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WebSphere Real Time V2 service refresh 3



WebSphere® Real Time V2 service refresh 3 is now available from developerWorks®.


Service refresh 3 is now available for the following WebSphere Real Time products:

  • WebSphere Real Time V2 for Linux® on 32-bit x86
  • WebSphere Real Time V2 for Linux on 64-bit x86
  • WebSphere Real Time V2 for Real Time Linux on 32-bit x86
  • WebSphere Real Time V2 for AIX® on 32-bit POWER®
  • WebSphere Real Time V2 for AIX on 64-bit POWER

Service refresh 3 contains the following enhancements:
  • Java™ thread names are visible in the operating system when using the ps command.
  • Regular Java threads can be scheduled using different Linux scheduling policies.
  • Improved 32-bit throughput performance.
  • Substantially improved 64-bit throughput performance.
  • Improved analysis capabilities using the Health Center.
  • Improved 32-bit and 64-bit real-time performance (determinism).

For service refresh downloads, see

For WebSphere Real Time documentation, see

Java thread names

From service refresh 3, Java thread names are visible in the operating system when using the ps command. Examining process information can help you diagnose problems with your Java applications. For further information, and examples of using the ps command, see the problem determination section in the relevant WebSphere Real Time guide.

Controlling Linux scheduling policies for regular Java threads

By default, regular Java threads are run using the default Linux scheduling policy SCHED_OTHER. This policy maps Java threads to the operating system priority 0. From service refresh 3 you can alter the priority of regular Java threads using alternative Linux scheduling policies:
  • You can use SCHED_RR or SCHED_FIFO on WebSphere Real Time for Real Time Linux V2.
  • You can use SCHED_RR on WebSphere Real Time for Linux V2.

Using these scheduling policies gives you finer control over your application,
which can improve the real-time performance of Java threads. For more information about
thread scheduling and dispatching see the relevant WebSphere Real Time guide.

Throughput performance

From service refresh 3, the 64-bit version of WebSphere Real Time uses a JVM that supports compressed references. When using compressed references, the JVM stores all references to objects, classes, threads, and monitors as 32-bit values. Using compressed references improves the performance of many applications because objects are smaller, resulting in less frequent garbage collection and improved memory cache utilization. For further information about compressed references, see the memory management section of the Java Diagnostics Guide V6.

Arraycopy performance can be extremely important for many applications. In service refresh 3, both 32-bit and 64-bit versions of WebSphere Real Time have improved arraycopy performance.

Analyzing real-time performance using the Health Center

The IBM® Monitoring and Diagnostic Tools for Java - Health Center V1.2 provides new capabilities for analyzing WebSphere Real Time application performance. Using the WebSphere Real Time perspective, you can trace specific events over time using predefined trace points. The information is presented in various ways to help you analyze and identify potential performance improvements to your application. The Health Center also produces a determinism score that gives an indication of application performance.

Predefined views are available to present data on class loading, garbage collection and JIT compilation. You can also customize views to produce a unique representation of your data.

For more information about the Health Center, see the following page on developerWorks:

Improved determinism

Service refresh 3 provides improvements in the real-time performance of the Just-In-Time compiler, and of the Garbage Collector.

Document information

More support for: WebSphere Real Time
Java SDK

Software version: 2.0

Operating system(s): Linux

Software edition: All Editions

Reference #: 1429782

Modified date: 28 May 2010

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