2.5.2 CPU performance
CPU performance is defined as the efficient utilization of processor resources. Much of the improvement in optimizing processor utilization for Java has resulted from the creation of runtime compile systems. The inclusion of just-in-time (JIT) or "hotcode" compilers has significantly contributed to improving Java's runtime performance. IBM's JIT is included in all IBM JVMs, and is enabled by default. The JIT is tuned for long-running applications, but opportunities still exist for tuning the JIT for a particular application.
A distinguishing feature of the IBM JVM on AIX is built-in micropartitioning and dynamic logical partitioning (DLPAR) support. If the JVM will be running on an LPAR that is micropartitioned and resources will be shared with other partitions, take care to ensure that enough memory will always be available to the JVM.
In addition to these considerations, additional AIX operating system parameters are available to further optimize Java runtime performance. These tunable parameters are described in Chapter 4, AIX configuration.
Running WebSphere Application Server with the default Java runtime parameters will most likely not provide the best results. The defaults are configured to be satisfactory for all types of applications. But every application is unique, therefore, determining which tuning parameters will help a specific application is useful. The guidelines presented in Chapter 6, Tuning the IBM Java Virtual Machine, help you find the tuning parameters that take advantage of AIX capabilities and features and provide optimal results.
Note: IBM WebSphere Application Server 6 and WebSphere Application Server 6.1 use a Java 5 implementation of the Java runtime. Java 5 uses MXBeans for providing new dynamic monitoring functions as part of the javax.management package.
A description of one approach you can take to use this API for your runtime monitoring is provided in the developerWorks® article available at the following address: