RFR: 8310428: Add CollectedHeap::reserved_range() API to return reserved heap memory range

[Thomas Stüfe]

<snip>


> Maybe there are ways to rearrange the initialization order so that
> sub-systems that need to perform particular memory area reservation can be
> done before we reserve the heap? FWIW, ZGC can reserve discontiguous memory
> (See: ZVirtualMemoryManager::reserve_discontiguous) and can deal with
> memory areas being pre-reserved by other sub-systems.
>
>
No, I think the current order makes sense. For GCs that use compressed oops
and therefore benefit from having "good" heap ranges, GC reservation should
come first since the benefit of zero-based compressed oops is larger than
the one from zero-based narrow Klasses.


> StefanK
>
>
>
>> If not, and we really need to add this to
>> CollectedHeap for some reason, then I think reserved_range need to be
>> renamed to something that is bleeding obvious not going to be available
>> for all GCs.
>>
>> StefanK
>>
>>
> Thomas
>
>
>> >
>> > -------------
>> >
>> > PR Comment:
>> https://git.openjdk.org/jdk/pull/14595#issuecomment-1604898333
>>
>>
>
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