RFR: 8300732: Whitebox functions for Metaspace test should use byte size [v4]

[Ashutosh Mehra]

On Wed, 30 Oct 2024 19:21:30 GMT, Sonia Zaldana Calles <szaldana at openjdk.org> wrote:

>> Hi all, 
>> 
>> This PR addresses [8300732](https://bugs.openjdk.org/browse/JDK-8300732) switching Whitebox Metaspace test functions to use bytes as opposed to words. 
>> 
>> Testing: 
>> - [x] `test/hotspot/jtreg/runtime/Metaspace` tests pass. 
>> 
>> Thanks, 
>> Sonia
>
> Sonia Zaldana Calles has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains five commits:
> 
>  - Merge branch 'master' of github.com:openjdk/jdk into JDK-8300732
>  - Feedback - updating Unit.valueOf to direct access
>  - Hard coding values and adding Unit class
>  - whitebox changes based on feedback. Using is_aligned and asserts
>  - 8300732: Whitebox functions for Metaspace test should use byte size

Marked as reviewed by asmehra (Committer).

A couple of minor things, otherwise looks good.

src/hotspot/share/prims/whitebox.cpp line 1788:

> 1786: 
> 1787: WB_ENTRY(jlong, WB_RootChunkWordSize(JNIEnv* env))
> 1788: return (jlong)Metaspace::reserve_alignment_words();

indentation required

test/hotspot/jtreg/runtime/Metaspace/elastic/TestMetaspaceAllocationMT1.java line 109:

> 107: 
> 108:             // Note: reserve limit must be a multiple of Metaspace::reserve_alignment_words()
> 109:             //  (512K on 64bit, 1M on 32bit)

Are these figures still valid?
IIUC Metaspace::reserve_alignment_words() is 16M on 32-bit and 64M on 64-bit.

-------------

PR Review: https://git.openjdk.org/jdk/pull/20039#pullrequestreview-2416168758
PR Comment: https://git.openjdk.org/jdk/pull/20039#issuecomment-2457670809
PR Review Comment: https://git.openjdk.org/jdk/pull/20039#discussion_r1829679980
PR Review Comment: https://git.openjdk.org/jdk/pull/20039#discussion_r1829679868