JPH06242968A - Task stopping method in man-machine interface - Google Patents

Abstract

PURPOSE:To prevent the delay of screen extension by forcibly stopping a stoppage object task by a realtime multi-task OS (abbreviated simply as OS hereafter) when a task stopping request is generated. CONSTITUTION:The OS checks the I/O waiting conditions of the stoppage object task and sets an I/O request cancellation flag when it is waiting for I/O. Then, the resource acquisition conditions of the stoppage object task are checked and resources are released when the acquired resources are present. Finally, the chain connection conditions of the task control block (abbreviated as TCB hereafter) of a stopped task are checked, and when a chain is connected, the TCB is cut off from the chain, the TCB is initialized and the new task is switched and thus, a task stopping processing is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a man-machine interface operating under a real-time multitasking OS (hereinafter simply referred to as OS), which is used as a monitoring system for steel / chemical / papermaking plants and the like. Regarding the method of stopping tasks.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a method of stopping a task in a man-machine interface is such that when a stop request is issued to a certain task, the stop target task receives the stop request and releases the acquired resources. After the termination processing is performed, the task to be stopped is stopped by calling the task stop processing of the OS.

[0003]

However, in the conventional technique, when the task to be stopped is in the I / O wait state or the resource acquisition waiting state in the normal processing of the task (2 in FIG. 5), the above-mentioned termination is performed. There is a problem that the task cannot be stopped because the stop processing cannot be executed and the subsequent screen development is delayed. Therefore, an object of the present invention is to prevent the above delay of screen development by forcibly stopping the task to be stopped by the OS when a task stop request is issued.

[0004]

In order to solve the above problems, the present invention forcibly stops a task by the processing procedure shown in FIG. That is, the OS checks the I / O wait status of the task to be stopped (15 in FIG. 1), and sets the I / O request cancel flag if the I / O wait is in progress (16 in FIG. 1). Next, the resource acquisition status of the task to be stopped is checked (17 in FIG. 1), and if there is a resource being acquired, that resource is released (18 in FIG. 1). Finally, the chain connection status of the task control block (abbreviated as TCB below) of the stopped task is checked (19 in FIG. 1), and if the chain is connected, the TCB is disconnected from the chain (2 in FIG. 1).
0), the TCB is initialized (21 in FIG. 1), and the task is switched to a new task (22 in FIG. 1) to complete the task stop processing.

[0005]

By the above means, the OS receives the task stop request, executes the task I / O request cancel processing and the resource release processing, and then initializes the TCB of the stop target task and forcibly stops it. The task is immediately stopped regardless of the state of the task to be stopped.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows I / O request cancellation processing (16 in FIG. 1).
FIG. 6 is a diagram for explaining the details of FIG. In FIG. 2, when an I / O request is generated in the application task (26), the application task (26), that is, the request source task (26) stores an I / O request information buffer (27) in the I / O request information buffer (27).
/ O request parameter (29), request source task number (2
8) Set. The processing of the 1 / O management task will be described below with reference to FIG. FIG. 3 is a flowchart showing the processing of the 1 / O management task. I / O management task (25)
Checks the I / O request information buffer (27), and if the request is set, I / O request parameter (29)
Is read and I / O processing is executed according to the contents. However, at this time, if the task stop information (30) is set to task stop, it is determined that the request source task has already stopped, and the I / O processing is not executed. I when the execution is completed
The / O request source task number (28) is checked, and the request source task (26) is notified of the end. However, if task stop information (30) is set to task stop at this time,
It is judged that the request source task has already stopped, and no completion notification is issued. When a task stop request is issued, the OS (24) checks the request source task number (28) of the I / O request information buffer (27) so that the stop target task has issued the I / O request. For example, the task stop information (30) is set to notify the invalidity of the I / O request. By these processes, even if the task to be stopped is in I / O wait, the OS
Can immediately stop the task to be stopped simply by setting the stop information. Further, FIG. 4 is a diagram for explaining details of the acquisition resource release processing (18 in FIG. 1). When a task is forcibly stopped, the resources that the task had acquired may not be released and may be stopped. Therefore, the OS needs to perform a process of searching a resource acquired by the task and releasing the acquired resource when the task is stopped. Therefore, as indicated by reference numeral 41 in FIG. 4, information on the task number of the resource being acquired is added to each resource acquisition chain. As a result, the OS can release the resources acquired by the task to be stopped.
Following these processes, the TCB is disconnected from the chain (20 in FIG. 1). The task stop is completed by disconnecting the TCB of the task to be stopped from the chain, initializing the TCB, and executing the task change.

[0007]

As described above, according to the invention, in the task stop processing of the man-machine interface, O
Since S executes the I / O cancel processing of the stop target task and the release processing of the acquired resource, the stop processing can be executed immediately regardless of the state of the stop target task. Therefore, the screen is switched due to the delay of the task stop processing. There will be no delay.

[Brief description of drawings]

FIG. 1 is a flow of task stop processing according to the present invention.

FIG. 2 I / O execution processing

[FIG. 3] Processing flow of I / O management task

[Figure 4] Structure of resource acquisition chain

FIG. 5: Flow of task stop processing according to conventional technology

Claims (1)

[Claims] 1. A man-machine interface operating under a real-time multitasking OS, comprising:
A method of stopping a task in a man-machine interface, characterized in that the application task is forcibly stopped by the following procedure. 1) The OS checks the I / O wait status of the task to be stopped, and sets the I / O request cancel flag if the I / O wait is in progress. 2) Next, the resource acquisition status of the task to be stopped is checked, and if any resource is being acquired, that resource is released. 3) Finally, check the chain connection status of the task control block of the task to be stopped, disconnect the task control block from the chain if the chain is connected, initialize the task control block, and switch to a new task. This completes the task stop processing.