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  1. JDK
  2. JDK-8225409

G1: Remove the Hot Card Cache

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Details

    • Enhancement
    • Status: Resolved
    • P4
    • Resolution: Fixed
    • 13
    • 21
    • hotspot
    • gc
    • b10

    Description

      The purpose of the Hot Card Cache is to collect often dirtied cards during mutator time.

      Anecdotal evidence indicates that the HCC does not contribute meaningfully to performance because:
      - it is very small (JDK-8135064); an application doing lots of refinement will overflow it quickly
      - an application doing little refinement will not use it

      However its data structures use a card map across the whole heap, i.e. one byte per card, which is 0.2% of the heap. That memory could be used more usefully in other places.

      Test and investigate its usefulness, also taking the concerns for JDK-8135064 into account.

      There may also be better ways that use less memory to cause the same effect.

      Attachments

        Issue Links

          csr for

          CSR - null JDK-8301965 G1: Remove the Hot Card Cache

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

          Enhancement - null JDK-8135064 Scale hot card cache size with heap size

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

          Enhancement - null JDK-8294753 Document why G1CardCounts::add_card_count is not thread-safe

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

          Bug - A problem which impairs or prevents the functions of the product. JDK-8225406 Account for hot card cache cards in distributing heap root scan times

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

          Enhancement - null JDK-8135064 Scale hot card cache size with heap size

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

          Commit Commit openjdk/jdk/7c50ab16

          Review Review openjdk/jdk/12452

          Activity

            People

              ayang Albert Yang
              tschatzl Thomas Schatzl
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              Dates

                Created:
                Updated:
                Resolved: