IBM JVM Options
As with other JVMs, the settings used for IBM’s JVM on an AIX platform can impact on the performance and stability of the overall system.
For more information, see IBM’s JVM tuning guide: http://publib.boulder.ibm.com/infocenter/wasinfo/v6r0/index.jsp?topic=%2Fcom.ibm.websphere.express.doc%2Finfo%2Fexp%2Fae%2Ftprf_tunejvm.html
Consider the values of the following IBM JVM options:
- -Xcompressedrefs (64-bit only) The use of compressed references improves the performance of many applications because objects are smaller, resulting in less frequent garbage collection and improved memory cache utilization. Certain applications might not benefit from compressed references. Test the performance of your application with and without compressed references to determine if they are appropriate. For default option settings, see the JVM command-line options.
- -Xjit:codetotal=262144 Maximum size of memory (KB) allocated for compiled data. See:
IV26401: REDUCED PERFORMANCE AFTER HEAVY CLASS RE-LOADING
IZ73689: 64-BIT JAVA RUNS VERY SLOWLY WHEN JIT CODE CACHE IS FULL
- -Xcodecache32m This option sets the size of each block of memory that is allocated to store the native code of compiled Java methods. See:
- -Xgcpolicy:gencon The gencon policy uses a concurrent mark phase combined with generational garbage collection to help minimize the time that is spent in any garbage collection pause. This policy is particularly useful for applications with many short-lived objects, such as transactional applications
- -Xlp Requests the JVM to allocate the Java object heap with large pages.
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