RFR: 8337217: Port VirtualMemoryTracker to use VMATree [v8]

[Robert Toyonaga]

On Mon, 9 Dec 2024 10:17:27 GMT, Afshin Zafari <azafari at openjdk.org> wrote:

>> src/hotspot/share/nmt/regionsTree.hpp line 105:
>> 
>>> 103:         if (prev.is_committed_begin()) {
>>> 104:           comm_size += curr.distance_from(prev);
>>> 105:           if (!curr.is_committed_begin()) {
>> 
>> Shouldn't it be impossible to have 2 back-to-back committed regions? Wouldn't they already be coalesced by `VMATree::register_mapping`?
>
> Only regions with the same `MemTag` can be merged into one. It is possible to have two adjacent committed regions with different `MemTag`s.

Ok I see. Thank you for clarifying.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/20425#discussion_r1876311697