This tip provides guidelines for monitoring high priority job CPU utilization. Using a guideline value from this tip, you can be prepared and receive alerts to:
- Possible response time degradation in the near future
- Possible cause for longer than normal response time
Managing performance is important to ensure your IBM eServer iSeries server maintains availability. Don't wait until your iSeries server slows down before you deal with performance issues. By monitoring CPU utilization for critical applications, you can receive warnings before major problems occur. This tip provides updated cumulative CPU utilization guideline values for monitoring your interactive-like, response-time critical applications. Use a guideline value to alert you to possible response time degradation in the "near future" or a possible cause for "longer than normal" response times. The guideline values increase as the number of processors available in the system or partition (LPAR configuration) increases.
Guidelines are just that -- guidelines. There may be instances when response time is acceptable at values that are higher than the guideline values shown. Alternatively, there may be instances when response time is not acceptable and the CPU utilization guidelines are not exceeded.
The following table shows the updated set of guideline values for monitoring steady-state CPU utilization of high priority jobs that run under OS/400, where response time is an important consideration. These guidelines apply to jobs or threads that perform work based upon input data and receiving a response. This work includes jobs that do 5250 transactions, Web serving, Domino server functions, and SQL-oriented database file operations.
Number of processors per system/partition
|Guideline values for high priority jobs or threads|
For your application environment, you need to determine the OS/400 run priority values for jobs or threads that you want to monitor. The guideline for a job or thread at any given priority value includes the cumulative utilization of all jobs or threads that are active at equal or higher priority, compared to the priority of selected jobs or threads. You then monitor the cumulative CPU utilization of all jobs or threads running at equal or higher priority to that value. For example, we assume you want to monitor HTTP serving functions. Find out the run priority for the associated HTTP jobs or threads running under OS/400. By using HTTP configuration defaults, this would be OS/400 job or thread RUNPTY 25. By using a RUNPTY value of 25, you include the other OS/400 functions that run jobs and threads at RUNPTY values 0 (iSeries microcode) through 25.
Under OS/400, key high priority functions and applications with default RUNPTY values less than 25 include:
- 5250 jobs: These jobs have default priority value of 20.
- QSQSRVR jobs: Perform Call Level Interface DB2 UDB SQL functions used by IBM functions such as Management Central and typically by Java-based applications performing SQL. These jobs or threads default to running at priority value 10.
- QZDASOINIT jobs: Perform ODBC/JDBC SQL functions requested by client workstations. These jobs or threads default to running at priority 20.
- Domino for iSeries server jobs: Perform various Domino functions. These jobs default to running at priority 20.
- QRWTSRVR DDM target jobs: Perform DDM requests from a DDM source application. These jobs default to running at priority 20.
You can achieve an approximation of the cumulative CPU utilization according to job type run priority values from the Resource Utilization Expansion section of the System Report. This report is one of the functions available with the Manager feature of Performance Tools for iSeries (licensed program 5722-PT1). Performance data used by this report is collected using OS/400 Collection Services.
Starting with V5R1, iSeries Navigator (Operations Navigator) Management Central System Monitor or Job Monitor functions can assist you in real-time monitoring of CPU utilization values for the various jobs or servers that you want to monitor. Note that there is no specific real-time high priority work monitor function through V5R2. Here are some suggested techniques, all or some of which may be useful in your environment:
- Use Management Central System Monitor metric CPU Utilization (Interactive Jobs). This monitors average CPU utilization for all active jobs performing 5250 input and output (I/O) operations. The percent is relative to the total processor capacity (processor CPW) of the system or partition. This does not include work performed by a high priority job that is not performing 5250 I/O operations. For example, CPU utilization (Interactive Jobs) would not include CPU consumed by the QSQSRVR, QZDASOINIT, Domino, or HTTP-related jobs.
- Use Management Central Job Monitor and select job types Interactive, Batch Immediate, and Prestarted. Depending on your runtime environment, this may cover only the jobs in which you are interested. For example QSQSRVR, QZDASOINIT, and QRWTSRVR are prestarted jobs. The jobs that do most of the Domino server and HTTP server work run as Batch Immediate (BCI) jobs.
Note: CPU may be consumed by other batch immediate and prestarted jobs in your environment.
The following examples are windows from an active Job Monitor. They show the Batch Immediate, Prestarted, and Interactive jobs that would be included in a Job Monitor.
You cannot apply these high priority CPU utilization guideline values directly to another OS/400 performance metric - Interactive Feature utilization. A complete discussion about a set of guideline values for the Interactive Feature utilization is beyond the scope of this tip.
However, here is some information that may assist you with setting up your own guideline values for the Interactive Feature utilization:
- Each system or partition with a low interactive CPW capacity and a single 5250 job consuming high CPU utilization over an extended period is considered an administrative job and may use more CPU than you expect with a low interactive CPW capacity.
- Interactive Feature utilization applies where there are two or more 5250 jobs consuming high CPU utilization over an extended period of time. Interactive Feature utilization varies. It is based on the time interval of consistently high CPU utilization by jobs or threads that perform 5250 I/O operations and higher interactive CPW capacity for the partition or system.
- In general, the Interactive Feature utilization is computed by the microcode and the algorithm can be characterized as slow to anger (high 5250 jobs CPU utilization over several minutes time span) and quick to forgive (lowered 5250 job or thread CPU utilization over a "short" time span).
- At this time, the general recommended guideline value for Interactive Feature utilization is 70%. As with the high priority CPU utilization guideline, there may be times of acceptable response time when Interactive Feature utilization approaches 100%. There may also be times of degraded response time when less than 70% of the Interactive Feature is used over an extended period of time.
- As the percent of Interactive CPW rating approaches 50% or more of the partition's (or total system) Processor CPW rating, guideline values higher than 70% may be applied. Additional information requires further investigation.
This tip assumes you are using V5R1 or later. If you are running V4R5, you can use Management Central System monitor support, but not Job Monitor support (new in V5R1). V4R5 or later Management Central System monitor support includes monitoring Interactive Feature utilization. V4R5 or later OS/400 Collection Services collects Interactive Feature utilization. After associated performance database files (QAPMcccc) are generated, the Manager feature of Performance Tools for iSeries can produce System and Component reports that contain Interactive Feature utilization values.
For additional information, see:
- RedDraft Managing OS/400 with Operations Navigator V5R1 Volume 1: Overview and More, SG24-6226, provides overview information on Collection Services and detailed information on using a System or Job Monitor. You can find this RedDraft on the Web at (search on the RedDraft number SG24-6226):
- iSeries Information Center at: http://www.ibm.com/eserver/iseries/infocenter
Select Systems Management -> Performance.
This material has not been submitted to any formal IBM test and is published AS IS. It has not been the subject of rigorous review. IBM assumes no responsibility for its accuracy or completeness. The use of this information or the implementation of any of these techniques is a client responsibility and depends upon the client's ability to evaluate and integrate them into the client's operational environment.