RFR: 8253779: Amalloc may be wasting space by overaligning [v2]

[Thomas Stuefe]

On Fri, 9 Jul 2021 01:25:15 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Thanks to @kimbarrett for noticing this. The alignment was changed to 64 bits for 32 bit platforms, but overalign for 64 bits platforms.  I changed this to BytesPerLong to cover both, since the long case is why it was changed on 32 bits in the first place in JDK-4526490.
>> I also removed Amalloc_D since I don't know what D stands for and it's the same as Amalloc_4.  That's not a great name either. I'm open to suggestions!
>> Tested with tier1-3.
>
> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Improvements ala Kim

One thought, maybe it should keep the alignment adjustable with a diagnostic switch in debug. At least for a little while. Since we may uncover hidden overwrite issues with the reduced alignment.

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PR: https://git.openjdk.java.net/jdk/pull/4732