+ nmi-watchdog-quiet-down-the-boot-messages.patch added to -mm tree

+ nmi-watchdog-quiet-down-the-boot-messages.patch added to -mm tree

[akpm]

The patch titled
     Subject: nmi watchdog: quiet down the boot messages
has been added to the -mm tree.  Its filename is
     nmi-watchdog-quiet-down-the-boot-messages.patch

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------------------------------------------------------
From: Don Zickus <dzickus@redhat.com>
Subject: nmi watchdog: quiet down the boot messages

A bunch of bugzillas have complained how noisy the nmi_watchdog is during
boot-up especially with its expected failure cases (like virt and bios
resource contention).

This is my attempt to quiet them down and keep it less confusing for the
end user.  What I did is print the message for cpu0 and save it for future
comparisons.  If future cpus have an identical message as cpu0, then don't
print the redundant info.  However, if a future cpu has a different
message, happily print that loudly.

Before the change, you would see something like:

    ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
    CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
    Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
    ... version:                2
    ... bit width:              40
    ... generic registers:      2
    ... value mask:             000000ffffffffff
    ... max period:             000000007fffffff
    ... fixed-purpose events:   3
    ... event mask:             0000000700000003
    NMI watchdog enabled, takes one hw-pmu counter.
    Booting Node   0, Processors  #1
    NMI watchdog enabled, takes one hw-pmu counter.
     #2
    NMI watchdog enabled, takes one hw-pmu counter.
     #3 Ok.
    NMI watchdog enabled, takes one hw-pmu counter.
    Brought up 4 CPUs
    Total of 4 processors activated (22607.24 BogoMIPS).

After the change, it is simplified to:

    ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
    CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
    Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
    ... version:                2
    ... bit width:              40
    ... generic registers:      2
    ... value mask:             000000ffffffffff
    ... max period:             000000007fffffff
    ... fixed-purpose events:   3
    ... event mask:             0000000700000003
    NMI watchdog enabled, takes one hw-pmu counter.
    Booting Node   0, Processors  #1 #2 #3 Ok.
    Brought up 4 CPUs

Signed-off-by: Don Zickus <dzickus@redhat.com>
Reported-by: Nathan Zimmer <nzimmer@sgi.com>
Tested-by: Nathan Zimmer <nzimmer@sgi.com>
Cc: Joe Perches <joe@perches.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 kernel/watchdog.c |   19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff -puN kernel/watchdog.c~nmi-watchdog-quiet-down-the-boot-messages kernel/watchdog.c
--- a/kernel/watchdog.c~nmi-watchdog-quiet-down-the-boot-messages
+++ a/kernel/watchdog.c
@@ -377,6 +377,13 @@ static int watchdog_nmi_enable(int cpu)
 	struct perf_event_attr *wd_attr;
 	struct perf_event *event = per_cpu(watchdog_ev, cpu);
 
+	/*
+	 * People like the simple clean cpu node info on boot.
+	 * Reduce the watchdog noise by only printing messages
+	 * that are different from what cpu0 displayed.
+	 */
+	static unsigned long cpu0_err;
+
 	/* is it already setup and enabled? */
 	if (event && event->state > PERF_EVENT_STATE_OFF)
 		goto out;
@@ -390,11 +397,21 @@ static int watchdog_nmi_enable(int cpu)
 
 	/* Try to register using hardware perf events */
 	event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback, NULL);
+
+	/* save cpu0 error for future comparision */
+	if (cpu == 0 && IS_ERR(event))
+		cpu0_err = PTR_ERR(event);
+
 	if (!IS_ERR(event)) {
-		pr_info("enabled, takes one hw-pmu counter.\n");
+		/* only print for cpu0 or different than cpu0 */
+		if (cpu ==0 || cpu0_err)
+			pr_info("enabled, takes one hw-pmu counter.\n");
 		goto out_save;
 	}
 
+	/* skip displaying the same error again */
+	if (cpu > 0 && (PTR_ERR(event) == cpu0_err))
+		return PTR_ERR(event);
 
 	/* vary the KERN level based on the returned errno */
 	if (PTR_ERR(event) == -EOPNOTSUPP)
_
Subject: Subject: nmi watchdog: quiet down the boot messages

Patches currently in -mm which might be from dzickus@redhat.com are

origin.patch
linux-next.patch
nmi-watchdog-quiet-down-the-boot-messages.patch
nmi-watchdog-fix-for-lockup-detector-breakage-on-resume.patch
nmi-watchdog-fix-for-lockup-detector-breakage-on-resume-fix.patch
nmi-watchdog-fix-for-lockup-detector-breakage-on-resume-fix-fix-fix.patch
nmi-watchdog-fix-for-lockup-detector-breakage-on-resume-fix-fix.patch
nmi-watchdog-fix-for-lockup-detector-breakage-on-resume-v2.patch
nmi-watchdog-fix-for-lockup-detector-breakage-on-resume-v2-fix.patch

