IBM WebSphere Application Server Performance Cookbook

AIX Recipes

  1. CPU core(s) should not be consistently saturated.
  2. Unless energy saving features are required, ensure Power Management is set to Maximum Performance mode.
  3. Generally, physical memory should never be saturated with computational memory and the operating system should not page computational memory out to disk.
  4. If you're not tight on RAM, tune Virtual Ethernet Adapter minimum and maximum buffers on all AIX LPARs (including VIO) to maximum possible values to avoid TCP retransmits.
  5. Test disabling TCP delayed ACKs
  6. Monitor for TCP retransmissions and test tuning TCP/IP network buffer sizes.
  7. Use netstat -v to ensure that network switches are not sending PAUSE frames.
  8. In some situations, enabling network dog threads on multi-processor nodes may avoid a network processing bottleneck with the default single-CPU interrupt processing model.
  9. Operating system level statistics and optionally process level statistics should be periodically monitored and saved for historical analysis.
  10. Review operating system logs for any errors, warnings, or high volumes of messages.
  11. Review snapshots of process activity, and for the largest users of resources, review per thread activity.
  12. If the operating system is running in a virtualized guest, review the configuration and whether or not resource allotments are changing dynamically.
  13. If there are firewall idle timeouts between two hosts on a LAN utilizing a connection pool (e.g. between WAS and a database), consider tuning TCP keep-alive parameters.
  14. Bind your processes properly based on system topology.
  15. Use MCM memory affinity where appropriate.
  16. Find the optimal SMT configuration for the machine.
  17. Find the optimal hardware prefetching setting for your workload.
  18. Apply recommended tuning for Java applications.
  19. For large multi-threaded apps, use profiling to make sure that work is allocated equally amongst threads.
  20. For apps that use a lot of network I/O, tune networking parameters.
  21. For apps that make heavy use of native memory, experiment with and use the optimal malloc algorithm.
  22. Use profiling to evaluate the effects of tuning other parameters.

For details, see the AIX chapter.