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

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Message-ID: <20180730192800.nqdhugzbxmin6e25@redhat.com>
Date:   Mon, 30 Jul 2018 15:28:01 -0400
From:   Don Zickus <dzickus@...hat.com>
To:     Sinan Kaya <okaya@...nel.org>
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

On Mon, Jul 30, 2018 at 12:09:47PM -0700, Sinan Kaya wrote:
> Reducing the verbosity level to debug for people that are interested in
> debugging watchdog issues.
> 
> [    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.

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

Cheers,
Don

> 
> Signed-off-by: Sinan Kaya <okaya@...nel.org>
> ---
>  kernel/watchdog_hld.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/watchdog_hld.c b/kernel/watchdog_hld.c
> index e449a23e9d59..1f7020d65d0a 100644
> --- a/kernel/watchdog_hld.c
> +++ b/kernel/watchdog_hld.c
> @@ -175,8 +175,8 @@ static int hardlockup_detector_event_create(void)
>  	evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
>  					       watchdog_overflow_callback, NULL);
>  	if (IS_ERR(evt)) {
> -		pr_info("Perf event create on CPU %d failed with %ld\n", cpu,
> -			PTR_ERR(evt));
> +		pr_debug("Perf event create on CPU %d failed with %ld\n", cpu,
> +			 PTR_ERR(evt));
>  		return PTR_ERR(evt);
>  	}
>  	this_cpu_write(watchdog_ev, evt);
> -- 
> 2.17.1
>