RFR: 8078901: Add trace event for G1 MMU information

[Stefan Johansson]

I need one more reviewer before pushing.

Webrev with latest updates:
http://cr.openjdk.java.net/~sjohanss/8078901/hotspot.02/

Stefan

On 2015-06-30 13:14, Stefan Johansson wrote:
> Thanks Erik!
>
> Stefan
>
> On 2015-06-30 10:58, Erik Helin wrote:
>> On 2015-06-26, Stefan Johansson wrote:
>>> Thanks Erik for looking at this,
>>>
>>> On 2015-06-18 10:44, Erik Helin wrote:
>>>> Hi Stefan,
>>>>
>>>> sorry for not getting to this earlier, thanks a lot for this patch!
>>>>
>>>> On 2015-04-30, Stefan Johansson wrote:
>>>>> Hi,
>>>>>
>>>>> Please review this change to add a trace event for MMU tracking:
>>>>> https://bugs.openjdk.java.net/browse/JDK-8078901
>>>>>
>>>>> Webrev:
>>>>> http://cr.openjdk.java.net/~sjohanss/8078901/hotspot.00/
>>>> I have two comments:
>>>> - instead of using multiple inheritance, can you instead have the
>>>>    G1MMUTracer as a field in G1NewTracer and G1OldTracer? Then you can
>>>>    have a getter to the field.
>>>> - in G1MMUTracer, can you have the function report_mmu not take a
>>>>    G1MMUTracker* but instead have two additional double parameters, 
>>>> one
>>>>    for time_slice and one for max_gc_time? This way the tracers don't
>>>>    need to know about G1MMUTracker.
>>> Erik and I have discussed this a little more off-line and come to the
>>> conclusion to have an all-static class handling the the reporting of 
>>> the MMU
>>> event. This avoids the multiple inheritance and other problems of 
>>> having a
>>> G1MMUTracer as part of the other tracers. This solution slightly 
>>> differ from
>>> previously uses of the "tracers" but still keeps the code separated 
>>> in a
>>> good way.
>>>
>>> New webrev:
>>> http://cr.openjdk.java.net/~sjohanss/8078901/hotspot.01/
>> Looks good, Reviewed. As we discussed offline, please revert the changes
>> touching G1OldTracer and CMSTracer (no need to re-review that change).
>>
>> Thanks,
>> Erik
>>
>>> Thanks,
>>> Stefan
>>>> Thanks!
>>>> Erik
>>>>
>>>>> Summary:
>>>>> When adding pause information to the G1MMUTracker, it now reports a
>>>>> trace-event with the latest MMU information.
>>>>>
>>>>> add_pause() previously took a bool argument that was unused, but said
>>>>> whether or not it was a concurrent-cycle pause. I removed the bool 
>>>>> argument
>>>>> and added G1MMUTracer* argument. The G1MMUTracer is an interface 
>>>>> that both
>>>>> the stw-tracer and the cm-tracer now implement to make sure the 
>>>>> correct GC
>>>>> id is provided with the event.
>>>>>
>>>>> Thanks,
>>>>> Stefan
>