JP2000172514A - Task management device and task scheduling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a low priority task to have the processing opportunity of preset time while keeping a real time property for the task of high priority by switching a ready state and a wait state only for the task of priority specified in a time sharing priority range. SOLUTION: A data processor operated by program control and a storage device for storing information are provided for the management device. The storage device is provided with a ready queue 20 for storing the information of an executable task for each priority, a time sharing wait queue 40, the time sharing priority range 41 and a time sharing time table 43, etc. The data processor is provided with a means 10 for switching an execution task, a task group switching means 30 and a switching time detection means 31. Then, relating to this device, only for the task of the priority specified in the time sharing priority range 41, the task group switching means 30 switches the ready state and the wait state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a task schedule management technique, and more particularly to a task management apparatus and a task scheduling method for executing priority scheduling used in a real-time OS.

[0002]

2. Description of the Related Art Conventionally, a real-time OS has been adopted in an application product of an embedded microcomputer as a system is being scaled up and integrated. In many real-time OSs, task schedule management is performed by a task management device and a task scheduling method.

In prior art task management apparatuses and task scheduling methods, it is important to design priority assignment of tasks. In general, tasks that are urgent due to hardware constraints have higher priorities, and tasks that are not urgent have a higher priority. Set a low priority. When considering the feasibility of the system, it is necessary to consider and adjust the priority and processing time for the high-priority tasks of all modules to determine whether the time constraint can be cleared. However, the priority of low priority tasks,
Coordinating processing time between all modules reduces productivity, and less time is required because re-adjustment must be performed between all tasks every time a combination of modules changes during reuse. .

First, a conventionally used task scheduling method will be described. FIG. 9 is a block diagram for explaining a conventional task management device. As shown in FIG. 9, the conventional priority scheduling method includes:
Execution task switching means (execution task determination means) 10
And a ready queue 20 for storing information on executable tasks for each priority.

[0005] The execution order of the tasks in the state of the ready queue 20 shown in FIG. 10 will be described. FIG.
10 illustrates a state of a ready queue for explaining an execution order of tasks executed by the task management device of FIG. 9; FIG.
As indicated by 0, the execution task selected by the execution task switching means 10 is the task 1A having the priority 3.
When the task 1A is completed, the task 1B, the task 1C, and the task 2A are arranged in the priority 4 in the order in which the tasks can be executed. Therefore, the data processing device selects the task 1B and executes it. Thereafter, the order of tasks to be executed is task 1C → task 2A → task 2B → task 2C.

Next, a task scheduling method other than the priority scheduling method will be described. An example of a task scheduling method based on time sharing that has been developed in large computers and the like is disclosed in Japanese Patent Laid-Open No. 9-1.
98261. In other words, the prior art has a means for setting the processing priority of the peripheral input / output device for each task separately from the schedule priority of the task for the CPU, so that the task requiring real-time processing can be processed preferentially. Means for setting, from an operating system, a processing priority on an input / output processing wait queue for a peripheral input / output device for each task, irrespective of the scheduling priority of the task with respect to the CPU; Means for setting the priority of task scheduling at the time of completion of input / output from the operating system from the operating system, and the processing priority on the input / output processing wait queue does not require real-time processing and is not processing performed in the background. It is described that setting is made differently between tasks . As a result, tasks requiring real-time properties are processed with priority over other tasks, including output processing to peripheral devices, so real-time properties are further improved.
It describes that a task that executes batch processing in the background has an effect that it can be processed without significantly affecting the performance of other tasks, including input and output to peripheral devices.

[0007]

However, the prior art has the following problems.

The first problem is that, in the task scheduling method, when independently designed modules are combined, the task of the own module may not behave as expected due to the influence of the task of another module. That is. The reason for this is that if a task that was previously executable at a certain priority takes a long time to process, then a task of the same priority that becomes executable at a later time will last until the previous task is completed. This is because no processing is performed.

A second problem is that in the time sharing task scheduling method, processing that requires hard real-time processing cannot be performed in time. The reason is that the task is switched at regular intervals, so it is possible to respond to events that occur during the task,
After a certain period of time. If the fixed time is shortened for the purpose of improving the real-time property, the overhead of the task switching time increases, which is not suitable for embedded use.

[0010] The present invention has been made in view of such a problem, and an object thereof is to provide a real-time OS.
The present invention is to provide a task management device and a task scheduling method for exchanging a ready state and a wait state of a task having a limited range of priority at a designated time in the priority scheduling used in the above.