Re: + nmi-watchdog-quiet-down-the-boot-messages.patch added to -mm tree

[Ingo Molnar]

* akpm@linux-foundation.org <akpm@linux-foundation.org> wrote:

> From: Don Zickus <dzickus@redhat.com>
> Subject: nmi watchdog: quiet down the boot messages
> 
> A bunch of bugzillas have complained how noisy the nmi_watchdog is during
> boot-up especially with its expected failure cases (like virt and bios
> resource contention).
> 
> This is my attempt to quiet them down and keep it less confusing for the
> end user.  What I did is print the message for cpu0 and save it for future
> comparisons.  If future cpus have an identical message as cpu0, then don't
> print the redundant info.  However, if a future cpu has a different
> message, happily print that loudly.
> 
> Before the change, you would see something like:
> 
>     ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
>     CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
>     Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
>     ... version:                2
>     ... bit width:              40
>     ... generic registers:      2
>     ... value mask:             000000ffffffffff
>     ... max period:             000000007fffffff
>     ... fixed-purpose events:   3
>     ... event mask:             0000000700000003
>     NMI watchdog enabled, takes one hw-pmu counter.
>     Booting Node   0, Processors  #1
>     NMI watchdog enabled, takes one hw-pmu counter.
>      #2
>     NMI watchdog enabled, takes one hw-pmu counter.
>      #3 Ok.
>     NMI watchdog enabled, takes one hw-pmu counter.
>     Brought up 4 CPUs
>     Total of 4 processors activated (22607.24 BogoMIPS).

the problem really was that it didn't print which CPU it 
referred to - it just repeated the same message over and over 
again.

If it said:

     NMI watchdog enabled on CPU#0, takes one hw-pmu counter.

it would be far less confusing.

This:

> After the change, it is simplified to:
> 
>     ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
>     CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
>     Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
>     ... version:                2
>     ... bit width:              40
>     ... generic registers:      2
>     ... value mask:             000000ffffffffff
>     ... max period:             000000007fffffff
>     ... fixed-purpose events:   3
>     ... event mask:             0000000700000003
>     NMI watchdog enabled, takes one hw-pmu counter.
>     Booting Node   0, Processors  #1 #2 #3 Ok.
>     Brought up 4 CPUs

Is fine too but should be clarified to something like:

     NMI watchdog enabled on all CPUs, permanently consumes one hw-PMU counter

(Please note the capitalization of 'PMU' as well.)

Thanks,

	Ingo

Re: + nmi-watchdog-quiet-down-the-boot-messages.patch added to -mm tree

[Don Zickus]

On Mon, Jun 11, 2012 at 10:47:44AM +0200, Ingo Molnar wrote:
> >     NMI watchdog enabled, takes one hw-pmu counter.
> >     Booting Node   0, Processors  #1
> >     NMI watchdog enabled, takes one hw-pmu counter.
> >      #2
> >     NMI watchdog enabled, takes one hw-pmu counter.
> >      #3 Ok.
> >     NMI watchdog enabled, takes one hw-pmu counter.
> >     Brought up 4 CPUs
> >     Total of 4 processors activated (22607.24 BogoMIPS).
> 
> the problem really was that it didn't print which CPU it 
> referred to - it just repeated the same message over and over 
> again.
> 
> If it said:
> 
>      NMI watchdog enabled on CPU#0, takes one hw-pmu counter.
> 
> it would be far less confusing.

Sure.  The problem SGI has with 4096 cpus is the volume.  Specifying which
cpu the message belongs to, I do not think helps with this problem.

> 
> This:
> 
> > After the change, it is simplified to:
> > 
> >     ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
> >     CPU0: Intel(R) Core(TM)2 Quad CPU    Q9550  @ 2.83GHz stepping 0a
> >     Performance Events: PEBS fmt0+, Core2 events, Intel PMU driver.
> >     ... version:                2
> >     ... bit width:              40
> >     ... generic registers:      2
> >     ... value mask:             000000ffffffffff
> >     ... max period:             000000007fffffff
> >     ... fixed-purpose events:   3
> >     ... event mask:             0000000700000003
> >     NMI watchdog enabled, takes one hw-pmu counter.
> >     Booting Node   0, Processors  #1 #2 #3 Ok.
> >     Brought up 4 CPUs
> 
> Is fine too but should be clarified to something like:
> 
>      NMI watchdog enabled on all CPUs, permanently consumes one hw-PMU counter
> 
> (Please note the capitalization of 'PMU' as well.)

Ok.  I can modify that.

Cheers,
Don