RFR: 8351661: NMT: VMATree should support separate call-stacks for reserve and commit operations [v25]

[Afshin Zafari]

On Wed, 14 May 2025 15:04:58 GMT, Gerard Ziemski <gziemski at openjdk.org> wrote:

>> There are a few questions/concerns to use this new output:
>> - the range of regions in tree may be 100-1000, then we need 1000 columns in print
>> - not all the regions are used within that range, e.g., only 10-20 and 900-1000 are used. 
>> - when we use `print_on` for debugging a real tree, the ranges are 16 hexadecimal digits, it would be hard to show them efficiently
>> 
>> I can add this visualization format to the test cases without changing the `print_on`. Is that OK?
>
> Sure, let's see it.
> 
> Also, we can always change the ranges of our specific test cases to be kept [0..100] to make the print outs happy, can't we?

In [this](https://github.com/openjdk/jdk/pull/24028/commits/831c1159e21d740f85e523ca745726ec4701f657) commit, I impl an example of the new format for one test case "SeparateStacksForCommitAndReserve". IMHO, your previous suggestion for the format ( using '*', '-', '/' for states) is more readable than this new one with letters and legend. 
Which one is preferred?

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PR Review Comment: https://git.openjdk.org/jdk/pull/24028#discussion_r2090726096