JPH02204838A - Task priority managing system - Google Patents

Abstract

PURPOSE:To decrease the delay of a processing by changing the task priority of a task which is being occupied to the same as the task priority of the subsequent task or the higher priority in a resources occupancy period. CONSTITUTION:With respect to the occupancy request of resources for requesting an exclusive control from a task, an exclusive control module executes the change processing of the task priority of a task which is being occupied and a drawback processing to the task priority saving area 7 of the task priority by executing the queuing processing of a resources occupancy request task using an occupancy waiting pointer 3 by the exclusive control of resources, and comparing the task priority of the task which is occupying the resources and the task for requesting newly the occupancy. Also, in the case of allocating the resources for requesting the exclusive control to the task by first-in first-out, the task which is waiting for the occupancy is also brought to change processing as to the priority. Subsequently, with respect to the occupancy release request of the resources for requesting the exclusive control from the task, a resources release module executes the occupancy release of the resources which are being occupied and the reallocation to the occupancy waiting task, and also, the recovery of the task priority from the task priority saving area 7 of the task which is being occupied. In such a manner, the delay of the processing is decreased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a CP in a multiple programming processing system.
This invention relates to a management method for efficiently allocating U and other resources to tasks.

[Conventional technology]

In conventional multiplex programming systems, the task priorities that determine CPU allocation to tasks are independent of competition between tasks for resources that require exclusive control for allocation to tasks, or as disclosed in Japanese Patent Laid-Open No. 58-10
As described in Japanese Patent No. 7961, when a request to occupy a resource requiring exclusive control is declared, the task priority is changed to the task priority defined for the resource.

[Problem to be solved by the invention]

The above conventional technology does not take into consideration the relationship between the priority of the task that is occupying the resource that requests exclusive control and the priority of the task that subsequently requests occupancy. If a task with a higher task priority than the task occupying the resource makes an occupation request, the processing time according to the task priority of the task occupying the resource first will be spent until the resource is released. There was a problem in which the effect of setting a high task priority was not obtained because the task had to wait.

An object of the present invention is to change the task priority of the occupying task when a task with a higher task priority than the task priority of the occupying task makes an exclusive control request for the resource that is in the occupied state and requests exclusive control. By changing the task priority of later tasks during the resource occupancy period to be the same as or higher than that of later tasks, the task of later tasks with higher task priorities can reduce the delay in processing caused by tasks with lower task priorities.

[Means to solve the problem]

In order to achieve the above purpose, in response to each resource requesting exclusive control shown in FIG. If it is inside, occupancy waiting task pointer 2 for queuing tasks waiting for occupancy to be released;
An occupied task pointer 4 indicating the task occupying the resource is provided. Then, the task priority order 6 defined by the system is shown in the task management table 5 shown in FIG.
A task priority save area 7 is provided for saving.

Further, using the above table, the exclusive control module and the exclusive release module perform exclusive control of the resource and manage the priority of the task when a task occupies a resource requesting exclusive control and requests release.

[Effect]

The exclusive control module performs queuing processing of a resource occupation requesting task using the exclusive control exclusive control wait pointer 3 for a resource occupation request in response to a resource occupation request requesting exclusive control from a task. By comparing the task priority with that of the task for which the occupation request was made, the task priority of the occupied task is changed and the task priority is saved to the task priority save area 7. Furthermore, when resources requesting exclusive control are allocated to tasks on a first-in, first-out basis, tasks that are waiting for exclusive use also have their priorities changed.

The resource release module responds to a resource release request that requests exclusive control from a task by releasing the occupied resource and reallocating it to the task waiting for occupation, and also in the task priority save area for the occupied task. The task priority is restored from 7.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The exclusive control module is a program that performs the following processing when a task makes an exclusive request for a resource that requires exclusive control.

Saves the task priority 6 set in the task management table 5 of the requesting task to the task priority save area 7, and checks *S whether the resource is occupied by another task.
If it is not occupied, the occupied flag is turned on to determine that the resource is occupied, and the task management table 2 of the requesting task is changed to the resource management table of the resource. 1 in the occupied task pointer 4, and allocates the resource to the task that has requested exclusive use. If the resource for which a task has requested occupancy is being occupied by another task, the task for which a new occupancy request has been made is queued in the occupancy waiting task pointer 3 of the resource management table 1 of the resource. Furthermore, the task priorities of the task occupying the resource and the task newly requested are compared. If the task priority of the occupying task is equal to or higher than the task that has made a new occupation request, nothing is processed; however, if it is lower, a new occupation request is made to change the task priority of the task that is occupying the resource. The task priority level 6 of the task management table 2 of the task occupying the resource is changed to the same as the task priority level of the task that occupied the resource.
change. The program processing of the exclusive release processing module that processes an exclusive release request from a task for a resource that also requests exclusive control is shown below. When there is an occupation request from a task that occupies a resource that requests exclusive control, the occupation release module restores the task priority of the task requesting exclusive control by using the task management table 2 of the task that requested exclusive control. The task priority level 6 is restored using the task priority level 6 saved in the task priority level save area 7. Furthermore, it is determined whether there is any other task requesting exclusive use of the resource based on the occupation waiting task pointer in the resource management table 1 of the resource. When there is a task that requests exclusive use of the resource, the task management table 2 of that task is registered in the occupied task pointer 4 of the resource management table 1 of the resource, and at the same time, it is removed from the queue of tasks waiting for exclusive use and the resource is allocated to a new task. .

