Review request: 8025096: Move the ChunkManager instances out of the VirtualSpaceLists

[Jon Masamitsu]

Stefan,

Would you consider changing  _chunk_manager_class
to _chunk_manager_compressed_classes?  It is long but
it reminds me what exactly it is.

metaspace.cpp

651   size_t small_chunk_size() { return (size_t) is_class() ? ClassSmallChunk : SmallChunk; }

Can you have 3 arrays of chunks sizes

_specialized[] = {SpecializedChunk, SpecializedChunk}
_small_chunks[] = {ClassSmallChunk, SmallChunk}
_meduim_chunks[] = {ClassMediumChunk, MediumChunk}

and then the static

static size_t small_chunk_size() { return _small_chunks[_index_of_mdtype]; }


Does purge() work for compressed class space?

> void Metaspace::purge() {
>   MutexLockerEx cl(SpaceManager::expand_lock(),
>                    Mutex::_no_safepoint_check_flag);
>   purge(NonClassType);
>   if (using_class_space()) {
>     purge(ClassType);
>   }
> }

Is compressed class space still supported by a single VirtualSpace?
I think the idea behind purge() is to check for VirtualSpaces that are
filled with unused chunks and release the VirtualSpace.

Jon


On 9/19/2013 11:54 PM, Stefan Karlsson wrote:
> http://cr.openjdk.java.net/~stefank/8025096/webrev.01/
>
> New webrev based on Coleen's comments.
>
> Changes:
> - Moved the _vs_list pointer out from SpaceManager
> - Removed the unused _medium_chunk_bunch field.
>
> thanks,
> StefanK
>
> On 9/19/13 9:48 PM, Stefan Karlsson wrote:
>> http://cr.openjdk.java.net/~stefank/8025096/webrev.00/
>> https://bugs.openjdk.java.net/browse/JDK-8025096
>>
>> In the fix for 'JDK-8024547 
>> <https://bugs.openjdk.java.net/browse/JDK-8024547>: MaxMetaspaceSize 
>> should limit the committed memory used by the metaspaces' we need to 
>> make a clearer distinction between when new memory is committed and 
>> when memory is allocated inside already committed memory.
>>
>> Moving the ChunkManager, which handles the free chunk list, out of 
>> the VirtualSpaceList, which handles the committed metaspace memory, 
>> is a step in that direction.
>>
>> Changes:
>> - Move the ChunkManager instances from VirtualSpaceList to SpaceManager.
>> - Move the inc_container_count() into ChunkManager::free_chunks_get. 
>> Now the Chunk manager calls dec_container_count when chunks are 
>> inserted in the chunk free list and inc_container_count when chunks 
>> are removed from the chunk free list.
>> - Moved the ChunkManager::chunk_freelist_allocate() call out from the 
>> VirtualSpaceList::get_new_chunk()
>>
>> thanks,
>> StefanK
>