Re: [PATCH 5/5] perf, x86: Move NMI clearing to end of PMI handlerafter the counter registers are reset

From: Ingo Molnar
Date: Wed Feb 13 2013 - 04:10:35 EST

* Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:

> On Tue, Feb 12, 2013 at 09:43:46AM +0100, Ingo Molnar wrote:
> > Was this stress-tested on all affected main CPU types, or only
> > on Haswell?
> I tested it on Haswell and Ivy Bridge. I can also try Westmere
> and a Saltwell(Atom), but for the majority of other family 6
> systems I'll need to rely on the community.

The systems you tested should be OK.

> White listing is somewhat difficult because it affects the
> architectural mode too.

Yeah, I'd rather avoid that.

> I don't really expect problems from this change, we should
> probably have always done it like this.

I expect potential problems: the ordering of the operations in
the NMI handler was always very fragile, resulting in hard to
debug hangs - which sometimes needed hours long very intense PMU
stress-testing to trigger.

That is why I asked how heavily you've tested this. Once the
series passes review I'll keep this patch last to make it easy
to revert/zap if it causes problems.


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at