RFR: 8312132: Add tracking of multiple address spaces in NMT [v105]

[Johan Sjölen]

On Sat, 25 May 2024 06:01:58 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> Switched it around a bit.
>
> For the purpose of consistency with the rest of NMT, and to be able to use normal VirtualSummary etc, maybe MFT should mark the whole range as reserved upfront?

I don't think that's the right choice here as the typical use-case is probably that you:

1. Reserve memory in the virtual address space
2. Make a memory file
3. Map in memory from that file to the memory you previously reserved

So if the memory file is also reserved, then that would cause "double accounting" of sorts. I'm also not sure if you have equivalent semantics of reserved memory for temporary files (doesn't actually take up space, is non-writeable).

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PR Review Comment: https://git.openjdk.org/jdk/pull/18289#discussion_r1614467229