RFR: JDK-8313781: Add regression tests for large page logging and user-facing error messages

[Stefan Johansson]

On Fri, 4 Aug 2023 14:33:02 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> In preparation for the UseSHM removal (https://bugs.openjdk.org/browse/JDK-8310841) I'd like more regression tests. 
> 
> The new test basically checks the behavior of the JVM when confronted with different variations of:
> - OS capabilities
> - JVM settings.
> 
> For example: If the JVM is started with -XX:+UseLargePages, but on the OS side there are no huge pages configured, or the kernel does not even support hugepages, the JVM should disable large pages and issue a warning.

Looks good, just one minor thing. 

I saw the comment about `LargePageSizeInBytes` and thought that it should be required away but realized that `ProcessTools.createJavaProcessBuilder()` doesn't add the passed in options.

Also did some manual runs on an aarch64 system where the default 512m pages are not configured but the 2m pages are. This seem to generate output which will be accepted by the test.

test/hotspot/jtreg/runtime/os/TestHugePageDecisionsAtVMStartup.java line 119:

> 117:         }
> 118: 
> 119:         else if (useLP && !useTHP &&

I would prefer skipping the empty lines here and below.
Suggestion:

        } else if (useLP && !useTHP &&

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Marked as reviewed by sjohanss (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/15159#pullrequestreview-1578435966
PR Review Comment: https://git.openjdk.org/jdk/pull/15159#discussion_r1294514721