RFR: 8316813: NMT: Using WhiteBox API, virtual memory tracking should also be stressed in JMH tests

[Johan Sjölen]

On Fri, 26 Jan 2024 08:52:51 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

> After WhiteBox (`wb.jar`) is added to the lib-test, it is possible to use it in Java benchmarks. This PR uses WhiteBox to access and call directly NMT API and measure their performance in stressed circumstances.

Hi,

A couple of comments, looks good in general.

test/micro/org/openjdk/bench/vm/runtime/NMTBenchmark_wb.java line 63:

> 61:     public int SUB_REGIONS;
> 62: 
> 63:     private static final int P = 1024 * 4;

Better name please!

test/micro/org/openjdk/bench/vm/runtime/NMTBenchmark_wb.java line 80:

> 78:                 t.printStackTrace();
> 79:                 // Explicit exit to avoid initialization loops.
> 80:                 System.exit(17);

What's this exit code?

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PR Review: https://git.openjdk.org/jdk/pull/17582#pullrequestreview-1856305893
PR Review Comment: https://git.openjdk.org/jdk/pull/17582#discussion_r1474336509
PR Review Comment: https://git.openjdk.org/jdk/pull/17582#discussion_r1474341243