Re: test time-warps [was: Re: 2.6.14-rt13]

[Ingo Molnar]

* Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> > > Apparently that's the case.
> >
> > What about periodically re-syncing the TSCs on the cpus?  Are they
> > writeable?
> 
> I believe you can reset them to zero, but I don't think you can set 
> them to anything else.  I had to do something similar a few years ago, 
> and I don't have the specs in front of me, so this is coming straight 
> from memory.

on a reasonably new CPU you ought to be able to set the 64-bit value - 
but that doesnt change the fundamental fact: we have no idea how much 
time has passed while we were in HLT. Especially with things like 
dyntick/noidle we could spend _alot_ of time in HLT, and the TSC could 
drift significantly. How do we know how much that is?

	Ingo
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