[PATCH] watchdog: Reduce message verbosity

[PATCH] watchdog: Reduce message verbosity

[Sinan Kaya]

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

Signed-off-by: Sinan Kaya <okaya@kernel.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

Re: [PATCH] watchdog: Reduce message verbosity

[Don Zickus]

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@kernel.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
> 

Re: [PATCH] watchdog: Reduce message verbosity

[Sinan Kaya]

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

Re: [PATCH] watchdog: Reduce message verbosity

[Don Zickus]

On Mon, Jul 30, 2018 at 12:43:34PM -0700, Sinan Kaya wrote:
> 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.

Hi Sinan,

Oh, I see.  You are just trying to hide the always failing probe.  It seems
to make sense.

Acked-by: Don Zickus <dzickus@redhat.com>

Re: [PATCH] watchdog: Reduce message verbosity

[Thomas Gleixner]

On Mon, 30 Jul 2018, 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

This changelog is utterly useless. 

Thanks,

	tglx

Re: [PATCH] watchdog: Reduce message verbosity

[Sinan Kaya]

On 8/2/2018 5:18 AM, Thomas Gleixner wrote:
> On Mon, 30 Jul 2018, 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
> 
> This changelog is utterly useless.

I'll capture my conversation with Don into the commit message and post
post V2.

> 
> Thanks,
> 
> 	tglx
>