IBM Power7 Optimization And Tuning Manual page 197

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.jitMonitorEntry
Garbage Collection impact: The impact of initializing new objects and of GC is shown in
Example B-13 on page 180 as the 12.13% of ticks in the libj9gc24.so shared object. This
high GC impact is related to the excessive creation of Double objects in the sample
program.
Java method execution: In Example B-14, the profile shows the time that is spent in the
ProfileTest class, which is broken down by method. Some methods appear more than
one time in the breakdown because they are compiled multiple times at increasing
optimization levels by the JIT compiler. Most of the ticks appear in the final highly
optimized version of the doWork()D method, into which the initialize()V and
calculate()V methods are inlined by the JIT compiler.
Example B-14 AIX profile excerpt showing Java classes and methods
Total Ticks For All Processes (JAVA) = 1450
Class
=====
ProfileTest
java/util/Random
java/lang/Float
java/lang/Double
java/lang/Math
Profile: ProfileTest
Total Ticks For All Processes (ProfileTest) = 1401
Method
======
doWork()D
doWork()D
doWork()D
initialize()V
calculate()V
initialize()V
Appendix B. Performance tooling and empirical performance analysis
===== ====== ======
1121 26.66 nathelp.s
Ticks
===== ======
1401 33.32
Ticks % Source
===== ====== ======
1385 32.94 ProfileTest.java
6 0.14 ProfileTest.java
4 0.10 ProfileTest.java
3 0.07 ProfileTest.java
2 0.05 ProfileTest.java
1 0.02 ProfileTest.java
======= =====
549fc0
%
38 0.90
5 0.12
3 0.07
3 0.07
Address Bytes
======= =====
1107283bc
110725148
110726e3c
1107262dc
110724400
1107255c4
cc0
b54
464
156c
b4c
144
d04
181