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SubjectRe: -rt IA64 update
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On Tue, 2006-05-30 at 08:15 +0200, Ingo Molnar wrote:
> * Simon Derr <Simon.Derr@bull.net> wrote:
> > * This kernel, when booting, prints:
> >
> > BUG in check_monotonic_clock at kernel/time/timeofday.c:164
> >
> > But I think this happens because two get_monotonic_clock() are racing
> > on two cpus. There is a lock to prevent the race, but it is a seqlock.
> > That means that it is okay if the race happens since another try will
> > be attempted, but the message that has been printed on the console
> > can't be removed, and the user is unnecessarily scared.

Simon, I suspect here you actually have unsynced ITCs, as the
check_monotonic_clock values are all locked w/ spinlocks.

You should probably add a cmpxchg in clocksource_itc_read() where you
currently do the if (last_itc < now), or you'll race on setting
last_itc. Let me know if you still see the issue w/ that fix.


> that too comes from the GTOD patchset. John, should we pick up the
> latest from -mm?

It would be nice to do so sooner or later. There will probably be a few
regressions as the bits in -mm are more stripped down then the older
code in -rt, but I'd work to fill those holes as they appeared.

Thomas, did you have any thought about the hrt code I sent you?

thanks
-john


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