CPU capping and normalizing

This section describes the facilities provided by BMC ThruPut Manager to limit the CPU amount that any particular job can request from the system. Services are also provided to "normalize" the CPU value across CPUs to reflect different processor speeds.

Description

MVS does not provide any means to limit the total CPU time that a job may request. The only service available is the ability to provide a default value per step when the user has not coded CPU step time in the JCL. This presents the installation with some problems:

1.  It only takes place when the user has not coded any CPU values. Hence, unless the installation adds code in a system exit to remove CPU values coded by the user, the CPU requirements for any given job are unpredictable. This is true regardless of the job class.
2.  More important, the default CPU values are per step. For example, if the default value is 10 seconds a three-step job could run for as long a 30 CPU seconds. A six-step job could consume up to 60 CPU seconds. For the purpose of initiator deployment to meet batch services, this is undesirable, since the execution time of any particular job cannot be predicted.
   BMC ThruPut Manager provides a solution to these problems with the "CPU Capping and Normalizing" facility.

CPU Capping

The Job Action Language allows you to specify a Job CPU limit for a particular job or type of job. This facility is similar to the value having been coded on the JOB statement.

Please note that the actual limit value is "inserted" in the job prior to the SMF exit for job initiation (IEFUJI).

The value is applied to a job using the JAL action statement SET with the keyword CPUCAP. For example:

The above statement will put a JOB CPU limit of 30 seconds on a particular job.

CPU Normalization

To complement the CPU Capping facility, BMC ThruPut Manager offers a CPU normalization service. This allows an installation to adjust CPU limits to reflect the differences in CPU speed by different processors in a MAS complex.

With the JAL SET statement, you can request that the CPU values for a particular job or type of job be "normalized". The normalization factors are CPU dependent and are provided to BMC ThruPut Manager in the JES2 TMPARM statement through the keyword FACTORn. Up to 8 sets of factors can be specified, and the appropriate set can be selected through the JAL statement SET NORMALIZE.

Before the SMF exit for job initiation (IEFUJI) and after the CPU limit is applied, the JOB CPU time and the STEP CPU times are then multiplied by the factors provided in the TMPARM statement described in Installation Guide

To request CPU normalization in JAL, you use the action statement SET and the keyword NORMALIZE. For example:

The above statement indicates to BMC ThruPut Manager that the particular job is to have the CPU values normalized prior to execution.

Assume you have specified more than one set of normalization factors on the TMPARM statement:

TMPARM ...
FACTOR1=(2.8 PRD1),(1 PRD2),(2.8 PRD3),(3 PRD4),
FACTOR2=(3.3 PRD1),(2 PRD2),(2.8 PRD3),(3.5 PRD4),
FACTOR3=(4 PRD1),(5.5 PRD2),(5.5 PRD3),(4 PRD4),
...

In JAL, you can then select the appropriate set by using the FACTOR keyword on the SET NORMALIZE statement:

For a further description of the SET statement, refer to the JAL-Reference-guide.

Implementation Summary

To implement CPU Capping, you do not have to make any special provisions. Simply code the appropriate JAL SET statement.

To implement CPU normalization, you must provide the factors to be used in the normalization process:

• The factors are provided with the JES2 TMPARM card described in Installation-guide.
• The JES2 TMPARM statement allows you to specify a factor to be associated with a particular processor by specifying the SMFID of that particular system. You can therefore have a single TMPARM control statement for all the systems associated with a given MAS complex.
• Up to 8 different sets of factors can be supplied through TMPARM and selected through JAL, allowing you to accommodate jobs from widely varying environments. Each set of factors can specify up to 32 systems.
• If normalization is requested but no factors are supplied, no adjustments are made to the CPU values.

TMSS Initialization Statements

There are no TMSS initialization statements associated with this function. Instead, the FACTORS are provided with the JES2 TMPARM statement. The reason for this is simple: it allows you to execute jobs and apply the FACTORS even if the TMSS address space is not active.

TMPARM - The FACTORn Keyword

The FACTORn keyword is part of the BMC ThruPut Manager JES2 initialization statement TMPARM. It has the form:

where:

Is a digit from the range 1-8, uniquely identifying a set of factors.  For the syntax and keyword placement, refer to Installation Guide.

Facilities Summary