Re: 2.6.14-rt13

From: Fernando Lopez-Lezcano
Date: Fri Nov 18 2005 - 17:06:14 EST

On Fri, 2005-11-18 at 16:54 -0500, Lee Revell wrote:
> On Fri, 2005-11-18 at 10:02 -0800, Fernando Lopez-Lezcano wrote:
> > You mentioned before that the TSC's from both cpus could drift from
> > each other over time. Assuming that is the source of timing (I have no
> > idea) that could explain the behavior of Jack, it gets a reference
> > time from one of the cpus and then compares that with what it gets
> > from either cpu depending on where it is running at a given time. If
> > it is the same cpu all is fine, if it is the other and it has drifted
> > then the warning is printed.
> Yes, JACK uses rdtsc() for microsecond resolution timing and assumes
> that the TSCs are in sync.
> I've asked on this list what a better time source could be and didn't
> get any useful responses, people just told me "use gettimeofday()" which
> is WAY too slow.

Arghhh, at least I take this as a confirmation that the TSCs do drift
and there is no workaround. It currently makes the -rt/Jack combination
not very useful, at least in my tests.

Is there a way to resync the TSCs?
-- Fernando

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