lkml.org 
[lkml]   [2010]   [Feb]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 3/3 v2] nmi_watchdog: config option to enable new nmi_watchdog
From
On 2/8/10, Ingo Molnar <mingo@elte.hu> wrote:
>
> * Don Zickus <dzickus@redhat.com> wrote:
>
>> +config NMI_WATCHDOG
>> + bool "Detect Hard Lockups with an NMI Watchdog"
>> + depends on DEBUG_KERNEL && PERF_EVENTS
>> + default y
>> + help
>> + Say Y here to enable the kernel to use the NMI as a watchdog
>> + to detect hard lockups. This is useful when a cpu hangs for no
>> + reason but can still respond to NMIs. A backtrace is displayed
>> + for reviewing and reporting.
>> +
>> + The overhead should be minimal, just an extra NMI every few
>> + seconds.
>
> Thought for later patches: I think an architecture should be able to express
> via a Kconfig switch that it actually _has_ NMI events. There's
> architectures
> which dont have a PMU driver and only have software events. There's also
> architectures that have a PMU driver but no NMIs.
>
> Something like ARCH_HAS_NMI_PERF_EVENTS?
>
> Also, i havent checked, but what is the practical effect of the new generic
> watchdog on x86 CPUs that does not have a native PMU driver yet - such as
> P4s?
>

p4 pmu is not yet implemented. I'll try to post on lkml the thnigs
i've done for it today evening, though it's pretty ugly i would say.

> Anyway, i'll create a tip:perf/nmi topic branch for these patches, it
> certainly looks like a useful generalization and a new architecture that has
> perf could easily enable it, without having to write its own NMI watchdog
> implementation. It's also useful for any new watchdog features that people
> might want to add. Plus it makes the x86 PMU code cleaner in the long run as
> well.
>
> Thanks,
>
> Ingo
>


\
 
 \ /
  Last update: 2010-02-08 10:49    [W:1.439 / U:0.200 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site