Re: [PATCH -tip/core/rcu 1/6] Cleanups and fixes for RCU in faceof heavy CPU-hotplug stress

[Ingo Molnar]

* Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx> wrote:

> I would not trust this architecture for synchronization tests. 
> There has been reports of a hardware bug affecting the cmpxchg 
> instruction in the field. The load fence normally implied by the 
> semantic seems to be missing. AFAIK, AMD never acknowledged the 
> problem.

If cmpxchg was broken i'd be having far worse problems and very 
widely so.

FYI, this was the same box i prototyped/developed -rt on, which uses 
cmpxchg for _everything_.

That's not a proof of course (it's near impossible to prove the lack 
of a bug), but it's sure a strong indicator and you'll need to 
provide far more proof of misbehavior before i discount a bona fide 
regression on this box.

	Ingo
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