Re: [patch 1/2] Ignore stolen time in the softlockup watchdog

[Prarit Bhargava <prarit@redhat.com>]

Jeremy Fitzhardinge wrote:
> Prarit Bhargava wrote:
>   
>> I'd like to see this patch implement/fix touch_cpu_softlockup_watchdog
>> and touch_softlockup_watchdog to mimic touch_nmi_watchdog's behaviour.
>>     
>
> Why?  Is that more correct?  It seems to me that you're interested in
> whether a specific CPU has gone and locked up.  If touching the watchdog
>   
> makes it update all CPU timestamps, then you'll hide the fact that other
> CPUs have locked up, won't it?
>
>   
In case of misuse, yes.  But there are cases where we know that all CPUs 
will have softlockup issues, such as when doing a "big" sysrq-t dump.  
When doing the sysrq-t we take the tasklist_lock which prevents all 
other CPUs from scheduling -- this leads to bogus softlockup messages, 
so we need to reset everyone's watchdog just before releasing the 
tasklist_lock.

Another question -- are you going to expose disable/enable_watchdog to 
other subsystems?  Or are you going to expose touch_softlockup_watchdog?

>     J
>