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SubjectRe: using the pentium cycle counter on MP's
Date
> is the cycle counter on any one processor guaranteed to be within a
> certain distance of the value on all the other processors, or does a
> restart leave them pretty much randomly staggered by a few
> microseconds or more ?

They appear to be locked on current intel hardware. There isnt a written
guarantee of that anywhere I can find.

> does linux do anything to prevent the use of the cycle counters from
> being used as extremely accurate real time clocks (i'm thinking of the
> idle stuff - does this in anyway stop the cycle counter from
> advancing ?)

Not on intel chips. There are some 'funnies' with idle time and other
processors which do even more serious power optimisation on idle. Finally
APM may change the clock or stop it


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