RFR: JDK-8318636: Add jcmd to print annotated process memory map [v6]

[Johan Sjölen]

On Wed, 1 Nov 2023 10:13:03 GMT, Thomas Stuefe <stuefe at openjdk.org> wrote:

>> src/hotspot/share/nmt/memMapPrinter.cpp line 105:
>> 
>>> 103:       _ranges[_count - 1].to = to;
>>> 104:       return true;
>>> 105:     }
>> 
>> I'm pretty sure that the virtual memory tracker already gives you the minimal set of regions, have you observed this branch being taken?
>
> Yes, it resulted in a significant performance gain for a test run where I interleaved non-committed and committed memory of the same tag. I may have been mistaken, of course.

It being committed or reserved shouldn't matter (I assume non-committed = reserved), as committed just means that there's a pointer to the committed memory region in the reserved memory region. Well, all I can say is that I'm surprised.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16301#discussion_r1378643276