[ Previous | Next | Contents | Glossary | Home | Search ]
AIX Versions 3.2 and 4 Performance Tuning Guide

Chapter 13. Handling a Possible AIX Performance Bug

If you believe that you have found a possible performance problem in AIX, there are tools and procedures for reporting the problem and supplying problem-analysis data. They are intended to ensure that you get a prompt and accurate response with a minimum of effort and time on your part.

The main sections in this topic are:

Measuring the Baseline

Performance problems are often reported right after some change to the system's hardware or software. Unless there is a pre-change baseline measurement with which to compare post-change performance, quantification of the problem is impossible. Still better would be collection of a full set of performance and configuration information using the PerfPMR package, as recommended in "Check Before You Change".

Having the Performance Diagnostic Tool (PDT) installed and operational also provides a baseline of overall system performance.

Reporting the Problem

You should report suspected AIX performance problems to the IBM Software Service organization. Use your normal software problem-reporting channel. If you are not familiar with the correct problem-reporting channel for your organization, check with your IBM representative.

When you report the problem, you should supply the following basic information:

If this is the first report of the problem, you will receive a PMR number for use in identifying any additional data you supply and for future reference.

You will probably be asked to provide data to help IBM analyze the problem. An IBM-provided tools package called PerfPMR can collect the necessary data. On AIX Version 3.2.5, PerfPMR is an informal tool available from your IBM representative. On AIX Version 4, PerfPMR is an optionally installable package on the AIX Base Operating System distribution medium.

Obtaining and Installing AIX Version 3.2.5 PerfPMR

Your IBM representative can obtain a copy of AIX Version 3.2.5 PerfPMR on suitable media. To install PerfPMR you:

Installing AIX Version 4 PerfPMR

If you are not sure whether or not PerfPMR is installed on the system, enter:

# lslpp -lI bos.perf.pmr

To install PerfPMR from a high-density tape, enter:

# installp -acd/dev/rmt0.1 bos.perf.pmr

If the Base Operating System is on low-density tape, use rmt0.5 as the device.

The installation process places the PerfPMR package in a directory called /usr/sbin/perf/pmr. The package takes approximately 200KB of disk space.

Problem-Analysis Data

All of the following items should be included when the supporting information for the PMR is first gathered:

Capturing the Data

To capture and package the data in usable form, perform the following steps on each of the systems involved with the problem. If possible, step 6 should be performed on all of the systems at (approximately) the same time.

  1. Login as, or su to, root .
  2. PerfPMR captures more information if the tprof, filemon, and netpmon performance tools are available. In AIX Version 4, these tools are packaged as part of the Performance Toolbox for AIX. To determine whether the performance tools have been installed on the system, check with:
    $ lslpp -lI perfagent.tools
    If this package has been installed, the tools are available.
  3. Make sure that your PATH variable includes the directory that contains the PerfPMR executables.

    In AIX Version 4, add /usr/sbin/perf/pmr to the PATH. For example:

    # echo $PATH
    # PATH=$PATH:/usr/sbin/perf/pmr:
    # export PATH
    In Version 3, add to the PATH the directory in which you installed PerfPMR (in place of /usr/sbin/perf/pmr) and the directory for the performance tools, /usr/lpp/bosperf.
  4. In Version 4, the output of perfpmr will be written to /var/perf/tmp. In Version 3, you should:
    1. cd to a suitable directory, such as /tmp, in a file system that has at least 5MB of free space.
    2. Create a subdirectory to hold the data and switch to it, with:
              # mkdir perfdata
              # cd perfdata
  5. Track system activity for 1 hour with:
    # perfpmr 3600
    (in Version 3, perfpmr is named perfpmr.sh.)
  6. Combine the files into one compressed tar file with:
    # cd ..
    # tar -cvf pmrnumber.tarbin perfdata
    # compress pmrnumber.tarbin
    Where pmrnumber is the number assigned to the PMR by Software Service.
  7. Put the file on a diskette (or other portable volume) with, for example:
    # tar -cvf /dev/fd0 pmrnumber.tarbin.Z
  8. Label the portable volume with:
  9. Within the United States, send the data to:
    IBM Corporation, Mail Drop 2900
    11400 Burnet Road
    Austin, TX 78758
    Attn: AIX Program Services: V4DEFECT (or V3DEFECT, as appropriate)

Outside the United States, send the data to your IBM Software Service organization.

[ Previous | Next | Contents | Glossary | Home | Search ]