Re: Threaded irqs + 100% CPU RT task = RCU stall

[Paul Gortmaker <paul.gortmaker@windriver.com>]

On 13-03-06 10:58 AM, Thomas Gleixner wrote:
> On Wed, 6 Mar 2013, Paul Gortmaker wrote:
>> So, I guess the question is, whether we want to try and make the system
>> fail in a more meaningful way -- kind of like the rt throttling message
>> does - as it lets users know they've hit the wall?  Something watching
> 
> That Joe Doe should have noticed the throttler message, which came
> before the stall, shouldn't he?

Actually it isn't showing up at all -- just the RCU stall itself.
Now that you mention it, I do wonder why the throttler message 
isn't tripped though...

Paul.
--

> 
>> for kstat_incr_softirqs traffic perhaps?  Or other options?
> 
> The rcu stall detector could use the softirq counter and if it did not
> change in the stall period print: "Caused by softirq starvation" or
> something like that.
> 
> Thanks,
> 
> 	tglx
> 
>