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  1. JDK
  2. JDK-8241486

G1/Z give warning when using LoopStripMiningIter and turn off LoopStripMiningIter (0)

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    • Subcomponent:
    • Introduced In Build:
      b36
    • Introduced In Version:
      10
    • Resolved In Build:
      b14

      Description

      I tested setting the LoopStripMiningIter which complained that UseCountedLoopSafepoints is off:

      Java HotSpot(TM) 64-Bit Server VM warning: Disabling counted safepoints implies no loop strip mining: setting LoopStripMiningIter to 0

      In g1Arguments.cpp G1Arguments::initialize()
      We do:
      #ifdef COMPILER2
        // Enable loop strip mining to offer better pause time guarantees
        if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {

      We should not give a warning and turn LoopStripMiningIter off.

      [rehn@rehn-ws dev-jdk]$ java -XX:+PrintFlagsFinal -version | grep "Strip\|UseCountedLoopSafepoints"
          uintx LoopStripMiningIter = 1000 {C2 product} {default}
          uintx LoopStripMiningIterShortLoop = 100 {C2 product} {default}
           bool UseCountedLoopSafepoints = true {C2 product} {default}

      [rehn@rehn-ws dev-jdk]$ java -XX:LoopStripMiningIter=100 -XX:+PrintFlagsFinal -version | grep "Strip\|UseCountedLoopSafepoints"
      OpenJDK 64-Bit Server VM warning: Disabling counted safepoints implies no loop strip mining: setting LoopStripMiningIter to 0
          uintx LoopStripMiningIter = 0 {C2 product} {command line}
          uintx LoopStripMiningIterShortLoop = 0 {C2 product} {default}
           bool UseCountedLoopSafepoints = true {C2 product} {default}

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              • Assignee:
                roland Roland Westrelin
                Reporter:
                rehn Robbin Ehn
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