IBM 360 User Manual

IBM Internal Use Only
Measuring Techniques
TERMINOLOGY
System functions, measured or derived, are referred to
throughout this manual, especially in the examples on
measurement techniques. Measured system functions are
measured directly by the counters in the Basic Counter
Unit. Derived system functions are derived from previously
measured system functions by using mathematical
formulas. Derived system functions can also be measured
directly by the counters in the Basic Counter Unit;
however, to achieve maximum efficiency of the Basic
Counter Unit, measuring system functions that can be
derived should be kept at a minimum.
Measured System Functions
Total Elapsed Time is measured by monitoring the time
that a system is not in the stopped state. The stopped state
is indicated by the manual light and caused by pressing
STOP or SYSTEM RESET on the system control panel.
Total elapsed time provides a base of reference against
which other comparisons can be computed.
Total Compute is the signal present when bit number 14 of
the program status word (PSW) is off, indicating that the
processor is executing instructions.
Processor N ot Active (Wait State) is the signal present when
bit number 14 of the PSW is on, indicating that the
processor is not executing instructions.
Channel Busy is a signal made available to the Basic
Counter Unit, once for the multiplexer channel, and once
for each selector channel on the system.
Any Channel Busy is created by using the combinatorial
logic on the Basic Counter Unit patch panel. It is the logical
OR of any channel busy.
Wait and Any Channel Busy is created by using the
combinatorial logic on the Basic Counter Unit patch
panel. It is the logical OR of any channel busy, and the
resultant output of the OR ANDed with processor not
active.
Channel Overlap is a measurement of the time the
input/output channels are operating simultaneously. The
logical AND of selector channel-one busy and selector-two
busy provides this measurement.
Derived System Functions
Total Wait is the total elapsed time minus total compute.
Wait Only (System Idle) is the total wait minus wait and
any channel busy.
Compute and Any Channel Overlap is any channel busy
minus wait and any channel busy.
Compute Only is the total compute minus compute and
any channel overlap.
EXAMPLES
The user must decide on and develop his own techniques
and define his own system functions, but certain examples
may prove helpful to him in formulating plans. Several
examples are presented in this section that illustrate basic
measurement techniques, The numbers shown in the
examples are for illustration only and are not to be
considered as standard cases.
Each example given consists of three parts:
Objectives
Patch Panel Wiring Diagram
Summary
Example 1
During the processing of a job or jobs on System/360, the
CPU either overlaps or non-overlaps the I/O channels.
Overlap and non-overlap are interrelated and influence the
efficiency of a system. Overlap exists when one or more I/O
channels perform I/O operations while the CPU simultane
ously executes instructions. Non-overlap exists when I/O
channels perform I/O operations at one time and the CPU
executes instructions at another time.
Objectives
Measure total elapsed time, any channel busy, compute and
any channel overlap and total compute. Derive compute
only, total wait, wait and any channel busy, and wait only.
Wiring
The wiring for this example is shown in Figure 31.
The stop state on a System/360 (indicated by a manual
light and caused by pressing STOP or SYSTEM RESET on
the system control panel) is being monitored. One stop
state signal is wired to the STOP hub, another stop state
signal is wired as input to a NOT function, the NOT
function output is then wired to the START hub and
causes total counter stoppage if either STOP or SYSTEM
RESET on the system control panel is pressed.
Any +1 hub is wired to a TMG hub and results in total
elapsed time.
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IBM 360 Specifications

General

Brand	IBM
Model	360
Category	Network Hardware
Language	English