request for review (s) - 8005452: Create new flags for Metaspace resizing policy

[Jon Masamitsu]

Updated for the latest review comments.

8005452: NPG: Create new flags for Metaspace resizing policy

I've change the default value of MinMetaspaceFreeRatio and
MaxMetaspaceFreeRatio so that they have the values of
MinHeapFreeRatio and MaxHeapFreeRatio, respectively.  That makes the
values  used by NPG unchanged.  I need to do more performance
work to justify a change.

http://cr.openjdk.java.net/~jmasa/8005452/webrev.04/

8006815: NPG: Trigger a GC for metadata collection just before the 
threshold is exceeded.

http://cr.openjdk.java.net/~jmasa/8006815/webrev.02/


On 01/25/13 15:50, Jon Masamitsu wrote:
> I've update the webrev2 (now 2 separate webrevs)  for review comments.
>
> 8005452: NPG: Create new flags for Metaspace resizing policy
>
> http://cr.openjdk.java.net/~jmasa/8005452/webrev.03/
>
> 8006815: NPG: Trigger a GC for metadata collection just before the 
> threshold is exceeded.
>
> http://cr.openjdk.java.net/~jmasa/8006815/webrev.01/
>
>
> On 1/16/2013 8:50 AM, Jon Masamitsu wrote:
>> I've added checks to arguments.cpp that are analogous to the
>> checks for MinHeapFreeRatio / MaxHeapFreeRatio
>>
>> Changes since webrev.00 are in arguments.cpp
>>
>> http://cr.openjdk.java.net/~jmasa/8005452/webrev.01/
>>
>> Thanks, Vitaly.
>>
>> Jon
>>
>> On 1/15/2013 5:55 AM, Vitaly Davidovich wrote:
>>> Hi Jon,
>>>
>>> Does it make sense to validate that the new flags are consistent 
>>> (I.e. max
>>>> = min)? That is, if user changes one or both such that max<  min, 
>>>> should
>>> VM report an error and not start?
>>>
>>> Thanks
>>>
>>> Sent from my phone
>>> On Jan 14, 2013 10:31 AM, "Jon Masamitsu"<jon.masamitsu at oracle.com>  
>>> wrote:
>>>
>>>> 8005452: Create new flags for Metaspace resizing policy
>>>>
>>>> Previously the calculation of the metadata capacity at which
>>>> to do a GC (high water mark, HWM) to recover
>>>> unloaded classes used the MinHeapFreeRatio
>>>> and MaxHeapFreeRatio to decide on the next HWM.  That
>>>> generally left an excessive amount of unused capacity for
>>>> metadata.  This change adds specific flags for metadata
>>>> capacity with defaults more conservative in terms of
>>>> unused capacity.
>>>>
>>>> Added an additional check for doing a GC before expanding
>>>> the metadata capacity.  Required adding a new parameter to
>>>> get_new_chunk().
>>>>
>>>> Added some additional diagnostic prints.
>>>>
>>>> http://cr.openjdk.java.net/~**jmasa/8005452/webrev.00/<http://cr.openjdk.java.net/~jmasa/8005452/webrev.00/> 
>>>>
>>>>
>>>> Thanks.
>>>>