Re: [RFC 2/2] x86_64, mm: Reinsert the absent memory

From: Ingo Molnar
Date: Wed Jun 26 2013 - 11:58:44 EST



* Nathan Zimmer <nzimmer@xxxxxxx> wrote:

> On 06/26/2013 10:12 AM, Dave Hansen wrote:
> >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. :)
> More fun then one person can handle.
> I'll have to take this patch for a spin.

Please try latest -tip:master, there's a series of patches from Dave that
address this problem category.

Does it only happen with -g, or with regular perf record and/or with perf
top as well?

Thanks,

Ingo
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