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

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Date:	Thu, 12 Aug 2010 15:24:19 +0200
From:	Robert Richter <robert.richter@....com>
To:	Cyrill Gorcunov <gorcunov@...il.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 10.08.10 15:24:28, Cyrill Gorcunov wrote:
> On Tue, Aug 10, 2010 at 09:05:41PM +0200, Robert Richter wrote:
> > On 10.08.10 13:24:51, Cyrill Gorcunov wrote:
> > 
> > > It gets masked on NMI arrival, at least for some models (Core Duo, P4,
> > > P6 M and I suspect more theh that, that was the reason oprofile has
> > > it, also there is a note in SDM V3a page 643).
> > 
> > Yes, that's right, I never noticed that. Maybe it is better to
> > implement the apic write it in model specific code then.
> > 
> 
> Perhaps we can make it simplier I think, ie like it was before -- we just
> move it under your new DIE_NMIUNKNOWN, in separate patch of course. Though
> I'm fine with either way.

I do not understand why you want to put this in the 'unknown'
path. Isn't it necessary to unmask the vector with every call of the
nmi handler?

-Robert

> 
> (actually it's interesting to know wouldn't we leave lvt masked when
>  we hit 'second delayed nmi has arrived' situation, I guess we didn't
>  hit it before in real yet :-)
> 
> > -Robert
> > 
> > -- 
> > Advanced Micro Devices, Inc.
> > Operating System Research Center
> > 
> 	-- Cyrill
> --
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-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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