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  1. JDK
  2. JDK-6916623

Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb

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    • Enhancement
    • Resolution: Fixed
    • P5
    • hs19
    • hs17
    • hotspot
    • b03
    • sparc
    • solaris_10
    • Verified

    Backports

      Description

        Whenever we decide to use Compressed Oops with 64Gb heap AT LEAST next changes should be made to build VM which support it.
        Note: more complex changes needed to use a VM option. I don't see benefits on N2 with it so I am putting it on shelf.

        src/share/vm/utilities/globalDefinitions.hpp
        @@ -288,11 +288,11
         // Minimum is max(BytesPerLong, BytesPerDouble, BytesPerOop) / HeapWordSize, so jlong, jdouble and
         // reference fields can be naturally aligned.
         
        -const int MinObjAlignment = HeapWordsPerLong;
        +const int MinObjAlignment = HeapWordsPerLong * 2; // *2 for 16 bytes alignment
         const int MinObjAlignmentInBytes = MinObjAlignment * HeapWordSize;
         const int MinObjAlignmentInBytesMask = MinObjAlignmentInBytes - 1;
         
        -const int LogMinObjAlignment = LogHeapWordsPerLong;
        +const int LogMinObjAlignment = LogHeapWordsPerLong + 1; // +1 for 16 bytes alignment
         const int LogMinObjAlignmentInBytes = LogMinObjAlignment + LogHeapWordSize;

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            backported by

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-2197578 Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb

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

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-2197872 Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb

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

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-2199772 Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb

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

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-2195070 Align object to 16 bytes to use Compressed Oops with java heap up to 64Gb

            • P5 - Cosmetic problem like misspelt words or misaligned text.
            • Closed
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-6957882 nsk/sajdi tests failed with NullPointerException

            • 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-6979458 VM crashes when -XX:ObjectAlignmentInBytes is too big

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

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                kvn Vladimir Kozlov
                kvn Vladimir Kozlov
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