RFR: 8157023: Integrate NMT with JFR [v2]

[Thomas Stuefe]

On Fri, 2 Dec 2022 15:41:04 GMT, Stefan Johansson <sjohanss at openjdk.org> wrote:

> Pushed some changes inspired by the discussion here. Not all things have been handled, but I think this is a step in the right direction.
> 
>     * The baseline is re-used if newer than 50ms, so if the two events are configured to occur with the same period they should be using the same baseline. I also save the  time of the baseline and use that in all events using that baseline.

I did some tests and on my box probing 20k threads - if we get ThreadCritical right away - takes about 50-100ms.

> 
>     * I swapped the event-names, or rather `NativeMemoryUsage` is not the event with a type, and we instead have `NativeMemoryUsageTotal` for the total event. This way we don't have to come up with something better for "part", and "total" is good.
> 
>     * Also move the JFR-reporting to its own file to get better separation.
> 

I like this, thank you.

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PR: https://git.openjdk.org/jdk/pull/11449