linux-kernel - Re: [PATCH] perf, x86: try to handle unknown nmis with running perfctrs

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Date:	Tue, 10 Aug 2010 20:16:27 +0400
From:	Cyrill Gorcunov <gorcunov@...il.com>
To:	Robert Richter <robert.richter@....com>
Cc:	Don Zickus <dzickus@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Lin Ming <ming.m.lin@...el.com>, Ingo Molnar <mingo@...e.hu>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH] perf, x86: try to handle unknown nmis with running
	perfctrs

On Tue, Aug 10, 2010 at 09:42:00AM +0200, Robert Richter wrote:
> On 09.08.10 16:02:45, Cyrill Gorcunov wrote:
> 
> > > @@ -1222,14 +1245,12 @@ perf_event_nmi_handler(struct notifier_block *self,
> > >  	regs = args->regs;
> > >  
> > >  	apic_write(APIC_LVTPC, APIC_DM_NMI);
> > 
> > If only I'm not missing something this apic_write should go up to
> > "case DIE_NMIUNKNOWN" site, no?
> 
> This seems to be code from the non-nmi implementation and can be
> removed at all, which should be a separate patch. The vector is
> already set up.
> 
> -Robert
>

No, this is just a short way to unmask LVTPC (which is required for
cpus). Actually lookig into this snippet I found that in p4 pmu
I've made one redundant unmaksing operation. will update as only
this area settle down.

	-- Cyrill
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