RFR: 8155245: Add logging when MMU target is violated

[Erik Helin]

On 2016-04-27, Stefan Johansson wrote:
> Hi,
> 
> Please review this small change to add logging for MMU violations:
> https://bugs.openjdk.java.net/browse/JDK-8155245
> 
> Webrev:
> http://cr.openjdk.java.net/~sjohanss/8155245/hotspot.00/

Looks good, Reviewed.

Thanks,
Erik

> Summary:
> Add a log line when spending more time then allowed in GC, also added a new
> tag "mmu" and made sure it is associated with the GC-id.
> 
> Testing:
> JPRT
> 
> Thanks,
> Stefan