JP2000047884A - Device and method for scheduling analysis, and medium where program for scheduling analysis is recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To analyze the scheduling possibility of a task set wherein periodic and aperiodic tasks are both present and to display the analysis result by scheduling periodic tasks and analyzing the scheduling possibility including aperiodic tasks according to the result. SOLUTION: A data input means 1 inputs initial information on respective tasks and information regarding analytic conditions such as a scheduling system and an analysis time. A data storage means 2 stores various input data. A scheduler 3 schedules the periodic tasks by a specified scheduling system. An initial result storage means 4 stores information obtained from the scheduling result of the periodic tasks. An analyzing means 5 analyzes the scheduling possibility including the aperiodic tasks according to the data stored in the initial result storage means 4. An analysis result storage means 6 stores the analysis result and a display means 7 displays the analysis result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to task scheduling in a real-time processing system, and more particularly, analyzes the scheduling possibility of a task set in which periodic tasks and aperiodic tasks are mixed, and displays the analysis result. And a scheduling analysis method.

[0002]

2. Description of the Related Art In a real-time processing system in which time constraints are severe, there is a constraint that each task must end a process while strictly observing a given time constraint, that is, a deadline. This is called a real-time constraint.
In addition, in this real-time processing system, a plurality of tasks are often executed in parallel, and it is important to schedule the tasks so that deadlines of the tasks are strictly observed.

A scheduling method used in such a real-time processing system is, for example, priority scheduling. In this method, a task is assigned a static priority, and the CPU having the highest priority among tasks having a processing request is used by the CPU. Other scheduling methods include a rate monotonic scheduling in which a task having a period that is periodically generated (hereinafter, referred to as a periodic task) is set to a higher priority as the cycle is shorter, a remaining time until a deadline. There is a shortest deadline priority scheduling which sets a higher priority as the value is shorter.

[0004] Using these scheduling methods,
Techniques for examining whether a given group of tasks can be scheduled to satisfy real-time constraints and verifying how to schedule them to satisfy real-time constraints are called scheduling analysis techniques. Is important in the development of real-time processing system software. Such a scheduling analysis technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-2869.
No. 58.

[0005]

However, the conventional scheduling analysis techniques only deal with periodic tasks, and deal with aperiodic tasks such as interrupt processing (hereinafter referred to as aperiodic tasks). Most did not. Also, even when dealing with aperiodic tasks, there are many methods to find the absolute limit value by repeating probabilistic analysis or exhaustive simulation assuming all cases,
The analysis was ambiguous or time-consuming.

As described above, in the conventional scheduling analysis technology, strict scheduling analysis including aperiodic tasks in the development of a real-time processing system is not performed, and real-time constraints are satisfied by giving a certain margin to the execution time. The development was proceeding as follows. Therefore, in most cases, the CPU is often in an idle state, and it is not appropriate to apply such a scheduling analysis technique in a system with severe cost constraints.

[0007] The present invention has been proposed to solve the above-mentioned problems of the prior art.
An object of the present invention is to provide a scheduling analysis device and a scheduling analysis method capable of analyzing the scheduling possibility of a task set in which a periodic task and an aperiodic task are mixed and displaying the analysis result.

[0008]

According to an aspect of the present invention, there is provided a scheduling analysis apparatus for analyzing the schedulability of a task set in which periodic tasks and aperiodic tasks are mixed. A scheduler for scheduling a periodic task, and analysis means for analyzing a possibility of scheduling including an aperiodic task based on the scheduling result.

A second aspect of the present invention is a more specific version of the first aspect of the present invention, and analyzes the scheduling possibility of a task set in which periodic tasks and aperiodic tasks are mixed. A scheduling analyzer configured to store at least information on each task, information on a scheduling scheme and analysis conditions, a scheduler for scheduling a periodic task according to a specified scheduling scheme, and a scheduling result of the periodic task. Second storage means for storing the obtained information; and analysis means for analyzing the schedulability including aperiodic tasks based on the data stored in the first and second storage means. It is characterized by the following.

The invention described in claim 6 is the first invention.
The invention described in the above is grasped from the viewpoint of the method, in a scheduling analysis method for analyzing the schedulability of a task set containing a mixture of periodic tasks and aperiodic tasks, after scheduling the periodic tasks, The method further includes an analyzing step of analyzing a possibility of scheduling including an aperiodic task based on a scheduling result.

According to the first, second, and sixth aspects of the present invention, first, a periodic task is scheduled, and how the aperiodic task is determined based on the scheduling result. By judging whether to insert it between periodic tasks at a certain execution interval,
The schedulability for all periodic and aperiodic tasks can be analyzed.

