> Please review this enhancement to the smaps parser and printer.
> 
> **Summary**
> While working on [JDK-8366434](https://bugs.openjdk.org/browse/JDK-8366434) 
> one idea for a test to verify if the heap CAN be backed by transparent huge 
> pages (THP) was to use PrintMemoryMapAtExit and look at the tags printed for 
> JAVAHEAP.
> 
> It turns out this worked in most cases but on systems where the THP mode is 
> configured as 'always' but there are no huge pages available for use, the 
> JAVAHEAP line will not show any indication that it can be backed by huge 
> pages.
> 
> For this to be possible we need to parse the field THPeligible as well and 
> include this information in the printouts. With this change we now parse the 
> THPeligible field and tag mapping that are THP eligible with `thpel`. We skip 
> this tag for mappings that are tagged with `thpad` (madvised with 
> MADV_HUGEPAGE) to avoid too much THP info on one mapping.
> 
> **Testing**
> * Mach5 testing with the existing test showed a need to update the regex for 
> verifying Metaspace and the fix have been tested manually locally as well as 
> in Mach5.

Stefan Johansson has updated the pull request incrementally with one additional 
commit since the last revision:

  Offline comments and discussion

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/27098/files
  - new: https://git.openjdk.org/jdk/pull/27098/files/521afbad..d9aa3c29

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27098&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27098&range=01-02

  Stats: 4 lines in 1 file changed: 2 ins; 2 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27098.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27098/head:pull/27098

PR: https://git.openjdk.org/jdk/pull/27098

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