WebSphere Application Server - Express, Version 6.0.x     Operating Systems: AIX, HP-UX, Linux, Solaris, Windows

Using the Runtime Performance Advisor

Why and when to perform this task

The Runtime Performance Advisor provides advice to help tune systems for optimal performance and is configured using the WebSphere Application Server administrative console or the wsadmin tool . The Runtime Performance Advisor uses Performance Monitoring Infrastructure (PMI) data to provide recommendations for performance tuning. Running in the Java Virtual Machine (JVM) of the application server, this advisor periodically checks for inefficient settings, and issues recommendations as standard product warning messages. View these recommendations by clicking Troubleshooting > Runtime Messages > Warning in the administrative console. Enabling the Runtime Performance Advisor has minimal system performance impact.

Steps for this task

  1. Enable PMI in the application server administrative console as described in the Enabling PMI using the administrative console article. To obtain advice, you must first enable PMI through the administrative console and restart the server. The Runtime Performance Advisor enables the appropriate monitoring counter levels for all enabled advice when PMI is enabled. If specific counters exist that are not wanted, disable the corresponding advice in the Runtime Performance Advisor panel, and disable unwanted counters. If specific counters exist that are not wanted, or when disabling the Runtime Performance Advisor, you might want to disable PMI or the counters that the Runtime Performance Advisor enabled.
  2. Click Servers > Application servers in the console navigation tree.
  3. Click server_name > Runtime Performance Advisor Configuration.
  4. Under the Configuration tab, specify the number of processors on the server. This setting is critical to ensure accurate advice for the specific configuration of the system.
  5. Select the Calculation Interval. PMI data is taken over an interval of time and averaged to provide advice. The calculation interval specifies the length of the time over which data is taken for this advice. Therefore, details within the advice messages display as averages over this interval.
  6. Select the Maximum Warning Sequence. The maximum warning sequence refers to the number of consecutive warnings that are issued before the threshold is updated. For example, if the maximum warning sequence is set to 3, then the advisor only sends three warnings to indicate that the prepared statement cache is overflowing. After three warnings, a new alert is only issued if the rate of discards exceeds the new threshold setting.
  7. Click Apply.
  8. Click Save.
  9. Click the Runtime tab.
  10. Click Restart. Select Restart on the Runtime tab to re-initialize the Runtime Performance Advisor using the last configuration information that is saved to disk.
    Note: This action also resets the state of the Runtime Performance Advisor. For example, the current warning count is reset to zero (0) for each message.
  11. Simulate a production level load. If you use the Runtime Performance Advisor in a test environment, do any other tuning for performance, or simulate a realistic production load for your application. The application must run this load without errors. This simulation includes numbers of concurrent users typical of peak periods, and drives system resources, for example, CPU and memory, to the levels that are expected in production. The Runtime Performance Advisor only provides advice when CPU utilization exceeds a sufficiently high level. For a list of IBM business partners providing tools to drive this type of load, see the article, Performance: Resources for learning in the subsection of Monitoring performance with third party tools.
  12. Select the check box to enable the Runtime Performance Advisor.
    Note: To achieve the best results for performance tuning, enable the Runtime Performance Advisor when a stable production level load is being applied.
  13. Click OK.
  14. Select Warnings in the administrative console under the WebSphere Runtime Messages in the WebSphere Status panel or look in the SystemOut.log file, which is located in the install_root/profiles/profile_name/logs/server_name directory to view tuning advice. Some messages are not issued immediately.
  15. Update the product configuration for improved performance, based on advice. Although the performance advisors attempt to distinguish between loaded and idle conditions, misleading advice might be issued if the advisor is enabled while the system is ramping up or down. This result is especially likely when running short tests. Although the advice helps in most configurations, there might be situations where the advice hinders performance. Because of these conditions, advice is not guaranteed. Therefore, test the environment with the updated configuration to ensure that it functions and performs better than the pervious configuration.

    Over time, the advisor might issue differing advice. The differing advice is due to load fluctuations and the run-time state. When differing advice is received, you need to look at all advice and the time period over which it ia issued. Advice is taken during the time that most closely represents the peak production load.

    Performance tuning is an iterative process. After applying advice, simulate a production load, update the configuration that is based on the advice, and retest for improved performance. This procedure is continued until optimal performance is achieved.

What to do next

You can enable and disable advice in the Advice Configuration panel. Some advice applies only to certain configurations, and can only be enabled for those configurations. For example, unbounded Object Request Broker (ORB) service thread pool advice is only relevant when the ORB service thread pool is unbounded, and can only be enabled when the ORB thread pool is unbounded. For more information on Advice configuration, see the article, Advice configuration settings.



Sub-topics
Runtime Performance Advisor configuration settings
Advice configuration settings
Viewing the Runtime Performance Advisor recommendations
[Version 6.0.2]Understanding the lightweight memory leak detection
[Version 6.0.2]Getting the automated heap dump generation support

Related tasks
Obtaining performance advice from the performance advisors

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Last updated: Jun 8, 2005 12:45:23 PM EDT
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