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  1. JDK
  2. JDK-8278396

G1: Initialize the BOT threshold to be region bottom

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 18
    • Fix Version/s: 19
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
      gc
    • Resolved In Build:
      master

      Description

      The threshold is initialized to be the start of *second* card. The rational here is that objects are allocated from the region-start (except for humongous-continue regions), so the entry for the first card will always be zero.

      ```
      void G1BlockOffsetTablePart::initialize_threshold() {
        _next_offset_threshold = _hr->bottom() + BOTConstants::card_size_in_words();
      }
      ```

      Instead, one can use `bottom()` as the initial value; then entries for offset cards (cards holding the offset value, in constrast to cards holding backskip values) will be strictly less than card size.

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              Assignee:
              ayang Albert Yang
              Reporter:
              ayang Albert Yang
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                Updated:
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