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  1. JDK
  2. JDK-8272773

Configurable card table card size

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    • gc
    • b25

    Description

      A card in the card table currently has a fixed constant size of 512 bytes for forever.

      This can impact pause time significantly in g1 as it needs to clear the young gen card table in the pause.

      If you increase the card table entry size, there may be significant savings on that time when the amount of regions the card table has to be cleared is large, as the attached spreadsheet shows for specjbb2015.

      See what the impact on other applications and garbage collectors is when increasing the card table size, effectively making it startup time configurable.

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          CSR - null JDK-8275142 Configurable card table card size

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed
          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8277854 The upper bound of GCCardSizeInBytes should be limited to 512 for 32-bit platforms

          • P2 - Crashes, loss of data, severe memory leak.
          • Closed

          Enhancement - null JDK-8277373 Make maximum card table size dependent on ObjectAlignmentInBytes

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Enhancement - null JDK-8277450 Record number of references into collection set during gc

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Enhancement - null JDK-8328364 Remove redundant fields in 'BOTConstants'

          • P5 - Cosmetic problem like misspelt words or misaligned text.
          • Resolved

          Enhancement - null JDK-8272774 Allow heap region sizes larger than 32M with larger card table entry sizes

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Closed

          Bug - A problem which impairs or prevents the functions of the product. JDK-8309627 Incorrect sorting of DirtyCardQueue buffers

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Enhancement - null JDK-8227174 Lazily set card table of allocated regions to correct values in G1

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Enhancement - null JDK-8278901 Parallel: Investigate impact of card size on card scanning work distribution

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Open

          Enhancement - null JDK-8275056 Virtualize G1CardSet containers over heap region

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved

          Enhancement - null JDK-8277372 Add getters for BOT and card table members

          • P4 - Minor loss of function, or other problem where easy workaround is present.
          • Resolved
          links to

          Commit Commit openjdk/jdk/1c215f33

          Review Review openjdk/jdk/5838

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              tschatzl Thomas Schatzl
              tschatzl Thomas Schatzl
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                Created:
                Updated:
                Resolved: