On Thu, 4 Sep 2025 14:19:06 GMT, Stefan Johansson <[email protected]> wrote:
> 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. This pull request has now been integrated. Changeset: 937e19e8 Author: Stefan Johansson <[email protected]> URL: https://git.openjdk.org/jdk/commit/937e19e86aab9194c363fb8709bbbc6dead0c391 Stats: 16 lines in 4 files changed: 12 ins; 1 del; 3 mod 8366780: Enhance ProcSmapsParser and Printer to handle THPeligible field Reviewed-by: stuefe, ayang ------------- PR: https://git.openjdk.org/jdk/pull/27098
