RFR: JDK-8307356: Metaspace: simplify BinList handling [v3]

[Thomas Stuefe]

On Tue, 23 May 2023 15:37:52 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Feedback David
>
> src/hotspot/share/memory/metaspace/metaspaceArena.cpp line 382:
> 
>> 380:   assert_is_aligned_metaspace_pointer(p);
>> 381:   size_t raw_word_size = get_raw_word_size_for_requested_word_size(word_size);
>> 382: 
> 
> If this is deallocating a pointer returned from metaspace, why isn't raw_word_size the same as word_size?

This only matters for 32-bit. 

There, we align allocation size to 2 words (64 bits). If someone deallocates a pointer to, say, 3 words (12 bytes), Metaspace knows that the block is really 16 bytes long and that is what we should store in the freelist.

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PR Review Comment: https://git.openjdk.org/jdk/pull/13776#discussion_r1297120916