Date: Tue, 12 Jun 2012 19:15:24 +0200
From: Borislav Petkov <bp@amd64.org>
To: Stephane Eranian <eranian@google.com>
Cc: Robert Richter <robert.richter@amd.com>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        linux-kernel@vger.kernel.org, andi@firstfloor.org, mingo@elte.hu,
        ming.m.lin@intel.com, Andreas Herrmann <andreas.herrmann3@amd.com>,
        Dimitri Sivanich <sivanich@sgi.com>,
        Dmitry Adamushko <dmitry.adamushko@gmail.com>
Subject: Re: [PATCH] perf/x86: check ucode before disabling PEBS on
 SandyBridge
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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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Boris.

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