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Changes scheduling characteristics of the scheduling subqueues. These
characteristics include base and limit priorities, quantum bounds
(min and max), boost property and timeslice. (Native Mode) PARAMETERS | |
- minclockcycle
This parameter is ignored. It appears here for MPE V/E
compatibility only.
- base
An integer from 150 to 255 specifying the priority at which user
processes executing in the CS, DS, and ES scheduling subqueues begin
their Dispatcher transactions. Priority is inversely related to the
integer: a higher-priority process has a lower number.
While the full range is provided for compatibility, avoid
setting the base priority between 150 and 152, since user processes
running at priorities greater than 152 can adversely affect system
performance.
- limit
An integer specifying the lowest priority at which a
process in the CS, DS, or ES scheduling subqueues can execute.
Priority is inversely related to the integer: a higher-priority process
has a lower number. The limit, which can range from 150 to 255,
must be greater than or equal to the base.
- min
The minimum quantum is a lower bound for the dynamically calculated quantum
(average transaction time) value. The quantum value determines the rate of
priority decay for processes within the scheduling subqueue. Values range
between 1 and 32767 milliseconds.
- max
The maximum quantum is an upper bound for the dynamically calculated quantum
(average transaction time) value. The quantum value determines the rate of
priority decay for processes within the scheduling subqueue. Values range
between 1 and 32767 milliseconds. The value of max must be greater than
or equal to the value of min.
- DECAY
Sets the subqueue to the default decay behavior associated with circular
scheduling subqueues. If set, a process decays normally to the
limit priority and returns to the base priority
when the Dispatcher transaction is complete. DECAY is the default boost
property.
- OSCILLATE
Sets the subqueue to oscillate behavior. If set, a process returns to the
base priority once its priority has decayed to the limit of the
subqueue, even if it has not completed a Dispatcher transaction.
- tslice
The timeslice is the number of milliseconds a process in a given subqueue
can hold the CPU. A process that has held the CPU continuously for this
number of milliseconds is interrupted. This value is accurate to the nearest
increment of 100 milliseconds and has a minimum value of 100 milliseconds.
OPERATION | |
The system manager uses the TUNE command to change the characteristics
of the circular scheduling subqueues to more efficiently manage the current
processing load. Processes in the CS, DS, and ES scheduling subqueues typically begin execution
at the base priority. When a process stops (for disk I/O, terminal I/O,
preemption, etc.), the amount of CPU it has consumed is used to determine
its new priority. If the process has completed a Dispatcher transaction,
typically by issuing a terminal read, its priority is reset to the base,
and the quantum value for that workgroup is recalculated. If the process has
exceeded the quantum (filter) value since its priority was last reduced, the
priority is decreased without exceeding the limit priority. If the boost
property for the workgroup is oscillate, process priorities are reset
to the base value once they decay to the limit. The parameters min and max refer to the absolute bounds
of the quantum ("system average quantum" or SAQ), or a filter representing
the average transaction time of processes in that subqueue. The quantum is
recomputed after every user Dispatcher transaction is complete, and then
compared against the CPU time of a process to determine whether the priority
of the process should be decreased. | | | |  | NOTE:
With Release 5.0 of MPE/iX, all three circular scheduling subqueues,
CS, DS, and ES, have dynamically calculated quantums. By default, the
bounds of the DS and ES subqueues are set equal.
| | | | |
If the values specified for max are too large, system response may become
erratic. If they are too small, excessive memory management may occur due
to frequent process swapping. Either case degrades system
performance. The values for min and max may range from 1
to 32,767. The timeslice value determines how long a process in a given scheduling
subqueue will be allowed to hold the CPU. This value is different than the
quantum, which determines how rapidly process priorities decay. The timeslice
does interrupt the process if the process is interruptable.
The timeslice is a multiple of 100 milliseconds and has a minimum value of
100 milliseconds. The following default settings are established when the system is
booted from the system disk (a START RECOVERY or
START NORECOVERY), unless the user has customized a TUNE
configuration .
START RECOVERY or START NORECOVERY
CQ base: 152 DQ base: 202 EQ base: 240
limit: 200 limit: 238 limit: 253
min: 1 min: 2000 min: 2000
max: 2000 max: 2000 max: 2000
boost: DECAY boost: DECAY boost: DECAY
tslice: 200 tslice: 200 tslice: 200
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| | | | | NOTE:
The MPE/iX Scheduler now supports the workgroup concept.
However, backward compatibility is maintained through five
default workgroups created by the system. The scheduling
characteristics of the CS_Default, DS_Default, and ES_Default
workgroups mimic those of the CS, DS, and ES scheduling
subqueues. In fact, changing the scheduling characteristics of the CS, DS, and
ES scheduling subqueues, via the TUNE command, is equivalent to
changing the characteristics of the corresponding default workgroup
through ALTWG. Please refer to the NEWWG and ALTWG
commands for more detail. Workload Manager users should use ALTWG rather than TUNE since TUNE
does not modify user-defined workgroups. If you aren't using
the Workload Manager, and you want to change one of the system-defined
workgroups, you may wish to use ALTWG because it only examines member
processes of a specific workgroup and not all processes on the system.
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The TUNE command may be issued from a session, job, program or in BREAK.
Pressing Break has no effect on this command. TUNE requires System
Supervisor (OP) or System Manager (SM) capability. EXAMPLE | |
To set the CS subqueue's base to 152, limit to 200, and max quantum
(filter) to 300; and the DS subqueue's base to 202, limit to 238,
min and max quantum (filter) to 1000, and cause oscillation boosting,
enter:
TUNE CQ=152,200,300,300;DQ=202,238,1000,1000,OSCILLATE
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To set the CS subqueue to oscillation with a 300 millisecond timeslice and the
DS subqueue's base to 180, limit to 238, boost property to decay, and
timeslice to 1500, enter:
TUNE CQ=,,,,OSCILLATE,300;DQ=180,238,,,DECAY,1500
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Related Information | |
- Commands
SHOWQ, ALTPROC, SHOWPROC, NEWWG, ALTWG,
PURGEWG, SHOWWG
- Manuals
MPE/iX Intrinsics Reference Manual (32650-90028)
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