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  1. JDK
  2. JDK-8266821

G1: Prefetch cards during merge heap roots phase

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 17
    • Fix Version/s: 17
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • Resolved In Build:
      b23

      Description

      Merging heap roots (remembered sets and log buffers) into the card table for later scanning to a large degree constitutes random accesses to the card table.

      Putting a small prefetch queue between calculating the card table address and inspecting the given card table value decreases merge remembered set time by 20-30% and merge log buffers time by 40-50% (on x64. AArch64 shows similar if not better improvements).

      Applications not having a significant amount of either remembered sets or log buffers do not show significant difference.

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              Assignee:
              tschatzl Thomas Schatzl
              Reporter:
              tschatzl Thomas Schatzl
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