Performance focus definitions for ThruPut Manager AE

Relevant to you?

By default, SLM aims to balance batch demand with batch throughput. However, installations have different load profiles, demands, and goals that may require SLM to tailor its response to changing performance conditions.

You can select from a provided set of Performance Focus Definitions to customize the intent of SLM performance driven actions to match your installation's requirements and environment.

To meet your needs, you can update the provided definitions and create new ones. Using an operator command, SLM ACTIVATE FOCUS, the active Performance Focus Definition can be changed on the fly to handle changing requirements during the processing day.

You can also select to automatically activate a specific Policy Service Mode when the Performance Focus Definition is changed.  This enables you to change batch workload constraints such as maximum executing jobs at the same time.  By specifying a mode other than STANDARD for the default Performance Focus Definition, you are able to have a default mode for a policy that is one other than STANDARD.

How does it work?

When you create a new policy, SLM automatically defines the following three Performance Focus Definitions:

1. CONTROL: This focus definition is designed to tightly control batch initiation and is very sensitive to the values for the Performance Index and delays in each batch service class.
2. THRUPUT: This focus definition emphasizes batch throughput and, while it still guards against over initiation, it is more tolerant of higher values in each batch service class for the Performance Index and particularly delays.
3. BALANCED: This focus definition strikes a balance between the other two and is the default active Performance Focus Definition for newly created policies.

If you update or if SLM loads a policy last updated prior to the support for Performance Focus Definitions, the policy will automatically be updated to include BALANCED, CONTROL, and THRUPUT, as well as a fourth additional definition, STANDARD. STANDARD is created with options that match those you were using prior to the addition of support for Performance Focus Definitions. In this case, STANDARD becomes the default active Performance Focus Definition so that you start with the same SLM performance-based algorithm behavior that existed before the upgrade.

When making changes to a Performance Focus Definition, it is recommended that initially it not be made the default active focus. Use the SLM ACTIVATE FOCUS operator command to temporarily make the new or updated definition active in order to determine whether the changes meet your goals.

When an SLM policy is loaded, the Performance Focus Definition designated as default active becomes the active Performance Focus Definition in the JESplex. The only exception to this rule is when the SLM policy is reloaded as a result of a WLM policy change. In that case, the active Performance Focus Definition remains as is, preserving any change made by the SLM ACTIVATE FOCUS operator command.

If you have enabled the option in the policy to automatically change the Policy Service Mode, when the default Performance Focus Definition is activated as a result of a policy load, the Policy Service Mode specified in the Performance Focus Definition is also activated at the same time.

A Performance Focus Definition must be given a unique 8-character name used to identify it and allow it to be activated by operator command. You can rename any Focus Definition, including the ones provided automatically by SLM. There must always be an active Performance Focus Definition which means there must always be at least one defined.

The following options make up a Performance Focus Definition:

• Use performance criteria only for initiator and job select decisions.
• Use OPP if enabled.
• Use WLM unknown delays when calculating total service class delay.
• Sensitivity to delays & PI.
• Initiator change responsiveness.
• System/Service Class Color Changes.
• Policy Service Mode

Use performance criteria only for initiator and job select decisions

SLM is to consider performance related criteria only when adjusting the number of initiators and job selection. The urgency of the work in the queue will not affect the decisions, although it will still determine the order of the queue and therefore the order in which it is selected.

This option is recommended to be enabled as it can further control overloading when there are long queues of batch jobs waiting for execution.

By default this option is enabled.

Use OPP if enabled

Disabling this option will disable any configured Online Performance Protection actions in the policy. This may be useful in times when online transaction volumes are low such as overnight batch processing.

By default this option is enabled.

Use WLM unknown delays when calculating total service class delay

When monitoring the performance of load in each service class, WLM attempts to identify and accumulate statistics on the reasons for delays that are blocking the load from running. Those that WLM cannot identify are classified as "unknown delays". In general, these are relatively minor, and can be mostly ignored. Unknown delays are not used in WLM service class velocity calculations.

By default, SLM factors these unknown delays into its total delay calculations gradually as the unknown delays become more significant. SLM uses the total delay percentages in its job selection and initiator deployment algorithms.

In some environments, it may be desirable to be even more sensitive to these delays.

If you are using a Performance Focus Definition with "Sensitivity to Delays & PI" set to 'Low", are experiencing higher levels of initiation than you would like, and monitoring shows significant unknown delays (at minimum more than 20%), create a new Performance Definition with this option enabled, activate it and monitor the resulting behavior.

Note that the SLM DISPLAY SERVICECLASS command displays the unknown delay percentage for each SLM service class.

By default this option is disabled.

Sensitivity to delays & PI

This option enables you to determine how sensitive SLM initiator deployment and job selection algorithms are to the Performance Index values and delay percentages. For example, changing to "Low" sensitivity makes SLM more tolerant of increases in these values. This option should be changed if your installation has requirements for PIs and/or delays for your SLM managed batch workload that differ from those that you are currently experiencing under SLM.

By default this option is set to "High".

Initiator change responsiveness

This option determines how quickly the SLM initiator deployment algorithm reacts as performance conditions change. Consider changing this option if you have batch load that spikes frequently, with periods of heavy usage alternating with periods of low usage.

By default this option is set to "Low".

System/Service Class Color Changes

After evaluating performance conditions, SLM assigns a "color" to the system and to each of the batch Service Classes. These are used in the initiator deployment and job selection algorithms. Normally SLM smooths out these changes to avoid dramatic swings. You can specify "Accelerated" to eliminate this smoothing when performance conditions improve. Consider changing this option if you have batch load that spikes frequently, with periods of heavy usage alternating with periods of low usage.

By default this option is set to "Smooth".

Policy Mode

Specify the Policy Service Mode to be activated simultaneously with this Performance Focus Definition.  

The Service Mode must be enabled for at least one Control Center or Work Type. If the Service Mode is not enabled, the policy will not pass the validation.

For the Service Mode to take effect, the option to switch Service Mode when activating a definition must be enabled.  Note that there is a reminder on the screen that shows whether the option is enabled or disabled in the policy being edited.

Setup Considerations

In the SLM Policy you edit, rename or delete existing Performance Focus Definitions, create new ones and designate one definition as the default active Performance Focus Definition.

Specify if you want to automatically change the Policy Service Mode when a Performance Focus Definition is activated.

Use a line command appropriate to the operation you want to perform on the line for that particular definition. To create a new definition, type "E" next to an empty name slot. You can define up to eight Performance Focus Definitions.

The following panel is displayed to edit an existing definition or add a new one.