Workload Statistics 

Definition

System statistics are written to the R/3 kernel and can be displayed using the workload monitor (Transaction ST03N). They provide system administrators with varied and detailed information on CPU time, numbers of database changes, roll out times and so on.

For Release 4.6C, the workload monitor has been enhanced to include GUI times, frontend network times and RFC time.

Use

You can use these statistics to compare the response times of different application servers over a specific period of time, for example, or to compare the number of users who are working on various application servers.

Integration

You can display the workload statistics for all task types (such as dialog, background, RFC, ALE and update). Alternatively you can display the statistics for a specific task type.

The table below defines the most important workload statistics:

Average CPU time

Average CPU time used in the work process.

During a dialog step, the CPU of the application server is used for processing (loading, generating, database request processing, ABAP processing and so on).

The CPU time is determined by the operating system. At the end of a transaction step, the R/3 work process queries the CPU time from the operating system. The CPU time is therefore not an additive component of the response time, unlike the wait, roll-in, load and database time.

Average response time

The average response time of a dialog step is the average time measured from the time a dialog sends a request to the dispatcher work process through the processing of the dialog up to the time the dialog is completed and the data is passed to the presentation layer. The response time between the SAP GUI and the dispatcher is not included in this value.

The response time does NOT include the time taken to transfer data from the R/3 frontend to the application server. For networks with low performance, this can create a highly subjective response time. The transfer time is contained in the GUI network time.

Response time is usually split into wait time plus dispatch time. The SAP response time is composed of the following components:

Response time = wait time + dispatched time

Dispatched time

= Generation time during runtime

+ Load time for programs, screens and CUA interfaces

+ Roll times to roll-in work data

+ ABAP processing time

+ Database time

+ Enqueue time for logical SAP lock procedures

+ CPIC/RFC time

+ Roll wait time (apart from task types RFC/CPIC/ALE).

The CPU time is not an additive component of the response time, but the sum of the CPU time that is used by the individual components. The CPU time therefore provides additional, independent information on the response time.

Average wait time

The time an unprocessed dialog step waits in the dispatcher queue for a free work process.

Under normal conditions, the dispatcher work process should pass a dialog step to the application process immediately after receiving the request from the dialog step. Under these conditions, the average wait time would be a few milliseconds. A heavy load on the application server or on the entire system causes queues at the dispatcher queue.

Average load time

The time needed to load and generate objects such as ABAP source code and screen information from the database.

Database calls

The number of parsed requests sent to the database

Database requests

The number of logical ABAP requests for data in the database. These requests are passed through the R/3 database interface and parsed into individual database calls.

The proportion of database calls to database requests is important. If access to information in a table is buffered in the SAP buffers, database calls to the database server are not required. Therefore, the ratio of calls/requests gives an overall indication of the efficiency of table buffering. A good ratio would be 1:10.

GUI time

The GUI time is measured in the work process and is the response time between the dispatcher and the GUI.

Roll ins

Number of rolled-in user contexts.

Roll outs

Number of rolled-out user contexts.

Roll in time

Processing time for roll ins.

Roll out time

Processing time for roll outs.

Roll wait time

Queue time in the roll area. When synchronous RFCs are called, the work process executes a roll out and may have to wait for the end of the RFC in the roll area, even if the dialog step is not yet completed. In the roll area, RFC server programs can also wait for other RFCs sent to them

Average time per logical DB call

Average response time for all commands sent to the database system (in milliseconds). The time depends on the CPU capacity of the database server, network, buffering, and on the input/output capabilities of the database server. Access times for buffered tables are many magnitudes faster and are not considered in the measurement.