RFR(M): 8155634: Clean out old logging and dead code from SurvRateGroup

[Mikael Gerdin]

Hi Jon,

On 2016-05-02 20:58, Jon Masamitsu wrote:
>
> On 05/02/2016 05:40 AM, Mikael Gerdin wrote:
>> Hi,
>>
>> Please review this change to clean out unused code from SurvRateGroup.
>> The G1YoungSurvRateNumRegionsSummary flag is only accessible in
>> notproduct builds and it is my opinion that the ability to print the
>> predicted aggregate survivor rates for eden regions at JVM shutdown is
>> not a particularly useful feature.
>>
>> Testing: Local testing with gc test suite.
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8155634
>> Webrev: http://cr.openjdk.java.net/~mgerdin/8155634/webrev.0/
>
> Mikael,
>
> Changes look good.

Thanks.

>
> I don't have much of an opinion on whether the survivor rate summary is
> useful but I note that
>
> http://cr.openjdk.java.net/~mgerdin/8155634/webrev.0/src/share/vm/gc/g1/g1CollectedHeap.cpp.udiff.html
>
>   void G1CollectedHeap::print_tracing_info() const {
>     g1_rem_set()->print_summary_info();
>     concurrent_mark()->print_summary_info();
> - g1_policy()->print_yg_surv_rate_info();
>   }
>
> the remembered set and concurrent marking summaries are being kept.
> Can you explain why survivor rate is the exception?  All seems to
> me averages over such an extended period that they all deserve the
> same fate.

The reason is simply that I wanted to clean up how SurvRateGroups were 
used but understanding which parts of the class actually did some work 
was extremely difficult due to the fact that 50% of the code was only 
there to facilitate the logging.

In general I think we should remove the other summary infos as well but 
from my end this is more on an as-needed effort than a focused cleanup 
of these summary info outputs.

I don't think I have the cycles to get rid of the others before FC so I 
expect that the remaining ones will have to wait for the next release.

/Mikael

>
> Thanks.
>
> Jon
>
>
>>
>> /Mikael
>