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  1. JDK
  2. JDK-8216975

Using ForceNUMA does not disable adaptive sizing with parallel gc

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    Details

    • Type: Bug
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 13
    • Fix Version/s: 15
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • Resolved In Build:
      b12

      Description

      Following code in os_linux.cpp in os::init_2() indicates that NUMA and adaptive sizing is incompatible with parallel gc:

          if (UseParallelGC && UseNUMA && UseLargePages && !can_commit_large_page_memory()) {
            // With SHM and HugeTLBFS large pages we cannot uncommit a page, so there's no way
            // we can make the adaptive lgrp chunk resizing work. If the user specified both
            // UseNUMA and UseLargePages (or UseSHM/UseHugeTLBFS) on the command line - warn
            // and disable adaptive resizing.
            if (UseAdaptiveSizePolicy || UseAdaptiveNUMAChunkSizing) {
              warning("UseNUMA is not fully compatible with SHM/HugeTLBFS large pages, "
                      "disabling adaptive resizing (-XX:-UseAdaptiveSizePolicy -XX:-UseAdaptiveNUMAChunkSizing)");
              UseAdaptiveSizePolicy = false;
              UseAdaptiveNUMAChunkSizing = false;
            }
          }


      However a few lines of code later, if ForceNUMA is set, we unconditionally set UseNUMA to true.

      Investigate this contradiction.

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            Assignee:
            iwalulya Ivan Walulya
            Reporter:
            tschatzl Thomas Schatzl
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