Task Management
The task management service routines provide three kinds
task execution control, task synchronization, and
communicaticn.
of services:
task-to-task
Task execution control includes initiating and terminating tasks. In
general, theonly task to request these services is the REX system control task, which is described below. Task execution control also
includes the dispatcher,DMTDSP, which activates task execution as secn
as that task is initiated and while the task is active.
Task synchronization comprises amechanism by which tasks are made ready or not ready for execution. When a task requests the services cf
another task, the requestor task may suspend its execution while the
request is being processed. The synchronization mechanism that
accomplishes this consists of two routines, and DMTPST. DMTWAT causes the requestor task to temporarily halt execution. DMTPST causes
a temporarily-halted task to resume execution. For more information cn
task synchronization refer to the section "Synchronizing and Dispatching
Tasks"
There are tvo types of task-to-task communications: (1) theDMTSIG routine (ALERT) and (2) the DMTGIV and DMTAKE routines (GIVE/TAKE). The DMTSIG
task topass asynchronous
Functionally,
instruction.
routine allows a task to immediately interrupt another
it information. The interrupted taskmust have an
exit routine defined to handle the interruption.DMTSIG performs a function analagous to an SVC The DMTGIV and DMTAKE routines allow tasks to exchange informaticn
buffers with other tasks. TheGIVE/TAKE function provides the means fer
organized enqueuing and delivery of requests for services or informaticnfrom one task to another.
For more information on task-to-task communications, refer to the
section "Task-to-Task Communications" in this section.liO Management I/O management for tasks consists of the following functions: • Handling requests for I/O operations • Handling 1/0 interrupts • Starting an I/O operation • Completing an I/O request Whenever a task requests the services of the I/O manager, that task builds an I/O request table to be passed to the 110 manager. This table
consists of the following information:• A synchrcnization lock for signaling I/O completion • The address of the device on which the I/O operation is to take place • The number of SENSE bytes to be returned, when applicable • The address of the channel program to be executed RSCS Introduction 3-9
The task management service routines provide three kinds
task execution control, task synchronization, and
communicaticn.
of services:
task-to-task
Task execution control includes initiating and terminating tasks. In
general, the
includes the dispatcher,
as that task is initiated and while the task is active.
Task synchronization comprises a
another task, the requestor task may suspend its execution while the
request is being processed. The synchronization mechanism that
accomplishes this consists of two routines,
a temporarily-halted task to resume execution. For more information cn
task synchronization refer to the section "Synchronizing and Dispatching
Tasks"
There are tvo types of task-to-task communications: (1) the
task to
Functionally,
instruction.
routine allows a task to immediately interrupt another
it information. The interrupted task
exit routine defined to handle the interruption.
buffers with other tasks. The
organized enqueuing and delivery of requests for services or informaticn
For more information on task-to-task communications, refer to the
section "Task-to-Task Communications" in this section.
consists of the following information: