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TUNE
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)
Syntax
{;CQ=qinfo}
TUNE [minclockcycle] {;DQ=qinfo} [...]
{;EQ=qinfo}
Where qinfo is written in the following form:
[base [,[limit][,[min][,[max][,DECAY ],[tslice]]]]]
[ [ [ [ [,OSCILLATE] ]]]]
NOTE Misuse of this command can significantly degrade system operating
efficiency.
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 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 must be set to a multiple 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.
A process in the CS, DS, or ES scheduling subqueues typically begin
execution at the base priority. When the 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,
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 DS and ES subqueues have their bounds set to the
same value.
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
recommended settings are listed in the table below.
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
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
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.
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
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
Related Information
Commands SHOWQ, ALTPROC, SHOWPROC, NEWWG, ALTWG, PURGEWG, SHOWWG
Manuals MPE/iX Intrinsics Reference Manual (32650-90028)