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

[Johan Sjölen]

On Fri, 24 May 2024 12:23:23 GMT, Johan Sjölen <jsjolen at openjdk.org> wrote:

>> src/hotspot/share/nmt/memoryFileTracker.cpp line 50:
>> 
>>> 48:   for (int i = 0; i < mt_number_of_types; i++) {
>>> 49:     VirtualMemory* summary = device->_summary.by_type(NMTUtil::index_to_flag(i));
>>> 50:     summary->reserve_memory(diff.flag[i].reserve);
>> 
>> Why do we only track reserved memory here?
>
> This is clearly a point of confusion, as Gerard also asked about this. The answer is that the MFT only cares about memory in a file, which is always considered committed... So we consider reserved memory to be committed. Yeah, let's just change it so that MFT always commits memory instead.

Switched it around a bit.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18289#discussion_r1613409163