The SBP (System Balancing Parameters) command displays and sets the time interval used for computing system utilization information.

Syntax

        ┌◄─────────────────────────────────────────────┐  
── SBP ─┴─┬─────────────────────────────────────────┬──┴────┤
          ├─ /1\ ── CPURATE ────┬─────┬── <number> ─┤
          │                     └─ = ─┘             │
          ├─ /1\ ── INTERVAL ───┬─────┬── <number> ─┤
          │                     └─ = ─┘             │
          └─ /1\ ── SLICERATE ──┬─────┬── <number> ─┘
                                └─ = ─┘

Explanation

SBP

Displays the current settings.

SBP CPURATE = <number>

Sets the time interval (in seconds) for computing CPU processor rate information for processes. The number must be in the range 10 to 60. The default is 20.

The CPURATE can be displayed by the A (Active Mix Entries) and the ADM (Automatic Display Mode) commands. For example if the SBP CPURATE is set to 15 seconds, the operating system computes processor rates every 15 seconds. The displayed processor rate is then the processor time used over the last 15 seconds shown as a percentage of 15 seconds; a task that used 3 seconds of processor time in the last 15 seconds would have a CPURATE of 20 percent.

SBP INTERVAL = <number>

Sets the time interval (in seconds) for computing system utilization information. The information can be displayed by the U (Utilization) command. The default interval is 10 seconds.

SBP SLICERATE = <number>

Sets the rate, in slices per second, at which processes of the same priority are sliced. The slice rate value is a number between 10 and 200 that indicates the number of slices (process stack switches) per second that the system is to make for processes that have the same priority level. All processes at the same priority level are treated in a round-robin manner. Processes at a higher priority always immediately preempt processes at a lower priority regardless of the setting of SLICERATE. The default is 50.

Example

SBP

---- SYSTEM BALANCING PARAMETERS ----
   INTERVAL = 10 SECONDS
   SLICERATE = 60 SLICES PER SECONONDS
   CPURATE = 10 SECONDS
   PROCSCHEDULING = BYGLOBAL
   SCHEDULING QUEUES = 1

Considerations for Use

Setting the Slice Rate Value

A short SBP INTERVAL value provides an immediate picture of system utilization, and a long interval gives a better average picture. With a short interval, sudden changes are accurately reflected. With a longer interval, changes are "smoothed out." The default interval is 10 seconds, which can be termed short. An interval shorter than 10 seconds is not advisable because the statistics tend to fluctuate too much.

You can use the U (Utilization) command to obtain current system utilization statistics.

For the systems that support SLICERATE adjustment, the lower the slice rate—that is, the fewer the number of process switches per second for a given priority—the better a compute-bound task can run. Up to a point, the higher the SLICERATE, the better I/O-bound tasks can run. For a general mix, the slice rate should be in the range of 30 to 90 slices per second. The most efficient tuning usually comes from using a moderate SLICERATE and tiered job priorities, where compute-bound jobs are relegated to relatively lower priorities, while I/O-bound jobs are given relatively higher priorities. If you set the slice rate too low, you risk poor I/O service. If you set the slice rate too high, you risk poor processor utilization, because the processor must switch between stacks at a much higher rate, thereby making poorer use of processor memory caching.