If there is no task requesting the resource, the occupied flag 2 and the occupied task pointer in the resource management table 1 for the resource are reset.

Next, the task processing completion time when a conflict occurs between tasks with different task priorities for one resource 8 requesting exclusive control according to the embodiment of the present invention will be compared with that before the present invention was implemented. Task 9 It is assumed that tasks 10 and 11 have sequentially higher task priorities, and tasks 9 and 11 compete for resource g8 that requests exclusive control. FIG. 4 α shows the task processing completion time before implementation of the present invention.

The CPU is assigned to task 9 at times j, , O, and occupies the resource 8 for which exclusive control is requested at time 1.

At time 2, the task 11 becomes ready. Therefore, task 11 has a higher task priority than task 9, so C
The PU is assigned to task 11 and task 9 is placed in a wait state. At time 3, task 11 makes a request to occupy resource 8 for which exclusive control is requested, but since task 9 is currently occupying resource 8, task 11 waits to occupy resource 8 for which exclusive control is requested and enters a wait state. Therefore, the CPU is assigned to task 9 again. Task 10 becomes ready at time 4.

Therefore, since task 10 has a higher task priority than task 9, the CPU is allocated to task 10 and task 9 is placed in a wait state. At time 5, the task 10 completes processing and releases the CPU. Since task 11 is waiting to occupy resource 8, which requests exclusive control, the CPU is assigned to task 9, and the process is completed at time 6, and resource 8, which requests exclusive control, is allocated to task 9.
to open. As a result, the task 11 is released from waiting to occupy the resource 8 for which exclusive control is requested, and the process is completed at time 7. Next, FIG. 4 shows the processing completion time of a task when the present invention is implemented. A CPU is assigned to task 9 at time 1, a CPU is assigned to task 9 at time 1.0, and resource 8, which requests exclusive control, is occupied at time 1. At time 2, the task 11 becomes ready. Therefore, since task 11 has a higher task priority than task 9, the CPU is allocated to task 11 and task 9 is placed in a wait state. At time 3, task 11 requests exclusive control of resource 8.
However, since it is being occupied by task 9, it is in a wait state, waiting for the resource 8 for which exclusive control is requested to be occupied. At this time, due to the effect of the present invention, task 9 has the same task priority as task 11. Then, task 10 becomes ready at time 4, when the CPU is assigned to task 9, but since task 9 has a higher task priority than task 10, task switching is not performed and the CPU is assigned to task 9 successively. At time 8, task 9 completes its processing and releases resource 8 for which exclusive control is requested. At that time, the task priority of task 9 returns to its original level due to the effect of the present invention. As a result, the resource 8 that requests exclusive control of the task 11 is released from the waiting state for occupancy and becomes ready. At this time task 1
Between task 0 and task 11, task 11 has a higher task priority, so the CPU is allocated to task 11. At time 9, the processing of task 11 is completed, the resources requesting exclusive control are released, and the CPU is further allocated to task 10.

The processing of task 1o is completed at time 1o.

As shown above, task 11 with the highest task priority
Before implementing the present invention, the process is completed at time 7, but when the present invention is implemented, it is time 9, which means that task 11 is processed preferentially. Furthermore, task switching occurs five times before implementing the present invention, but only four times after implementing the present invention, making it possible to reduce processing overhead due to task switching.

〔Effect of the invention〕

According to the present invention, when multiple tasks compete for a resource requesting exclusive control, the task priority of the task occupying the resource is changed to the highest task priority of the task requesting exclusive control. Therefore, due to contention for resources requesting exclusive control, a task with a high task priority can process the CPU allocation of a task with a low task priority preferentially without waiting for waiting time. Furthermore, by reducing the number of task switches, processing overhead can also be reduced.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a resource management table for resources requesting exclusive control, showing an embodiment of the present invention. FIG. 2 is a configuration diagram of a task management table of tasks. FIG. 3 is a configuration diagram of a resource management table for resources requesting exclusive control. FIG. 4 is a program flow diagram of the exclusive control module and the exclusive release module at the time of an occupation request and a release request. FIG. 4 is an explanatory diagram showing the task processing completion time before and after implementing the present invention. 1... Resource management table, 2... Occupied flag, 3
...Occupied waiting task pointer, 4...Occupied task pointer, 5...Task management table, 6...Task priority, 7...Task priority save area, 8...
Resources requiring exclusive control, 9 to 11 tasks, 0 to 1
0...Processing time. collection of illustrations

Claims (1)

[Claims] 1. In a multiprogramming processing system that allocates CPUs based on task priority and allocates resources other than the CPU that are commonly used by each task exclusively to tasks, it is not possible to occupy resources that require exclusive control. If the priority of the task that currently occupies the resource is lower than the task that later requested the resource, the priority of the task that occupies the resource first is changed to A task priority management method characterized by providing a function of resetting the priority to the same or higher priority than the priority of the task that requested the occupation of a resource.