JDK-8366780 : Enhance ProcSmapsParser and Printer to handle THPeligible field
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: 26
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2025-09-03
  • Updated: 2025-09-25
  • Resolved: 2025-09-19
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JDK 26
26 b17Fixed
Related Reports
Relates :  
JDK-8322475 - Extend printing for System.map
Description
While working on 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. 

It might make sense to only print the new THP tag if "thpad" (for THP advised mapping) is not included to avoid too many THP tags.
Comments
Changeset: 937e19e8 Branch: master Author: Stefan Johansson <sjohanss@openjdk.org> Date: 2025-09-19 08:48:35 +0000 URL: https://git.openjdk.org/jdk/commit/937e19e86aab9194c363fb8709bbbc6dead0c391
19-09-2025
A pull request was submitted for review. Branch: master URL: https://git.openjdk.org/jdk/pull/27098 Date: 2025-09-04 14:19:06 +0000
04-09-2025