CP6100 I/O Process Programming Manual

Using CP6100: Managing Lines
Balancing the Communication Workload
One way to balance the communication workload is to change the
distribution of work between the CPUs or controllers in a 6100
subsystem. CMI has commands that accomplish this end by
causing different kinds of path switches.
| SINGLE-PORT CONTROLLERS. The single-port controllers environment
| appears to SYSGEN as if only one controller were installed and,
| therefore, has no alternate path. Thus, you cannot configure I/O
| processes on different paths in the SYSGEN file (CONFTEXT).
|
| Also, if you alter an I/O process to the other path, a CPU switch
| always results.
|
| Because each controller in the single-port configuration can be
| physically associated with only one CPU, the CSM process ignores
| any CMI commands that request a CPU switch. Any such requests
| are completed with "FEOK" to prevent any existing user startup
| obey files from aborting.
DUAL-PORT CONTROLLERS. To switch control of a set of lines to
another CPU, without switching to the other controller in the
6100 subsystem, you use the CMI ALTER CIU command with the CPU
option. The command switches all lines whose primary path is
through the specified controller; it also switches the CSM if the
controller is primary for path A. (See the description of the
PATHS paragraph in the SYSGEN configuration file.) To specify
the controller in the ALTER CIU command, give the logical device
name of the CSM process pair, followed by #A or #B for path A or
path B. Figure 3-4 shows the command syntax and the effects of
the switch.
October 1985
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