[0011]

According to a first aspect of the present invention, there is provided a task management device for executing a priority scheduling, wherein the task management device executes the priority scheduling.
A data processing device having a function of exchanging a ready state and a wait state of a task having a predetermined range of priority based on a designated time and a storage device for storing information; Queue for storing information of each priority, a time-sharing wait queue for storing information of a part of the ready queue, and a time-sharing priority range for storing upper and lower priorities for performing time sharing. An active task group that stores a task group number being executed, and a time sharing time table that stores processing time information for each task group, wherein the data processing device includes:
Executing task switching means for selecting and executing the highest priority task from the executable tasks stored in the ready queue, and executing the task in the range designated by the time sharing priority range to the ready task. A task group switching unit for evacuating the queue from the queue to the time-sharing wait queue and returning the next group of tasks evacuated to the time-sharing wait queue to the ready queue; And a switching time detecting unit that activates the task group switching unit after waiting for the elapse of the time stored in the time sharing time table. Exist. The gist of claim 2 of the present invention is that the time-sharing wait queue includes at least all tasks in an area for temporarily saving tasks in a range specified by the time-sharing priority range from the ready queue. 2. The task management device according to claim 1, wherein the task management device is configured to store only a group. The gist of claim 3 of the present invention is characterized in that the executed task switching means is configured to refer to the ready queue and select and execute a task with a high priority. The task management device according to claim 1 exists. According to another aspect of the present invention, when there are a plurality of tasks having the same priority, the execution task switching unit is configured to select and execute a task that is in a ready state first. The task management device according to claim 1, wherein Claim 5 of the present invention
The gist of the above is that the task group switching means,
A task in a range specified by the time sharing priority range is saved from the ready queue to the time sharing wait queue, and the next group of tasks is returned to the ready queue. The task management device according to claim 1.
The gist of claim 6 of the present invention is that the switching time detecting means obtains information of a group number currently being executed from the active task group, and processes time information of the group from the time sharing time table. 2. The task management device according to claim 1, wherein the task management device is configured to activate the task group switching means when the time when the information has been obtained elapses. The gist of claim 7 of the present invention is that the ready queue is configured to store ready tasks for each priority. Exist. According to another aspect of the present invention, there is provided a task scheduling method for executing a priority scheduling, wherein when executing the priority scheduling, a ready state and a wait state of a task having a predetermined range of priorities are designated. A data processing step having a function of exchanging based on the performed time and a storage step of storing information, wherein the storage step is a ready queue storage step of storing information on executable tasks for each priority, A time-sharing wait queue storing step for storing a part of information of the ready queue storing step, a time-sharing priority range storing step for storing upper and lower priorities for performing the time sharing, and a task group number being executed Active task group storing step of storing the processing time and processing time information for each task group An im-sharing time table storage step, wherein the data processing step is an execution task switching step of selecting and executing the highest priority task from among the executable tasks stored in the ready queue storage step. The tasks in the range specified in the time sharing priority range storing step are saved from the ready queue storing step to the time sharing wait queue storing step, and are also saved in the time sharing wait queue storing step. A task group switching step of returning a task of the next group to the ready queue storage step, and determining a current task group based on the active task group storage step, and storing the current task group in the time sharing time table storage step. Wait for the elapse of time Serial resides in task scheduling method characterized by comprising a switching time detecting step of starting the task group switching step. The gist of the ninth aspect of the present invention is that the time sharing wait queue storing step temporarily saves a task in a range specified in the time sharing priority range storing step from the ready queue storing step. 9. The method according to claim 8, further comprising the step of storing at least all task groups in an area. According to a tenth aspect of the present invention, the executed task switching step includes a step of referring to the ready queue storing step and selecting and executing a task with a high priority. Item 8 is the task scheduling method. The gist of claim 11 of the present invention is characterized in that, when there are a plurality of tasks having the same priority, the executed task switching step includes a step of selecting and executing the task which is in the ready state first. A task scheduling method according to claim 8. The gist of the twelfth aspect of the present invention is that, in the task group switching step, the tasks in the range specified in the time sharing priority range storage step are stored from the ready queue storage step to the time sharing wait queue storage. 9. The task scheduling method according to claim 8, further comprising a step of saving to a step and returning a next group of tasks to the ready queue storing step. The gist of claim 13 of the present invention is that the switching time detecting step obtains the group number information of the currently executing group from the active task group storing step and converts the processing time information of the group to the time sharing time. 9. The task scheduling method according to claim 8, further comprising a step of starting from the table storage step and activating the task group switching step when the obtained time elapses. The gist of claim 14 of the present invention resides in the task scheduling method according to claim 8, wherein the ready queue storing step includes a step of storing a ready state task for each priority. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A task management device and a task scheduling method according to first and second embodiments described below have a priority used in a real-time OS (operating software for real-time processing: often referred to as RTOS). The degree scheduling is characterized in that a ready state and a wait state of a task having a certain priority within a limited range are switched at a designated time.
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First Embodiment) FIG. 1 is a functional block diagram for explaining a first embodiment of the task management device of the present invention. Referring to FIG. 1, the task management device according to the first embodiment includes a data processing device 1 (subject of execution of a data processing step) that operates under program control, a storage device 2 that stores information (subject of execution of a storage process). It has.

