RFR: 8256181: Remove Allocation of old generation on alternate memory devices functionality

[Albert Mingkun Yang]

On Wed, 11 Nov 2020 11:11:25 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   can I get reviews for this change that removes the "Allocation of old generation of Java heap on alternate memory devices" functionality introduced with JDK 12 with [JDK-8202286](https://bugs.openjdk.java.net/browse/JDK-8202286) due to being
> 
> - not used by anyone
> - not maintained by anyone, i.e. several bugs open for a long time and bit rotting
> - requiring some workarounds for new feature development wrt to heap management
> 
> All flags covered by this feature were experimental flags, so there are no additional procedural issues to take.
> 
> I tried to remove all but a few minor cleanups that I thought useful, but of course this is very subjective.
> 
> Testing: hs-tier1-5

A general comment for future PRs: I think it's best to isolate mechanical changes into their own commits; e.g. `HeapRegionManager* _hrm;` -> `HeapRegionManager _hrm;`. Otherwise, a real change, buried in the immense size of diff, might slip through.

test/hotspot/jtreg/TEST.ROOT line 78:

> 76:     vm.musl \
> 77:     docker.support \
> 78:     test.vm.gc.nvdimm \

`test/jtreg-ext/requires/VMProps.java` still references `test.vm.gc.nvdimm`, btw.

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Marked as reviewed by ayang (Author).

PR: https://git.openjdk.java.net/jdk/pull/1162