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Message-ID: <4DA756AC.6030201@gmail.com>
Date: Fri, 15 Apr 2011 00:18:52 +0400
From: Cyrill Gorcunov <gorcunov@gmail.com>
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To: Don Zickus <dzickus@redhat.com>
CC: Ingo Molnar <mingo@elte.hu>, Lin Ming <ming.m.lin@intel.com>,
        Shaun Ruffell <sruffell@digium.com>,
        Maciej Rutecki <maciej.rutecki@gmail.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Stephane Eranian <eranian@google.com>,
        Robert Richter <robert.richter@amd.com>,
        lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -tip] perf, x86: fix unknown NMIs on a Pentium4 box
References: <4DA70950.3060102@openvz.org> <20110414174327.GA8863@elte.hu> <20110414183231.GN16939@redhat.com> <20110414184606.GD16064@elte.hu> <4DA74E5D.4060002@openvz.org> <20110414195748.GO16939@redhat.com> <4DA75373.9040705@openvz.org>
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On 04/15/2011 12:05 AM, Cyrill Gorcunov wrote:
...
>>
>> I don't think this patch will work.  It would make sense if the unmasking
>> happened _after_ the "if (!handled)" path, but that is not the path Ingo
>> wanted for v1.
> 
> This thing happened if inflight nmi reaches the system and note that inflight
> NMI comes from perf and masks lvt entry, it has nothing to do with "handled" but
> rather the _fact_ that NMI reached apic via LVTPC and as result -- masked it.
> Don, I might be missin something, brain is slowly going to sleep :)
> 

Seems I'm wrong in this assumption, otherwise when this mechanism was
introduced for first time every in-flight nmi catched would block further
perf activity.

>>
>> Cheers,
>> Don
>>

-- 
    Cyrill