The storage device 2 stores information on executable tasks for each priority (a task in a ready state is stored for each priority). A time-sharing wait queue 40 for storing a plurality of partial information (the subject of executing the time-sharing wait queue storing step), and a time-sharing priority range 41 for storing the upper and lower priorities for performing the time sharing (time sharing). The executing entity of the ring priority range storing step), the active task group 42 storing the number of the task group being executed (the executing entity of the active task group storing step), and the time sharing time table storing the processing time information for each task group 43 (Executing entity of the time sharing time table storage step) It is equipped with a.

Time sharing weight queue 40
In the area for temporarily saving the tasks in the range specified by the time sharing priority range 41 from the ready queue 20, all the task groups can be stored.

The data processing apparatus 1 includes an execution task switching unit (indicated as an execution task determination unit in the figure) 10, a task group switching unit 30, and a switching time detection unit 31.
It has.

The execution task switching means 10 is an execution subject of the execution task switching step, and includes a ready queue 20.
The task having the highest priority is selected from the executable tasks stored in the. Further, when there are a plurality of tasks having the same priority, the tasks that can be executed first are executed first. Specifically, the execution task switching unit 10 refers to the ready queue 20 to select and execute a task with a high priority. When there are a plurality of tasks having the same priority, the task which is in the ready state first is selected and executed.

The task group switching means 30 is a subject of execution of the task group switching step, and evacuates tasks in the range specified by the time sharing priority range 41 from the ready queue 20 to the time sharing wait queue 40, The task of the next group saved in the time sharing wait queue 40 is returned to the ready queue 20. Specifically, the task in the range specified by the time sharing priority range 41 is evacuated from the ready queue 20 to the time sharing wait queue 40, and the task of the next group is returned to the ready queue 20. In this manner, the ready state and the wait state of a task having a limited range of priority can be switched.

The switching time detecting means 31 is a subject that executes the switching time detecting step, and determines the current task group based on the active task group 42.
When the time stored in the time sharing time table 43 has elapsed, the task group switching means 30 is activated. Specifically, the group number information of the group currently being executed is obtained from the active task group 42, and the processing time information of the group is stored in the time sharing time table 43.
You can know from. Further, the task group switching means 30 is activated when the time obtained has elapsed.

Next, the overall operation of the present embodiment will be described in detail with reference to FIGS. FIG. 2 is a flowchart for explaining a task scheduling method executed by the execution task switching means 10 of FIG. First, when a change occurs in the task state, the execution task switching unit 10 determines an execution task. The execution task switching means 10 obtains the highest priority information of the currently executable task based on the ready queue 20 (step F10 in FIG. 2). Next, based on the ready queue 20, a task number having the highest priority is obtained (step F11 in FIG. 2), and the task number is compared with the task number currently being executed to see if they match (step F12 in FIG. 2). ).
If they match, it is determined that the current task is a continuation, and the processing jumps to the original task processing. If they don't match,
The information of the task being executed is stored (step F13 in FIG. 2), and the number of the task being executed is updated (step F13 in FIG. 2).
14) Then jump to the new task process.

When the processing time corresponding to the active task group 42 has elapsed, the switching time detecting means 31
The task group switching means 30 is called.

The task group switching means 30 first refers to the time sharing priority range 41, and moves the task information in the priority range from the ready queue 20 to the time sharing wait queue 40. Next, the active task group 42 is updated, and the task information of the new task group is moved from the time sharing wait queue 40 to the ready queue 20. Finally, the processing time of the new task group is set with reference to the time sharing time table 43.

