Request for review: 8008546: G1: Wrong G1CONFIDENCEPERCENT results in GUARANTEE(VARIANCE() > -1.0) FAILED

vladimir kempik vladimir.kempik at
Wed Feb 20 15:27:40 UTC 2013

Hi Bengt,

Thanks for looking at this!

Here is an updated webrev based on your feedback:

I applied what you suggested.


On 20.02.2013 17:54, Bengt Rutisson wrote:
> Hi Vladimir,
> This looks very similar to how we treat G1ReservePercent, so I think 
> it looks good. An alternative would have been to check this earlier in 
> the initialization phase and update the flag G1ConfidencePercent so 
> that PrintFlagsFinal would have printed the actual value. But for 
> consistency I think it looks good this way.
> I think you can change G1ConfidencePercent to be an uintx instead of 
> intx (in g1_globals.hpp). In that case you don't need the second if 
> statment since it can't be less than 0. It is also more consistent 
> with G1ReservePercent which is an uintx.
> Thanks,
> Bengt
> On 2/20/13 2:31 PM, vladimir kempik wrote:
>> Hi all,
>> Could I have a couple of reviews for this change?
>> Input value for G1CONFIDENCEPERCENT wasn't checked before using. This 
>> results in crash sometimes if -XX:+UseG1GC 
>> -XX:G1ConfidencePercent=200 flags are used. Now checking the value 
>> same way as it was done for G1ReservePercent. Increase to 0 if 
>> negative, decrease to 100 if more than 100.
>> Thanks,
>> Vladimir

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