JVM Tutorials - Herong's Tutorial Examples - Version 4.23, by Dr. Herong Yang
"long" Shift and Assignment: 30 Nanoseconds per Step
This section provides a tutorial example on how to perform benchmark tests to find out how long a shift and assignment loop will take to run. The answer is 30 nanoseconds per step.
Now I can add a shift operation in the assignment statement to measure the shift operation performance. Here is the test method:
/** * BenchmarkTestLong.java * Copyright (c) 2010, HerongYang.com, All Rights Reserved. */ class BenchmarkTestLong { ... // Test method for a shift operation in a loop public static long shift(int steps, BenchmarkRunner runner) { long x = 0; long i = 0; long last = steps; runner.startTimer(); for (i=0; i<last; i++) { x = i<<1; } runner.stopTimer(); return x; } }
Here are test results:
C:\herong\jvm>java -Xint -Xms100m -Xmx100m BenchmarkRunner BanchmarkTestInt shift 10000 100 10 ... Runs: 100, Ave: 272, Min: 251, Max: 279 - Per step in nanoseconds C:\herong\jvm>java -Xint -Xms100m -Xmx100m BenchmarkRunner BanchmarkTestInt shift 10000 100 100 ... Runs: 100, Ave: 54, Min: 50, Max: 56 - Per step in nanoseconds C:\herong\jvm>java -Xint -Xms100m -Xmx100m BenchmarkRunner BanchmarkTestInt shift 10000 100 1000 ... Runs: 100, Ave: 32, Min: 32, Max: 33 - Per step in nanoseconds C:\herong\jvm>java -Xint -Xms100m -Xmx100m BenchmarkRunner BanchmarkTestInt shift 10000 100 10000 ... Runs: 100, Ave: 30, Min: 30, Max: 31 - Per step in nanoseconds C:\herong\jvm>java -Xint -Xms100m -Xmx100m BenchmarkRunner BanchmarkTestInt shift 10000 100 100000 ... Runs: 100, Ave: 30, Min: 29, Max: 31 - Per step in nanoseconds C:\herong\jvm>java -Xint -Xms100m -Xmx100m BenchmarkRunner BanchmarkTestInt shift 10000 100 1000000 ... Runs: 100, Ave: 30, Min: 28, Max: 31 - Per step in nanoseconds
Conclusions based on the test result:
Last update: 2010.
Table of Contents
Downloading and Installing JDK 1.8.0 on Windows
Downloading and Installing JDK 1.7.0 on Windows
java.lang.Runtime Class - The JVM Instance
java.lang.System Class - The Operating System
ClassLoader Class - Class Loaders
Class Class - Class Reflections
JRockit JVM 28.2.7 by Oracle Corporation
Memory Management and Garbage Collectors
JVM Stack, Frame and Stack Overflow
Thread Testing Program and Result
CPU Impact of Multi-Thread Applications
I/O Impact of Multi-Thread Applications
Micro Benchmark Runner and JVM Options
Micro Benchmark Tests on "int" Operations
►Micro Benchmark Tests on "long" Operations
"long" Empty Loop: 25 Nanoseconds per Step
"long" Assignment Only: 24 Nanoseconds per Step
►"long" Shift and Assignment: 30 Nanoseconds per Step
"long" Add and Assignment: 34 Nanoseconds per Step
"long" Multiply and Assignment: 38 Nanoseconds per Step
"long" Division and Assignment: 53 Nanoseconds per Step
Performance Comparisons between "int" and "long"
Micro Benchmark Tests in JIT Compilation Mode