Next, a specific example will be described. FIG.
When there are two task groups, before and after the task group switching by the task group switching means 30,
The state of the active task group 42, the ready queue 20, and the time sharing wait queue 40 are shown.

First, the state before switching will be described. The active task group 42 (denoted by 110 in FIG. 4) is 1 and the ready queue 20 (210 in FIG. 4)
In the priorities 3 and 4 of “group 1”, tasks 1A, 1B, and 1C, which are tasks of group 1, are stored as executable states. On the other hand, the two tasks that are not currently active include the group 2 of the time-sharing wait queue 40 (410 in FIG. 4).
Task 2A, task 2
B and task 2C are stored as wait states.
It should be noted that the time sharing priority range 41 is priority 3 to 6.

FIG. 3 is a flowchart for explaining a task scheduling method executed by the task group switching means 30 of FIG. The task group switching means 30 includes an active task group 42 (FIG. 4).
In this case, the group information to be saved is 1 (step F20 in FIG. 3). next,
With reference to the time sharing priority range 41, information of priority 3 to 6 is obtained as reference position information of the ready queue 20 (step F21 in FIG. 3). Further, the task information in the time share range is acquired from the ready queue 20 (210 in FIG. 4), and the task information is moved to the wait queue of the group to be saved in the time sharing wait queue 40 (step F22 in FIG. 3). The information moved at this time is stored in the time sharing wait queue 40 (FIG. 4).
(420 in FIG. 4) for group 1 (421 in FIG. 4). Next, the active task group 42 (denoted by 120 in FIG. 4) is updated to 2 (step F2 in FIG. 3).
3) The task information of group 2 is returned from the time sharing wait queue 40 (denoted by 410 in FIG. 4) for group 2 (412 in FIG. 4) to the ready queue 20 (denoted by 220 in FIG. 4) (Step F2 in FIG. 3)
4). At this time, the time-sharing wait queue 40 (shown as 411 in FIG. 4) having no task is replaced with the time-sharing wait queue 40 (shown as 422 in FIG. 4).
To return to. Finally, the processing time of this group is set with reference to the time sharing time table (FIG. 3).
Step F25).

Thus, the task group switching is completed. In the state after the switching, the active task group 42 (denoted by 210 in FIG. 4) has a priority of 2, and the ready queue 20 (denoted by 220 in FIG. 4) includes tasks of group 2 in priority 3 to 6. Is task 2
Tasks such as A, task 2B, and task 2C are stored as executable states. On the other hand, the tasks of group 1 that were active before the switching are tasks 1A and 1A for group 1 (denoted by 421 in FIG. 4) of the time-sharing wait queue 40 (denoted by 420 in FIG. 4).
Task 1B and task 1C are stored as wait states.

As described above, according to the first embodiment, first, only the tasks having the priority specified in the time-sharing priority range 41 are set by the task group switching means 30 between the ready state and the wait state. Since it is replaced,
For high-priority tasks that require real-time processing, the conventional real-time performance is maintained, while for low-priority tasks, processing is performed for a preset time for each of the divided task groups. Opportunities can be provided. Second
In addition, since the task group switching means 30 switches the ready state and the wait state for each of the divided task groups, the task of low priority can be designed on the assumption that a processing opportunity of a preset time is given. ,
It is not necessary to adjust the priority and the processing time between modules (between task groups), so that it is possible to design modules with high independence, and to promote the implementation of software components.

(Second Embodiment) Next, a second embodiment of the present invention will be described in detail with reference to the drawings. FIG.
It is a functional block diagram for explaining a 2nd embodiment of the task management device of the present invention. Referring to FIG. 5, in the task management device of the second embodiment, the data processing device 1 includes a switching time timer management unit 32 in addition to the configuration of the data processing device 1 of the first embodiment shown in FIG. The feature is that it has.

When the task being executed is outside the time sharing priority range 41, the switching time timer management means 32 temporarily stops the switching time timer of the switching time detection means 31, and the time sharing priority range 41 Restarts the switching time timer. The execution task switching means 10 calls the switching time timer management means 32 after determining the task to be executed, and controls the suspension and restart of the switching time timer.

