?

> > *sync* functions are usually called twice
> It's to elide major cache effects. The result from the first pass is
> discarded.

Would you mind if I put the reprtition into the functions
instead of the callers, and also add calls to the acpi
wakeup?

best regards
Matthias




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