(original) (raw)
hi, everyone!
I have some question about the jdk 1.7 compiler.
According to the source code of "hotspot\\src\\share\\vm\\interpreter\\invocationCounter.cpp", the "InterpreterBackwardBranchLimit" is calculated by the following rules:
if (ProfileInterpreter) {
InterpreterBackwardBranchLimit = (CompileThreshold \* (OnStackReplacePercentage - InterpreterProfilePercentage)) / 100;
} else {
InterpreterBackwardBranchLimit = ((CompileThreshold \* OnStackReplacePercentage) / 100) << number\_of\_noncount\_bits;
}
InterpreterBackwardBranchLimit = (CompileThreshold \* (OnStackReplacePercentage - InterpreterProfilePercentage)) / 100;
} else {
InterpreterBackwardBranchLimit = ((CompileThreshold \* OnStackReplacePercentage) / 100) << number\_of\_noncount\_bits;
}
So if I run a piece of code on a server edition jvm, the InterpreterBackwardBranchLimit should be 10700 (CompileThreshold is 10000, OnStackReplacePercentage is 140, and InterpreterProfilePercentage is 33). But when I added -XX:+PrintCompilation, a loop with 10700 times would not print anything. When the loop growed up to 14564 times, the compiler began to work.
Could anybody give me some advice?
I use jdk1.7.0\_67, and the test code as following:
public class OSRDemo {
public static void main(String\[\] args) {
int result = 1;
for (int i = 1; i < 10700; i++) {//14564
result+=i;
}
System.out.println(result);
}
}
public static void main(String\[\] args) {
int result = 1;
for (int i = 1; i < 10700; i++) {//14564
result+=i;
}
System.out.println(result);
}
}
Thank you very much!
Thomas