RFR: 8315149: Add hsperf counters for CPU time of internal GC threads [v27]

[Man Cao]

On Thu, 5 Oct 2023 03:00:36 GMT, Jonathan Joo <jjoo at openjdk.org> wrote:

>> 8315149: Add hsperf counters for CPU time of internal GC threads
>
> Jonathan Joo has updated the pull request incrementally with one additional commit since the last revision:
> 
>   add comment and change if defined to ifdef

test/jdk/sun/tools/jcmd/TestGcCounters.java line 17:

> 15: public class TestGcCounters {
> 16: 
> 17:     private static final String[] VM_ARGS = new String[] { "-XX:+UsePerfData" };

The `VM_ARGS` is passed to the jcmd subprocess via `JcmdBase.jcmd()`. This is probably not what we want, we want to pass `-XX:+UsePerfData` to the main process that runs `TestGcCounters.main()`.

We probably need this on line 13:

@run main/othervm -XX:+UsePerfData TestGcCounters

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PR Review Comment: https://git.openjdk.org/jdk/pull/15082#discussion_r1355941023