Re: [Xen-devel] HVM SMP linux guest hangs in cpu_idle() with EFLAGS.IF = 1

[Gianni Tedesco <gianni.tedesco@xxxxxxxxxx>]

On Tue, 2010-07-13 at 17:31 +0100, Gianni Tedesco wrote:
> > > I used the same setup to test RHEL5, RHEL5.[1234] and can only reproduce
> > > on 5.1 and 5.2.
> > 
> > Ok, did you look in the changelog for RHEL5.3 and above. It might be
> > that you are hitting a bug that was fixed.
> 
> There are several potential candidates but difficult to get further info
> due to redhat bugzilla. Trying to get in touch with a relevant engineer
> to confirm / falsify that theory.

The patch "Fix gettimeofday reliability issues with TSC, HPET, and
PM-Timer" seems to mask the bug and make it much less reproducable. This
patch was to fix some gettimeofday-goes-backwards issues on bare metal.
As a result of this I can now confirm the bug is still present in
RHEL5.3 at least - I shall test the others shortly.

Looks like TSC/PIT timesource is either a) unreliable in xen, b)
unreliable in RHEL kernels or c) all of the above.

Gianni


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