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  1. JDK
  2. JDK-8224182

[Performance] sun.misc.Unsafe.[put|get]* suffer from redundant memory barriers

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    • x86_64
    • linux_ubuntu

    Description

      A DESCRIPTION OF THE PROBLEM :
      jdk.internal.misc.Unsafe implements methods to read/write native memory in following fashion:
      @ForceInline
      public byte getByte(long address) {
           return getByte(null, address);
      }
      As can be seen, a null value is passed on the stack without a reason.
      To resolve this, the method should be defined as:
      @HotSpotIntrinsicCandidate
       public native byte getByte(long offset);

      The reason to resolve this is because the current implementation is slower than the older one in eg. Java 8.


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          duplicates

          Bug - A problem which impairs or prevents the functions of the product. JDK-8226396 C2: Redundant address computations for array accesses

          • P3 - Major loss of function.
          • Open

          Enhancement - null JDK-8226409 Enable argument profiling for sun.misc.Unsafe.put*/get*

          • P3 - Major loss of function.
          • Resolved

          Enhancement - null JDK-8226411 C2: Avoid memory barriers around off-heap unsafe accesses

          • P3 - Major loss of function.
          • Resolved
          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8226396 C2: Redundant address computations for array accesses

          • P3 - Major loss of function.
          • Open

          Bug - A problem which impairs or prevents the functions of the product. JDK-8176506 C2: loop unswitching and unsafe accesses cause crash

          • P3 - Major loss of function.
          • Resolved

          Enhancement - null JDK-8181211 C2: Use profiling data to optimize on/off heap unsafe accesses

          • P3 - Major loss of function.
          • Resolved

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              vlivanov Vladimir Ivanov
              webbuggrp Webbug Group
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              Dates

                Created:
                Updated:
                Resolved: