linux-kernel - Re: Confusing behaviour with /proc/sys/kernel/nmi

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Message-ID: <20141105145356.GL135937@redhat.com>
Date:	Wed, 5 Nov 2014 09:53:56 -0500
From:	Don Zickus <dzickus@...hat.com>
To:	Anton Blanchard <anton@...ba.org>
Cc:	uobergfe@...hat.com, drjones@...hat.com, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog

On Wed, Nov 05, 2014 at 09:34:20AM +1100, Anton Blanchard wrote:
> 
> Hi,
> 
> commit 9919e39a1738 ("kvm: ensure hard lockup detection is disabled by
> default") provided a way for the kernel to disable the hard lockup
> detector at runtime.
> 
> I'm using it on ppc64 but notice some weird behaviour with the
> nmi_watchdog procfs variable. At boot, that the hard lockup
> detector appears to be enabled even when we disable it via
> watchdog_enable_hardlockup_detector(false):
> 
> # cat /proc/sys/kernel/nmi_watchdog 
> 1
> 
> I have to echo 0 to it then echo 1 again to enable it.

Hi Anton,

I believe Andrew answered the question for you, it's a WIP and we have
patches to clean that up.

I don't see ppc64 watchdog support in arch/powerpc, is that something you
are working with on implementing?

Cheers,
Don
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