Uncommit space on memory mapped heaps

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    • Type: Enhancement
    • Resolution: Unresolved
    • Priority: P4
    • tbd
    • Affects Version/s: 13
    • Component/s: hotspot
    • gc

      Since kernel 2.6.38 Linux has the capability to "uncommit" space in memory mapped files (FALLOC_FL_PUNCH_HOLE, http://man7.org/linux/man-pages/man2/fallocate.2.html).

      This would allow collectors mapping the Java heap from a file (via e.g. AllocateHeapAt) for e.g. providing Java heap on NVDIMM uncommit unused space.

      ZGC will also use this facility planned with JEP 351: ZGC: Uncommit Unused Memory, however it is useful for all collectors.

            Assignee:
            Unassigned
            Reporter:
            Thomas Schatzl
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              Created:
              Updated: