linux-kernel - Re: [PATCH] watchdog: Reduce message verbosity

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Date:   Mon, 30 Jul 2018 12:43:34 -0700
From:   Sinan Kaya <okaya@...nel.org>
To:     Don Zickus <dzickus@...hat.com>
Cc:     linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Colin Ian King <colin.king@...onical.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] watchdog: Reduce message verbosity

Hi Don,

On 7/30/2018 12:28 PM, Don Zickus wrote:
>> [    0.152492] NMI watchdog: Perf event create on CPU 0 failed with -2
>> [    0.156002] NMI watchdog: Perf NMI watchdog permanently disabled
> Hi Sinan,
> 
> Any reason why?  Usually when the 'perf event' fails, that indicates a
> system problem.  And most folks don't boot with the 'debug' option.  This
> means these unusual failures are hidden and become difficult to debug later
> when it propagates.

Sorry, I should have been more clear. I'm only suppressing the first
error message.

[    0.152492] NMI watchdog: Perf event create on CPU 0 failed with -2

Second message is still visible during boot. User knows that NMI 
watchdog is disabled.

[    0.156002] NMI watchdog: Perf NMI watchdog permanently disabled

Code is trying to probe the platform capabilities and is failing
because of missing PMU in the system. If someone is interested in
finding out why watchdog was disabled, they can turn on the debug
message level.

> 
> Or are you running the watchdog in a different configuration such that this
> is a common nuisance that you are trying to suppress?

Yup, system doesn't support PMU.

> 
> Cheers,
> Don
> 

Sinan