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Alters the scheduling characteristics of an existing workgroup. (Native Mode) SYNTAX | |
ALTWG [WORKGROUP=]workgrp
[[;BASE=]base] [[;LIMIT=]limit]
[[;MINQUANT=]min] [[;MAXQUANT=]max]
[[;BOOST=]{DECAY }] {OSCILLATE}
[[;TIMESLICE=]tslice]
[[;MINCPUPCT=]minpercent] [[;MAXCPUPCT=]maxpercent]
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| | | |  | NOTE:
To alter the membership criteria of a workgroup, you must
use the NEWWG command.
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PARAMETERS | |
| | | | | NOTE:
ALTWG follows the CI convention
that positional parameters are allowed until the first high-level
keyword is specified.
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- workgrp
The name of the workgroup whose scheduling characteristics
you are modifying. This is a required parameter. Use of
wildcards is not allowed. - base
An integer from 150 to 255 specifying the highest priority at which
processes executing in the workgroup 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 compatability,
avoid setting the base priority between 150 and 152, since user
processes running at a higher priority than 152 can adversely affect system
performance. - limit
An integer specifying the lowest priority which processes executing in the
workgroup can attain. 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 number of milliseconds that a process may use the CPU before
its priority is reduced. The min is a lower bound for the quantum value,
which determines the rate of priority decay for processes within
the workgroup. Values range between 1 and 32,767, inclusive. - max
The maximum number of milliseconds that a process may use the CPU before its
priority is reduced. The max is an upper bound for the quantum value, which
determines the rate of priority decay for processes within
the workgroup. The value of max must be greater than or equal to the
value of min. Values range between 1 and 32,767, inclusive. - DECAY
Sets the workgroup 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 workgroup to oscillate behavior. If set, a process returns to the
base priority once its priority has decayed to the
limit of the workgroup, even if it has not completed a
Dispatcher transaction. - tslice
The timeslice is the maximum number of milliseconds a process in the
workgroup can hold the CPU before returning to the Scheduler to have its
priority recalculated. Values must be multiples of 100, with a minimum value
of 100 and a maximum value of 32700. - minpercent
The minimum percentage of time that the CPU is available
to the workgroup's member processes. Within the target workgroup, this CPU
time is allocated according to the processes' priorities. The workgroup
is guaranteed this minimum percentage even if higher-priority processes in
other workgroups are ready to run. If the processes in the workgroup do not require as much
CPU time as their guaranteed minimum, that time will be available to processes
in other workgroups. The default value for this optional workgroup
characteristic is that the workgroup is not guaranteed any minimum CPU
allocation and that CPU allocation is based on process priority only. - maxpercent
The maximum percentage of time that the CPU is available
to the workgroup's member processes. The workgroup will be limited to this
maximum percentage of time even if no other process in another
workgroup is ready to run. In other words, a workgroup will be limited to
this maximum percentage even if the system must remain idle for
the remainder of the time. The default value for this optional workgroup characteristic is that there
is no maximum which would prevent a workgroup's processes from getting the
CPU time their priorities warrant.
OPERATION | |
Each workgroup consists of three components, a name, membership criteria,
and scheduling characteristics. The membership criteria
(MEMB_LOGON, MEMB_PROGRAM and MEMB_QUEUE parameters),
determine process assignment, which occurs on six occasions: whenever you change one of the process attributes on which membership
can be based
when you explicitly move a process to a workgroup via the ALTPROC
command
when you purge a workgroup, and the subsequent purgescan redistributes
processes to remaining workgroups
when you add a new workgroup to the current workgroup configuration
when the current workgroup configuration is replaced
Membership conflicts are resolved by assigning a process to the
first workgroup for which it qualifies. (Workgroups are
maintained in an ordered list in which position is important. For more
information, read the discussion of the POSITION parameter of the
NEWWG command, later in this chapter.)
Since the Workload Manager uses a first-fit algorithm,
other workgroups are not considered once a match is found. For this
reason, it is important to arrange the workgroups in your
configuration from those with the most precise membership
criteria to those with more general membership criteria. The scheduling characteristics define the scheduling policies which govern
processes within the workgroup. The MPE/iX Dispatcher is priority-driven,
allocating a CPU to the highest priority process that is ready to run.
The MPE/iX Scheduler determines process priorities in accordance with
workgroup scheduling characteristics. Each
workgroup has a base and a limit, defining the priority range for
processes within that workgroup. Processes will begin their Dispatcher
transactions at the base priority and decay towards the limit priority
as they consume system resources. The process priority will never drop below
the limit of the workgroup. If the boost property of the workgroup is set
to oscillate, the process priority will be reset to the base priority
when it decays to the limit priority. Processes completing Dispatcher
transactions (typically via a terminal read) are reset to the base
priority. Each of the five system-defined workgroups represents one of the five
scheduling subqueues, AS, BS, CS, DS and ES. Their
only membership criteria is the scheduling queue
attribute. For example, the AS_Default workgroup has as its membership
criteria MEMB_QUEUE=AS. These workgroups appear last
in the ordered list so that the Scheduler can guarantee that all
processes will be assigned to a workgroup. The ALTWG command allows a user to alter only the scheduling
characteristics of an existing workgroup, not the membership
criteria. As a result, there is no need for a system-wide scan since
workgroup membership does not change. (To change
the name or membership criteria of an existing user-defined workgroup,
you must use NEWWG.) ALTWG is similar in function to TUNE. In fact, if you need to
adjust the scheduling characteristics of the CS_Default, DS_Default,
and ES_Default workgroups, you may use the TUNE command (instead
of ALTWG) to do so. Altering the scheduling characteristics of a
workgroup will be deferred while a scan is in progress. You may issue the ALTWG command from a session, job, program or
in BREAK. Pressing Break has no effect on this command.
ALTWG requires System Supervisor (OP) or System Manager (SM) capability. | | | | | NOTE:
Altering the scheduling characteristics of a workgroup will affect each
of the member processes. That is, the Scheduler might need to adjust
each process' priority attribute. The time required
to make these priority adjustments is related to the number of
processes in the workgroup.
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EXAMPLE | |
To set the Program_Development workgroup's base to 158, limit to 168,
and boost priority to decay, enter:
:ALTWG Program_Development, 158, 168, , , decay
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To set the Program_Development workgroup's timeslice to 500 milliseconds,
enter:
:ALTWG Program_Development ;timeslice=500
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Related Information | |
- Commands
NEWWG, PURGEWG, SHOWWG, TUNE, SHOWQ,
ALTPROC, SHOWPROC
- Manuals
MPE/iX Intrinsics Reference Manual (32650-90028)
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