The operation of the present embodiment will be described in detail with reference to the drawings. FIG. 6 shows the execution task switching means 10 of FIG.
3 is a flowchart for explaining a task scheduling method executed in the step S1. The operation of the task group switching means 30 and the switching time detecting means 31 in FIG. 5 and the configuration of the storage device 2 are the same as those of the switching time detecting means 31 and the switching time timer managing means 32 in the embodiment shown in FIG. Since the configuration is the same as that of the second embodiment, the description is omitted. In the embodiment shown in FIG. 1, even if the task being executed is a task outside the time sharing priority range 41, it is included in the count of the switching time timer. That is, the processing time given to the task group in the switching range is stored in the time sharing time table 43.
Is the time obtained by subtracting the time during which the task having a higher priority than the switching range is being executed from the time stored in the switch. In the case of the present embodiment, the execution task switching means 10
However, after determining the task to be executed, the switching time timer management means 32 is called (step F15 in FIG. 6), and the switching time timer is controlled so that there is no error with the time stored in the time sharing time table 43. ing.

Next, a specific example will be described. FIG.
FIG. 8 is a flowchart for explaining a task scheduling method executed by the switching time timer management means 32 of FIG. 5. FIG. 8 shows a specific example of a task scheduling method executed by the execution task switching means of FIG. . It is assumed that when the execution task switching means 10 determines a task to be executed, the state of the ready queue 20 is as shown in FIG. 8, and the task to be executed is the task 0A of priority 2. The switching time timer management means 32 called from the execution task switching means 10 compares the priority 2 of the task to be executed with the time sharing priority range 41 to determine whether or not the task is in the switching range (step F30 in FIG. 7). . Since the priority 2 is out of the range ("No" in step F30), it is determined whether or not the switching time timer is stopped (step F32 in FIG. 7). If not ("No" in step F32), the switching is performed. The time timer count is stopped (step F34 in FIG. 7). When the execution of the task 0A is completed, the task to be executed next becomes the task 3A of priority 3. Execution task switching means 1
From 0, the switching time timer management means 32 is called after the task to be executed is determined, and the switching range is determined to be within the range (step F3 in FIG. 7) (step F3).
Since the determination of whether the switching time timer is counting (Step F31 in FIG. 7) is “No”,
The counting of the switching time timer is started (step F33 in FIG. 7).

As described above, according to the second embodiment, in addition to the effects described in the first embodiment, the switching time timer management means 32 called by the execution task switching means 10 causes the time sharing priority. Degree range 4
Since the count of the switching time timer is stopped while the task other than 1 is being executed, the time sharing time table 4
There is a new effect that the error with respect to the time set to 3 is reduced.

In the present embodiment, the present invention is not limited to the above-described embodiment, but can be applied to a task scheduling technique executed by a microcomputer suitable for applying the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment,
The number, position, shape, and the like suitable for carrying out the present invention can be obtained. In each drawing, the same components are denoted by the same reference numerals.

[0034]

Since the present invention is configured as described above, the following effects can be obtained. The first effect is that the task group switching means switches between the ready state and the wait state only for the tasks of the priority specified in the time sharing priority range, so that the high priority tasks that require real-time processing can be used. In other words, it is possible to provide a low-priority task with a processing opportunity of a preset time for each of the divided task groups while maintaining the conventional real-time property. The second effect is that the task group switching means switches between the ready state and the wait state for each of the preliminarily divided task groups. Therefore, it is premised that a processing opportunity of a preset time is given to a low priority task. Since the design can be performed, it is not necessary to adjust the priority and the processing time between modules (between task groups), so that it is possible to design a highly independent module unit, and to promote software components.

[Brief description of the drawings]

FIG. 1 is a functional block diagram for explaining a first embodiment of a task management device of the present invention.

FIG. 2 is a flowchart for explaining a task scheduling method executed by an execution task switching unit of FIG. 1;

FIG. 3 is a flowchart for explaining a task scheduling method executed by a task group switching unit in FIG. 1;

FIG. 4 shows states of an active task group, a ready queue, and a time-sharing wait queue before and after task group switching by a task group switching unit when there are two task groups.

FIG. 5 is a functional block diagram for explaining a second embodiment of the task management device of the present invention.

FIG. 6 is a flowchart for explaining a task scheduling method executed by the execution task switching means of FIG. 5;

FIG. 7 is a flowchart for explaining a task scheduling method executed by the switching time timer management means of FIG. 5;

8 shows a specific example of a task scheduling method executed by the execution task switching means of FIG.

FIG. 9 is a block diagram for explaining a conventional task management device.

