Please review fix for 7196103: NPG: Unable to allocate bit map for parallel garbage collection for the requested heap size

[Coleen Phillimore]

On 9/7/2012 10:52 AM, Jon Masamitsu wrote:
> Coleen,
>
> Could you just enforce this with code instead of an assertion?
> I don't want to see that assertion in tomorrow's nightlies :-)

Me neither.  I fixed this as suggested.  The minimal ClassMetaspaceSize 
is 1*M which is always greater than 5 MediumChunks, but now it's safer 
if someone changes something.
>
> *+     assert(class_word_size<  ClassMetaspaceSize/2, "should be no 
> more then half class metaspace size");*
>
> class_word_size = 
> MIN2(**size_t)SpaceManager::MediumChunk*5,****ClassMetaspaceSize/2**)
>
> ClassMetaspaceSize is used to reserve space?  I see that it's not used
> for the initial Metaspace size.

No, these numbers are independent.

Thanks,
Coleen
>
> Otherwise, looks good.
>
> Jon
>
> On 9/7/2012 6:33 AM, Coleen Phillimore wrote:
>>
>> Please reload.  I incorporated some suggestions and corrections from 
>> stefank and did some tuning of the class metaspace size.
>>
>> Thanks,
>> Coleen
>>
>> On 9/7/2012 7:22 AM, Coleen Phillimore wrote:
>>> Summary: Don't allocate huge class metaspace size by default on x64
>>>
>>> This was preventing other mmap regions from being initialized on 
>>> windows 64.  I also added some checking around the 
>>> ClassMetaspaceSize option.  1*M seems to be minimal for startup size
>>>
>>> open webrev at http://cr.openjdk.java.net/~coleenp/7196103/
>>>
>>> Thanks,
>>> Coleen
>>>
>>>