Re: [RFC patch 0/4] TSC calibration improvements

[Ingo Molnar <mingo@elte.hu>]

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Thu, 4 Sep 2008, Linus Torvalds wrote:
> > 
> > Face it, if somebody tries to make QUICK_PIT_MS be so large as to 
> > that be an issue, then the whole point of the function goes away.
> 
> Btw, the same is true of adding any random "sanity checking". The 
> point of that thing was to simply only work when the PIT works as 
> advertized, and fail immediately if it doesn't. Even *if* you were to 
> pick a big calibration delay *and* if you happened to have a PIT that 
> is broken and doesn't wrap correctly, the design of the thing would 
> mean that it would then fail the calibration already.
> 
> Exactly because it would _see_ that it's not wrapping.

yeah - pit_expect_msb() would return after 50,000 iterations with a 
failure. So i was wondering whether for such PITs we _want_ the slow and 
complicated case to run.

Probably not, because the PIT could quite likely still be counting very 
precisely as long as no wraparound was involved.

	Ingo