10 shows a state of a ready queue for explaining an execution order of tasks executed by the task management device of FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Data processing device 2 ... Storage device 10 ... Execution task switching means 20 ... Ready queue 30 ... Task group switching means 31 ... Switching time detection means 32 ... Switching time timer management means 40 ... Time sharing wait queue 41 ... Time sharing Priority range 42: Active task group 43: Time sharing time table

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Claims (14)

[Claims] 1. A task management device for executing priority scheduling, wherein when performing priority scheduling, a function of exchanging a ready state and a wait state of a task having a predetermined range of priorities based on a designated time. And a storage device for storing information, the storage device comprising: a ready queue for storing information on executable tasks for each priority; and a time for storing information on a part of the ready queue. A sharing weight queue, a time sharing priority range for storing upper and lower priorities for performing time sharing, an active task group for storing a task group number being executed, and processing time information for each task group. A time-sharing time table to be stored, wherein the data processing device comprises: Execution task switching means for selecting and executing the task with the highest priority from the executable tasks stored in the queue, and executing the tasks in the range specified by the time sharing priority range from the ready queue. Task group switching means for saving to the time sharing wait queue and returning the next group of tasks saved to the time sharing wait queue to the ready queue; and a current task based on the active task group. A task management device, comprising: a switching time detecting unit that determines a group and waits for a lapse of time stored in the time sharing time table to activate the task group switching unit. 2. The time-sharing wait queue is configured to store at least a task in a range designated by the time-sharing priority range from the ready queue for at least all task groups in an area for temporarily saving the tasks. The task management device according to claim 1, wherein 3. The task management system according to claim 1, wherein the execution task switching unit is configured to refer to the ready queue and select and execute a task having a high priority. apparatus. 4. The execution task switching means according to claim 1, wherein, when there are a plurality of tasks having the same priority, a task which is in a ready state first is selected and executed. A task management device according to claim 1. 5. The task group switching means saves a task in a range specified by the time sharing priority range from the ready queue to the time sharing wait queue, and transfers a task of the next group to the ready queue. The task management device according to claim 1, wherein the task management device is configured to return to task. 6. The switching time detecting means obtains information on a group number currently being executed from the active task group, obtains processing time information of the group from the time sharing time table, and obtains the obtained time. 2. The task management device according to claim 1, wherein the task group switching unit is activated when a time elapses. 7. The task management device according to claim 1, wherein the ready queue is configured to store ready tasks for each priority. 8. A task scheduling method for executing a priority scheduling, wherein a function of exchanging a ready state and a wait state of a task having a predetermined range of priorities based on a designated time when executing the priority scheduling. And a storage step of storing information. The storage step includes: a ready queue storage step of storing information on executable tasks for each priority; and information of a part of the ready queue storage step. , A time-sharing priority queue storing step of storing upper and lower priorities for performing time sharing, and an active task group storing step of storing a task group number being executed. And time sharing time for storing processing time information for each task group A table storage step, wherein the data processing step is an execution task switching step of selecting and executing a task having the highest priority from among the executable tasks stored in the ready queue storage step, and the time The task in the range specified in the sharing priority range storage step is saved from the ready queue storage step to the time sharing wait queue storage step, and the next group saved in the time sharing wait queue storage step is saved. A task group switching step of returning the current task to the ready queue storing step; determining a current task group based on the active task group storing step; and lapse of time stored in the time sharing time table storing step. Wait for the task group A switching time detecting step of starting a switching step. 9. The time-sharing wait queue storing step includes storing at least all task groups in an area for temporarily saving tasks in a range specified in the time-sharing priority range storing step from the ready queue storing step. 9. The method according to claim 8, further comprising the step of storing 10. The task scheduling method according to claim 8, wherein the execution task switching step includes a step of referring to the ready queue storage step and selecting and executing a task with a high priority. . 11. The execution task switching step according to claim 8, wherein, when there are a plurality of tasks having the same priority, a task which has been brought into a ready state first is selected and executed. Task scheduling method. 12. The task group switching step,
Saving the tasks in the range specified in the time sharing priority range storing step from the ready queue storing step to the time sharing wait queue storing step, and returning the next group of tasks to the ready queue storing step; The task scheduling method according to claim 8, comprising: 13. The switching time detecting step obtains information on a currently executing group number from the active task group storing step, and obtains processing time information of the group from the time sharing time table storing step. 9. The task scheduling method according to claim 8, further comprising the step of activating said task group switching step when a learned time elapses. 14. The task scheduling method according to claim 8, wherein said ready queue storing step includes a step of storing a ready task for each priority.