Message-ID: <51CB04C7.8060702@intel.com>
Date: Wed, 26 Jun 2013 08:12:07 -0700
From: Dave Hansen <dave.hansen@intel.com>
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To: Nathan Zimmer <nzimmer@sgi.com>
CC: Ingo Molnar <mingo@kernel.org>, holt@sgi.com, travis@sgi.com,
        rob@landley.net, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
        yinghai@kernel.org, akpm@linux-foundation.org,
        gregkh@linuxfoundation.org, x86@kernel.org, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: Re: [RFC 2/2] x86_64, mm: Reinsert the absent memory
References: <1371831934-156971-1-git-send-email-nzimmer@sgi.com> <1371831934-156971-3-git-send-email-nzimmer@sgi.com> <20130623092840.GB13445@gmail.com> <20130624203657.GA107621@asylum.americas.sgi.com> <20130626121430.GA4980@gmail.com> <20130626144903.GA2210@asylum.americas.sgi.com>
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On 06/26/2013 07:49 AM, Nathan Zimmer wrote:
> My guess it is the NMIs overwhelming the system but I have not found a good way
> to profile perf gone wild so it is only a guess.

I've got an 80-core system and the symptoms sound similar to perf issues
I'm seeing.  Dropping the sample rate helped for me, and there's a patch
in -tip at the moment to do it automatically:

> http://git.kernel.org/cgit/linux/kernel/git/tip/tip.git/commit/?id=14c63f17b1fde5a575a28e96547a22b451c71fb5

Looks like you've also found that debugging NMIs is fun. :)
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