Performance tuning for WebSphere Application Server Hypervisor Edition for IBM AIX

To optimize performance, operating system and WebSphere Application Server paramaters are automatically tuned in the IBM® WebSphere® Application Server Hypervisor Edition virtual image.

Operating System Tuning

The IBM AIX 6.1 operating system included on your virtual images has been tuned for increased performance. The following tuning parameters are automatically set in the image and can be modified using virtuser only:
  • Environment variables
    • The following environment variables are set for virtuser in ~virtuser/.profile:
      envfile=~virtuser/.profile
      echo "\nexport AIXTHREAD_SCOPE=S" >> $envfile
      echo "\nexport LDR_CNTRL=DATAPSIZE=64K@TEXTPSIZE=64K@STACKPSIZE=64K" >> $envfile 
  • User resource limits
    • The following user resource limits are set for virtuser in /etc/security/limits
      chuser nofiles=-1 data=-1 stack=-1 rss=-1 cpu=-1 virtuser
    • nofiles soft file descriptor limit recommended value: -1 (unlimited)
    • data soft data segment size in blocks recommended value: -1 (unlimited)
    • stack soft stack segment size in blocks recommended value: -1 (unlimited)
    • rss soft real memory usage in blocks recommended value: -1 (unlimited)
    • cpu soft per process CPU time limit in seconds recommended value: -1 (unlimited)
  • Network tuning parameters
    • The following network tuning parameters are set
      no -p -o tcp_timewait=1
      no -p -o tcp_keepidle=600
      no -p -o tcp_keepintvl=10
      no -p -o tcp_keepinit=40
      no -p -o sack=1
      no -p -o rfc1323=1
      no -p -o sb_max=1114112
      no -p -o tcp_mssdflt=1448

WebSphere Application Server Tuning

WebSphere Hypervisor Edition automatically tunes application servers and deployment managers based on the virtual resources allocated to the virtual image. The automatic tuning attempts to optimize your virtual system for performance, but can easily be changed to meet the specific needs of your application. The Java heap size is sized based on the allocated virtual memory, WebSphere Application Server web container threads are sized based on the number of virtual CPUs.

-X parameters for WebSphere Application Server on pSeries:
  • -Xcodecache20m
    • Default value is 8MB.
    • Sets the unit size of the memory blocks that are allocated to store the native code of compiled Java methods. You can choose an appropriate size for the application being run. By default, this parameter is selected internally, according to the CPU architecture and capability of your system.
  • -Xlp64k
    • Default value is 4KB.
    • Use this setting with the IBM virtual machine for Java to allocate the heap using a 64KB page size (medium pages). Using this virtual memory page size for the memory that an application requires can improve the performance and throughput of the application, because of hardware efficiencies that are associated with a larger page size. AIX has rich support around 64KB pages, and 64KB pages are intended to be general purpose. You can change this setting without changing the operating system configuration.
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Last updated: January 29, 2018 07:35 AM GMT-06:00
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