Generated from C.65.00 /SYSADMIN/PUB/MYCICAT last modified on Sun Aug 29 15:08:37 2004
Alters the scheduling characteristics of an existing workgroup. To alter the membership criteria (and create a new workgroup), use the NEWWG command.
ALTWG [WORKGROUP=] workgrp [ [;BASE=] base] [ [;LIMIT=] limit] [ [;MINQUANT=] min] [ [;MAXQUANT=] max] [ [;BOOST=] {DECAY } ] {OSCILLATE} [ [;TIMESLICE=] tslice] [ [;MINCPUPCT=] minpercent] [ [;MAXCPUPCT=] maxpercent]
workgrp The name of the workgroup whose scheduling characteristics will be modified. This is a required parameter. Wildcarding is not allowed. base An integer specifying the priority at which processes executing in the specified 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 specified 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. The quantum value determines the rate of priority decay for processes within the workgroup. Values range between 1 and 32,767. 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. The quantum value 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. DECAY Indicates if the workgroup is to demonstrate the default decay behavior associated with circular queues. If set, a process will decay normally to the limit priority and will return to the base priority when the Dispatcher transaction is completed. OSCILLATE Indicates if the workgroup is to demonstrate oscillation. If set, a process will be placed back to the base priority once its priority has decayed to the limit priority, 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 a 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 Indicates the minimum percent of time which the CPU will be made 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 of time 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 percent and that CPU allocation is based on process priority only. maxpercent Indicates the maximum percent of time which the CPU will be made 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 of time 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 obtaining the CPU time their priorities warrant.
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: o at process creation o whenever you change one of the process attributes on which membership can be based o when you explicitly move a process to a workgroup via the ALTPROC command o when you purge a workgroup, and the subsequent purgescan redistributes processes to remaining workgroups o when you add a new workgroup to the current workgroup configuration o 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. Since the Workload Manager uses a first-fit algorithm, other workgroups are not considered once a match is found. The scheduling characteristics define the scheduling policies which govern processes within the workgroup. The MPE/iX Dispatcher is priority-driven, giving a CPU to the highest priority process ready to run. 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 system is configured with five default workgroups, AS_Default, BS_Default, CS_Default, DS_Default, ES_Default. Each of these workgroups represents one of the five scheduling queues, AS through ES. A default workgroup will have a specific queue's scheduling policies and specify that scheduling queue as its only membership criteria. By defining the default workgroups as the last five workgroups in the ordered list, 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. ALTWG is similar in function to TUNE. In fact, there is overlap between the two commands. Both commands maybe used to adjust the scheduling characteristics of the CS_Default, DS_Default, and ES_Default workgroups. The ALTWG command changes scheduling characteristics of a workgroup, not membership criteria. As a result, there is no need for a system-wide scan since workgroup membership has not been changed. Altering the scheduling characteristics of a workgroup will be deferred while a scan (for example, purge-pending) is in progress. The ALTWG command may be issued 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.
The default workgroups are defined by the system and cannot be purged. In fact, only the scheduling characteristics of the CS_Default, DS_Default, and ES_Default workgroups may be modified. User-defined workgroups may be created, altered, and/or purged. However, only the scheduling characteristics of an existing user- defined workgroup may be altered (for example, a user must use NEWWG to change the name or membership criteria of an existing user-defined workgroup).
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.
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 To set the Program_Development workgroup's timeslice to 500 milliseconds, enter: ALTWG Program_Development ;timeslice=500
Commands : NEWWG, PURGEWG, SHOWWG, TUNE, SHOWQ, ALTPROC, SHOWPROC Manuals : MPE/iX Intrinsics Reference Manual (32650-90028) Using the HP3000 Workload Manager (B3879-90001) Back to Main Index