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

Ingo Molnar
2012-06-11T08:47:51Z

* 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