Reporting a performance problem
You should report operating system performance problems to IBM® support. 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.
The AIX® Performance PMR (perfpmr) data collection tools are the best way to collect performance data when an AIX performance problem is suspected. Access these tools via the web at ftp://ftp.software.ibm.com/aix/tools/perftools/perfpmr Follow the instructions in the README file in the directory that matches the AIX version you will be measuring to obtain, install, and collect data on your system. Instructions are also provided on how to send the data to IBM support for analysis once a PMR has been opened.
When someone reports a performance problem, it is not enough just to gather data and then analyze it. Without knowing the nature of the performance problem, you might waste a lot of time analyzing data which may have nothing to do with the problem being reported.
Before you involve support personnel to report a problem, prepare in advance the information that you will be asked to supply to facilitate the problem to be investigated. Your local support personnel will attempt to quickly solve your performance problem directly with you.
Three further ways you can help to get the problem resolved faster are:
- Provide a clear written statement of a simple specific instance of problem, but be sure to separate the symptoms and facts from the theories, ideas and your own conclusions. PMRs that report "the system is slow" require extensive investigation to determine what you mean by slow, how it is measured, and what is acceptable performance.
- Provide information about everything that has changed on the system in the weeks before the problem. Missing something that changed can block a possible investigation path and will only delay finding a resolution. If all the facts are available, the performance team can quickly eliminate the unrelated ones.
- Use the correct machine to supply information. In very large sites it is easy to accidentally collect the data on the wrong machine. This makes it very hard to investigate the problem.
When you report the problem, supply the following basic information:
- A problem description that can be used to search the problem-history database to see if a similar problem has already been reported.
- What aspect of your analysis led you to conclude that the problem is due to a defect in the operating system?
- What is the hardware and software configuration in which the problem is
occurring?
- Is the problem confined to a single system, or does it affect multiple systems?
- What are the models, memory sizes, as well as number and size of disks on the affected systems?
- What kinds of LAN and other communications media are connected to the systems?
- Does the overall configuration include those for other operating systems?
- What are the characteristics of the program or workload that is experiencing
the problem?
- Does an analysis with the time, iostat, and vmstat commands indicate that it is CPU-limited or I/O-limited?
- Are the workloads being run on the affected systems: workstation, server, multiuser, or a combination?
- What are the performance objectives that are not being met?
- Is the primary objective in terms of console or terminal response time, throughput, or real-time responsiveness?
- Were the objectives derived from measurements on another system? If so, what was its configuration?
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.
Include all of the following items when the supporting information and the perfpmr data for the PMR is first gathered:
- A means of reproducing the problem
- If possible, a program or shell script that demonstrates the problem should be included.
- At a minimum, a detailed description of the conditions under which the problem occurs is needed.
- The application experiencing the problem:
- If the application is, or depends on, any software product, the exact version and release of that product should be identified.
- If the source code of a user-written application cannot be released, the exact set of compiler parameters used to create the executable program should be documented.