IBM Internal Use Only
Each function should be pictured as a series of many
short events. For example, the compute time is a series of
short compute times, separated by short wait times. Each
compute time is then followed by a short channel time,
sometimes partially overlapped with the compute time.
Figure 32 gives the relationship between the total-compute
and total-channel times, which is a valid way of measuring
systems performance. The numeric values shown in this
example are for illustration only and are not to be
interpreted as standard cases.
Example 2
IBM System/360 has one or more selector channels and a
multiplexer channel. These channels can operate at differ
ent times or channel operations can overlap each other.
Channels overlapping each other can also overlap the
operation of the central processing unit.
Objectives
To measure total elapsed time, total compute, any channel
busy, selector channel 1 busy, selector channel 2 busy,
multiplexer channel busy, and selector channel 1 /selector
channel 2 overlap.
Wiring
The wiring for this example is shown in Figure 33.
Summary
The counter results are:
Counter 0:
Counter 1:
Counter 2:
Counter 3:
Counter 4:
Counter 5:
Counter 6:
25,368,941,208
14,297,542,167
7,254,382,997
2,101,837,595
981,021,355
9,962,951,012
505,942,833
Total elapsed time
Total compute
Selector channel 1 busy
Selector channel 2 busy
Multiplexer channel busy
Any channel busy
Selector channel 1/selector chan
nel 2 overlap
At the timing rate of 1 MHz (1 microsecond) provided by
the Basic Counter Unit, the readings can be converted to:
Counter 0:
Counter 1:
Counter 2:
Counter 3:
Counter 4:
Counter 5:
Counter 6:
25,369 seconds
14,298 seconds
7,254 seconds
2,102 seconds
981 seconds
9,963 seconds
506 seconds
Total elapsed time
Total compute
Selector channel 1 busy
Selector channel 2 busy
Multiplexer channel busy
Any channel busy
Selector channel 1/selector chan
nel 2 overlap
The measured functions can also be expressed in per-
centages:
Total elapsed time
25,369 seconds
100.0%
Total compute
14,298 seconds
56.3%
Selector channel 1 busy
7,254 seconds 28.5%
Selector channel 2 busy 2,102 seconds
7.9%
Multiplexer channel busy
981 seconds
3.8%
Total Elapsed Time
Total Compute
Any Channel Busy
Compute Only
Compute and Any
Channel Overlap
Wait
Wait and Any
Channel Busy
Wait Only
81.8
62.3
154
19.5
32.4
72.2
12.9
59.3
Figure 32. Summary Profile for Example 1
Any channel busy
Selector channel 1/selector
channel 2 overlap
9,963 seconds
506 seconds
39.2%
1.9%
Example 3
As many as 15 programs may reside in a system
simultaneously and share the same processor by using the
multiprogramming facilities of System/360 Operating
System on an IBM System/360 Model 65. Actually, each
program resides in a separately protected memory partition
and shares the processor at different time intervals.
Objectives
To measure the total compute time and the amount of
compute time used by each of three protected memory
partitions and the amount of compute time used by the
system’s supervisory program.
Wiring
The wiring for this example is shown in Figure 34.
Summary
The counter results are:
Counter 8:
Counter 9:
Counter 10:
Counter 11:
Counter 12:
9,925,541,174
1,432,154,273
2,418,010,710
2,943,892,715
3,131,483,476
Total complete
Supervisor
Partition 1
Partition 2
Partition 3
Additional functions may be derived by using the
formulas in Example 1. The numeric values shown in this
example are for illustration only and are not to be
interpreted as standard cases.
26
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