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  1. JDK
  2. JDK-8261500

Shenandoah: reconsider region live data memory ordering

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 8-shenandoah, 11.0.9, 16, 17
    • Fix Version/s: 17
    • Component/s: hotspot
    • Subcomponent:
      gc
    • Resolved In Build:
      b10

      Description

      Current Shenandoah region live data tracking uses default CAS updates to achieve atomicity of updates. Hotspot's default for atomic operations is memory_order_conservative, which emits two-way memory fences around the CASes at least on AArch64 and PPC64.

      This seems to be excessive for live data tracking, and "relaxed" could be used instead. The only serious user of that data is collection set chooser, which runs at safepoint and so everything should be quiescent when that happens.

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              Assignee:
              shade Aleksey Shipilev
              Reporter:
              shade Aleksey Shipilev
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                Updated:
                Resolved: