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  1. JDK
  2. JDK-8213108

Improve work distribution during remembered set scan

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    • gc
    • b04

    Description

      Currently, during remembered set scan every thread may iterate over all cards in the remembered set of a given region; distribution across threads occurs by threads claiming cards N to N+x, and only trying to iterate over these cards.

      To avoid scanning the same card multiple times, G1 marks the already scanned cards in card table.

      One alternative is to for all regions collect the PRTs, and every thread claim part of that region's entire range of cards, building a small local bitmap of cards to scan using the PRTs for that region.

      This ensures that every card is only scanned once during Scan RS, avoids the need for all threads to iterate over all cards of a given region at the cost of small pre-initialization costs.

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        Issue Links

          blocks

          Enhancement - null JDK-8224759 Investigate block splitting during heap root scan

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

          Enhancement - null JDK-8224741 Optimize the scan area during the Scan Heap Roots phase

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

          Enhancement - null JDK-8224840 Optimize G1CardTable::mark_region_table()

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

          Bug - A problem which impairs or prevents the functions of the product. JDK-8218387 JFR TestG1ParallelPhases.java failed

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

          Enhancement - null JDK-8142950 Refactor G1 YC preparation code

          • P3 - Major loss of function.
          • Closed
          is blocked by

          Enhancement - null JDK-8224160 Move G1RemSetScanClosure into g1RemSet.cpp file

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

          Bug - A problem which impairs or prevents the functions of the product. JDK-8278824 Uneven work distribution when scanning heap roots in G1

          • P3 - Major loss of function.
          • Resolved

          Bug - A problem which impairs or prevents the functions of the product. JDK-8218387 JFR TestG1ParallelPhases.java failed

          • 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-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-8226232 Move merge heap roots code out from G1RemSetScanState

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

          Enhancement - null JDK-8226913 Scale cards per chunk used during heap root scanning with region size

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

          Bug - A problem which impairs or prevents the functions of the product. JDK-8227090 G1 does not account the OptMergeRS in cost per card calculation

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

          Enhancement - null JDK-8017163 G1: Refactor remembered sets

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

          Enhancement - null JDK-8200545 Improve filter for enqueued deferred cards

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

          Enhancement - null JDK-8227084 Add timing information for merge heap root preparation

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

          Enhancement - null JDK-8227089 Add timing information for merging humongous remembered sets

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

          Enhancement - null JDK-8227739 Merge cost predictions for scanning cards and log buffer entries

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

          Enhancement - null JDK-8231553 Deprecate unused G1RSetScanBlockSize command line option

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

          Enhancement - null JDK-8304055 G1: Remove OldGCAllocRegion::release

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

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              tschatzl Thomas Schatzl
              tschatzl Thomas Schatzl
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              Dates

                Created:
                Updated:
                Resolved: