Using Strobe for IMS

You can find detailed instructions for submitting measurement requests in the Strobe/ISPF Online Tutorials and the User-Guide. For a description of managing measurement sessions, refer to the Interpretation-and-Analysis-User-Guide.

This chapter discusses the considerations to keep in mind when submitting measurement requests and managing measurement sessions in an IMS environment, and describes how to create a Strobe Performance Profile.

Measuring an IMS Region

The structure of your Strobe measurement request depends on both the type of application and the information you are interested in obtaining. The following subsections offer some guidelines.

Deciding What to Measure

In an IMS subsystem, the IMS control region performs all terminal control functions and schedules incoming transactions for processing in one or more dependent regions. To study the resource demands associated with a particular IMS transaction or application, you need to measure the dependent region that services the transaction or application itself.

Both the DLISAS and IMS control regions can own the database datasets. To obtain a complete picture of your DASD performance for a dependent region, start concurrent measurement sessions in both the IMS control and DLISAS regions.

For DLB (IMS batch DL/I) applications, physical I/O occurs in the same address space in which the application modules execute. To see CPU, I/O activity, and attribution of DL/I service routines, measure the application.

Deciding When to Measure

In the case of a DL/I application executing in an online environment (such as MPRs, IFPs, and CICS), regularly scheduled measurement sessions conducted during peak periods can indicate trends in resource demand. You can initiate sampling during periods of interest and stop sampling during periods you do not need to measure. By switching sample datasets, you can isolate measurement session data for different programs in different sample datasets.

You can also measure an IMS environment and obtain periodic performance reports without interrupting the measurement process. To do this, switch to a new sample dataset, releasing the previous sample dataset. You can then produce a Strobe Performance Profile from the released sample dataset while sampling continues in the new sample dataset.

To get a complete picture of a batch IMS application’s activity, measure it, or the BMP region, over the entire duration of the job step. To do so, submit a measurement request for each job step of interest prior to the execution of the batch job. To ensure efficient sampling, specify an estimate of the run time for each job step.

Measuring CICS/DBCTL Regions

Before you measure a CICS/DBCTL region, ensure that the DBCTL connection is already active. Otherwise, Strobe for CICS issues message STR4128I DBCTL CONNECTION NOT ACTIVE; DBCTL DATA COLLECTOR QUIESCED and does not collect DBCTL-specific data.

If you function ship (the process by which CICS accesses resources on another CICS system) DL/I requests to the CICS/DBCTL region through MRO/ISC, or if you route DL/I transactions to the region, measure the region that owns the DBCTL connection.

Strobe invokes DBCTL DL/I attribution automatically and will produce attribution reports even if you suppress the CICS Performance Supplement. If, however, you specify CICS=NOATTR when you submit the measurement request, Strobe will not collect attribution data for either CICS or DBCTL.

For more information on measuring CICS regions, see Measuring a CICS Region.

Measuring Multiple Address Spaces at the Same Time

If you have licensed the Strobe AutoStrobe option, you can create and save groups of Strobe measurement requests to be processed at a later time. These collections of measurement requests are called request groups. Each of the measurement requests in a request group is known as a request group element.

You can create associations between request group elements. This capability allows you to measure jobs that are executing in different, but related, address spaces at the same time. For example, you can measure an IMS application that processes data managed by Db2. You can then see a more complete picture of the application’s overall performance by reviewing the Performance Profiles for both the IMS and the Db2 regions. This capability can be particularly useful during the testing phase of application development.

For more information, refer to the User-Guide.

Collecting IMS Data

If your installation uses the standard IBM-supplied names (DFSMVRC0 for control and DL/I regions, DFSRRC00 for dependent regions and batch) for the load modules invoked from the EXEC statement that initializes an IMS job step, Strobe automatically invokes Strobe for IMS whenever you measure an IMS region.

If your installation does not use the standard names for these load modules, then the method you use to invoke Strobe for IMS depends on how your Strobe system programmer configured your Strobe system. You may need to specify the IMS operand on the Strobe command language ADD operation or enter a Y in the IMS field of the Strobe - Data Collectors panel. Check with your Strobe system programmer to determine whether you must specify this operand.

Collecting Transaction Count and Average Service Time Information

For message processing regions,Strobe identifies the number of times a transaction executed during the measurement session, as well as the average service time for each transaction. This information is collected by default, and is displayed on the Transaction Summary report in the Performance Profile.

Because Strobe automatically collects the transaction count and service time data, you do not need to specify any additional parameters when measuring message processing regions.

Suppressing Transaction Count and Service Time Information

If you do not wish to collect transaction count and service time information, complete the following steps:

1. Select Option 1 from the Strobe Options menu. Strobe displays the Strobe - Add Active Request panel.

2. Enter Y in the Data Collectors field and press Enter. Strobe displays the Strobe - Data Collectors panel (see the following figure).
   

   Strobe

    - Data Collectors Panel
   

3. Type Y in the IMS Data C field and press Enter to display the Strobe - IMS Data Collector Capture Option panel (see the following figure).
   

   Strobe

    - IMS Data Collector Capture Option Panel
   
   

4. Enter N in the Please specify IMS CAPTURE Option field on the Strobe - IMS Data Collector Capture Option panel.
5. Press Enter to submit the measurement request.

If you are using the Strobe command language, specify IMS=NOCAPTURE when you submit the ADD operation if you do not wish to collect additional transaction information.

Disabling Strobe for IMS

To specify that Strobe not invoke Strobe for IMS, complete the following steps:

1. Select Option 1 or Option 2 from the Strobe Options menu. Strobe displays the Strobe - Add Active Request panel or the Strobe - Add Queued Request panel.
2. Enter Y in the Data Collectors field of the Strobe - Add Active Request or the Strobe - Add Queued Request panel.
3. Enter N in the IMS field of the subsidiary Strobe - Data Collectors panel (Strobe - Data Collectors Panel).
4. Press Enter to submit the measurement request.

If you are using the Strobe command language, specify the NOIMS operand when you submit an ADD operation to disable Strobe for IMS.

Specifying NOIMS disables all IMS data collection, including DL/I attribution.

Disabling Strobe IMS Attribution

By default, Strobe gathers attribution data to produce the Attribution of CPU Execution Time and Wait Time reports. To suppress collection of attribution data for these reports without disabling all IMS data collection, complete the following steps:

1. Select Option 1 or Option 2 from the Strobe Options menu. Strobe displays the Strobe - Add Active Request panel or the Strobe - Add Queued Request panel.
2. Enter Y in the Other Parameters field and press Enter. Strobe displays the Strobe - Other Parameters panel.
3. In the Other Parameters field, specify IMS=NOATTR.

4. Press Enter to submit the measurement request.

   Strobe

    - Other Parameters Panel (Suppressing Attribution)
   

If you are using the Strobe command language, specify the IMS=NOATTR operand when you submit an ADD operation to suppress the collection of attribution data.

To create a Strobe Performance Profile:

• WithStrobe/ISPF, select Option 4 from the Strobe Options menu
• In batch, execute the STROE procedure.

You can find detailed information about creating a Strobe Performance Profile in the Strobe/ISPF Online Tutorials and the User-Guide.

Once you have created the Strobe Performance Profile, analyze the reports to identify performance improvement opportunities. The remaining chapters of this book present a sample analysis of Strobe Performance Profiles for IMS dependent regions, CICS/DBCTL regions, and IMS supervisory regions.

There may be times when you would like to suppress some of the IMS-specific reports in the Strobe Performance Profile. The following subsections describe which reports can be suppressed, and how to suppress them.

Suppressing DL/I CPU and Wait Reports

You can suppress the DL/I CPU and Wait reports in the Strobe Performance Profile by specifying the NODLI option.

1. Enter Y in the DETAIL REPORTS field of the primary Strobe - Produce a Performance Profile panel (see the following figure).

   Strobe - Produce a Performance Profile Panel

   

2. On the subsidiary Strobe - Detail For a Performance Profile panel, specify NODLI in the OTHER PARAMETERS field (see the following figure).
   Strobe - Detail For a Performance Profile Panel

   
   

If you are using the STROE or STROXE procedure, specify the NODLI option on the RPTPARM parameter to suppress the DL/I CPU and Wait reports.

Suppressing Attribution Reports in the Strobe Performance Profile

To limit or suppress the Attribution of CPU Execution Time and Wait Time reports in the Strobe Performance Profile, specify any of the parameters described in the following sections.

Suppressing Attribution Reports with Low Activity

You can suppress attribution reports for any system service module in which the total CPU or wait time percentage is less than a specified baseline. To do this, specify the ATTR=nn.n parameter, where nn.n is the baseline percentage.

1. Enter Y in the TAILOR REPORTS field of the primary Strobe - Produce a Performance Profile panel.
2. On the subsidiary Strobe - Tailor Reports panel, specify a baseline percentage between 00.1 and 99.9 in the Compress below % portion of the ATTRIBUTION Reports field (see the following figure).

When you submit a batch job using the STROE or STROXE procedure, specify ATTR=nn.n.

Strobe - Tailor Reports Panel (Attribution Reports with Low Activity)

Suppressing All Attribution Reports

To suppress all Attribution reports:

1. Enter Y in the TAILOR REPORTS field of the primary Strobe - Produce a Performance Profile panel.
2. On the subsidiary Strobe - Tailor Reports panel, enter Y in the SUPPRESS portion of the ATTRIBUTION Reports field.

With the STROE or STROXE procedure, specify the NOATTR operand.

Suppressing IMS-Specific Attribution Reports

To suppress the Attribution of CPU Execution and Wait Time reports for IMS service modules only:

1. Enter Y in the TAILOR REPORTS field of the primary Strobe - Produce a Performance Profile panel.

2. On the subsidiary Strobe - Tailor Reports panel, enter Y in the Suppress reports for DL/I field (see the following figure).

   Strobe - Tailor Reports Panel (Suppressing IMS Attribution Reports)

   
   

With the STROE or STROXE procedure, specify the NOATTR=IMS operand.