RFR: mmap connection matrix

[Aleksey Shipilev]

On 05/22/2017 12:11 PM, Roman Kennke wrote:
> Am 22.05.2017 um 11:41 schrieb Aleksey Shipilev:
>> Hi,
>>
>> Currently the connection matrix is allocated in C heap. We can make it
>> consistent with marking bitmaps by mmap-ing the matrix as well:
>>  http://cr.openjdk.java.net/~shade/shenandoah/matrix-mmap/webrev.01/
>>
>> Testing: hotspot_gc_shenandoah
>>
>> -Aleksey
>>
> It seems ugly that the allocation of the matrix is outside the
> ConnectionMatrix class. ShenandoahHeap now needs knowledge about
> internals of ConnectionMatrix.

There is already a fair amount of cohesion between ShMatrix and ShHeap. This
change makes ShMatrix the "view" over naked bitmap allocated in ShHeap.

Consider the upside: matrix can now be allocated with proper page sizes and
alignment.

-Aleksey