RFR: 8312132: Add tracking of multiple address spaces in NMT [v121]

[Johan Sjölen]

On Tue, 4 Jun 2024 05:30:19 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

> ZGC reserves virtual memory _before_ committing "physical" memory. Reporting the physical memory to also be "reserved" memory sounds misleading to me.

Good. We have an assert in NMT that `reserved >= committed`, so this is necessary for our tests to pass at least. This has no effect on production builds, of course.

I've fixed the code so that we report `MemoryFileTracker` memory as committed usage only in summary mode. I'm running tier1-tier3 in our CI system, which I expect will pass. Also, some additional manual testing. I'll integrate after everything is green.

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PR Comment: https://git.openjdk.org/jdk/pull/18289#issuecomment-2147421280