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Date: Thu, 23 Apr 2015 22:01:04 +0200 (CEST)
From: Thomas Gleixner <tglx@linutronix.de>
To: Alexander Shishkin <alexander.shishkin@linux.intel.com>
cc: Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
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        Anton Blanchard <anton@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>, linux-kernel@vger.kernel.org,
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Subject: Re: [PATCH v1] watchdog: Use a reference cycle counter to avoid
 scaling issues
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On Thu, 23 Apr 2015, Alexander Shishkin wrote:

> The problem with using cycle counter for NMI watchdog is that its
> frequency changes with the corresponding core's frequency. This means
> that, in particular, if the core frequency scales up, watchdog NMI will
> arrive more frequently than what user requested through watchdog_thresh
> and also increasing the probability of setting off the hardlockup detector,
> because the corresponding hrtimer will keep firing at the same intervals
> regardless of the core frequency. And, if the core can turbo to up to 2.5x
> its base frequency (and therefore TSC) [1], we'll have the hrtimer and NMI

So you are saying that this M-5Y10 has a non-constant TSC again? You
really can't be serious about that.

Please provide the output of /proc/cpuinfo

Thanks,

	tglx