RFR: JDK-8293313: NMT: Rework MallocLimit [v2]

[Thomas Stuefe]

On Mon, 16 Jan 2023 14:27:05 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> Thomas Stuefe has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:
>> 
>>  - Merge branch 'master' into JDK-8293313-NMT-fake-oom
>>  - MallocLimit
>
> test/hotspot/jtreg/runtime/Unsafe/Reallocate.java line 65:
> 
>> 63:         // Make sure we can throw an OOME when we fail to reallocate due to OOM
>> 64:         try {
>> 65:             unsafe.reallocateMemory(address, 100 * 1024 * 1024);
> 
> Why are we changing the test here? Just because 800m is a lot larger than the required 100m?

MallocMaxTestWords took the value in *words*, that's where the 8 comes in. Note that it was broken anyway since it never shrank - it ignored free calls. Therefore the values given to MallocMaxTestWords have only ever been guesswork.

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PR: https://git.openjdk.org/jdk/pull/11371