Re: [PATCH] perf/x86: check ucode before disabling PEBS on SandyBridge

Borislav Petkov
2012-06-12T17:15:07Z

On Tue, Jun 12, 2012 at 07:09:19PM +0200, Stephane Eranian wrote:
> > Instead of registering a microcode notifier, why not checking the
> > availability of pebs dynamically with each syscall in
> > intel_pmu_hw_config()? It looks like intel_snb_verify_ucode() is not
> > that much expensive. We can perform the check only if the event could
> > be for pebs and if pebs is broken. The check could be repeated when
> > setting up a new event after ucode could potentially has been updated
> > (e.g. after bringing a cpu online or so).

Yes, this will obviate the need for touching the microcode driver at all.

> That's what I had in my original version.

... and you decided not to do it like that because... ?

Thanks.

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