According to a third aspect of the present invention, in the scheduling analysis apparatus according to the first or second aspect, the analysis means determines that a deadline break occurs in a plurality of periodic tasks to be scheduled. The minimum execution interval candidate of the aperiodic task is obtained based on the execution end time of the periodic task that is most likely to occur, and rescheduling is performed based on the value of the minimum execution interval candidate. By repeating the process of updating the value of the minimum execution interval candidate of the aperiodic task and re-scheduling based on the updated value of the minimum execution interval candidate, the scheduling of the periodic task and the aperiodic task is performed. It is characterized in that the maximum value of the minimum execution interval candidates of the aperiodic task that can be obtained is obtained.

The invention described in claim 7 is the third invention.
In the scheduling analysis method for analyzing the schedulability of a task set in which periodic tasks and aperiodic tasks are mixed, a plurality of periodic objects to be scheduled are analyzed. Among the tasks, the minimum execution interval candidate of the aperiodic task is determined based on the execution end time of the periodic task that is most likely to cause a deadline break, and rescheduling is performed based on the value of the minimum execution interval candidate Is performed, the value of the minimum execution interval candidate of the aperiodic task is updated based on the result, and the process of re-scheduling based on the updated minimum execution interval candidate value is repeated. Minimum execution interval candidate for aperiodic tasks that enables scheduling of tasks and aperiodic tasks Is characterized in that comprises an analysis step of determining a maximum value.

According to a ninth aspect of the present invention, the invention according to the seventh aspect is viewed from the viewpoint of a medium on which a scheduling analysis program is recorded, and a periodic task and an aperiodic task are mixed. In a medium on which a scheduling analysis program for analyzing the scheduling possibility of a set is recorded, the program includes a periodic task which is most likely to cause a deadline break among a plurality of periodic tasks to be scheduled. The minimum execution interval candidate of the aperiodic task is calculated based on the execution end time of the aperiodic task, and the scheduling is performed again based on the value of the minimum execution interval candidate. Updates candidate values and allows scheduling of periodic and aperiodic tasks Is characterized in that comprises an analysis step of causing the maximum value of the minimum execution interval candidates periodic task.

According to the third, seventh, and ninth aspects of the present invention, a deadline break may occur in a plurality of periodic tasks to be scheduled. Since the highest periodic task is to be analyzed, it is not necessary to analyze all periodic tasks, and the efficiency of the scheduling analysis process is greatly improved. Further, a minimum execution interval candidate of the aperiodic task is obtained based on the execution end time of the periodic task with the highest possibility of occurrence of the deadline break, and scheduling is performed again based on the value of the minimum execution interval candidate, By repeating the process of updating the value of the minimum execution interval candidate of the aperiodic task based on the result, it is possible to determine the minimum execution interval of the aperiodic task to the optimum value while satisfying the real-time constraint. It is possible to determine the schedulability based on the result, so that the schedulability of a given task group can be calculated as an absolute value, not as an ambiguous result as in the related art.

According to a fourth aspect of the present invention, in the scheduling analyzer according to any one of the first to third aspects, a display means for displaying a result of the scheduling analysis by the analyzing means is provided. Is what you do. According to a fifth aspect of the present invention, in the scheduling analysis device according to the fourth aspect, the display means displays the analysis result by a time chart in which a color corresponding to a degree of satisfaction of a real-time constraint is displayed. It is a feature. Further, the invention according to claim 8 is:
The invention according to claim 4 is grasped from the viewpoint of a method, wherein the scheduling analysis method according to claim 6 or 7 includes a display step of displaying a scheduling analysis result by the analysis step. It is a feature.

According to the fourth, fifth, and eighth aspects of the present invention having the above configuration, the scheduling analysis result is displayed, so that it is extremely easy for the user to judge the analysis result. become.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention (hereinafter, referred to as embodiments) will be specifically described below with reference to the drawings. Each function of the embodiment described below is realized by a predetermined mechanism or software controlling a computer and peripheral devices. In this specification, “... means” corresponding to each function and each process is used. The present invention and embodiments have been described assuming virtual circuit blocks such as "... Therefore, for each block, each hardware element or software element that realizes this is one.
Does not correspond to one.

[1. Configuration] As shown in FIG. 1, the scheduling analysis display device of the present embodiment includes a data input means 1 for inputting initial information of each task, information on analysis conditions such as a scheduling method and an analysis time, and various types of input data. A data storage unit 2 for storing data (corresponding to a first storage unit in the claims), a scheduler 3 for scheduling a periodic task according to a specified scheduling method, and an initial for storing information obtained from the scheduling result of the periodic task A result storage means (corresponding to a second storage means in the claims) for analyzing the possibility of scheduling including aperiodic tasks based on the data stored in the data storage means and the initial result storage means; Analysis means 5, analysis result storage means 6 for storing an analysis result by the analysis means 5, and display of the analysis result Has the shows means 7.

The data storage means 2 has a task initial setting table 2a for storing initial information of each task and an analysis initial setting table 2b for storing information on analysis conditions.

FIG. 2 shows an example of the task initialization table 2a stored in the data storage means 2. That is, the upper part of FIG. 2 is a table in which data of the periodic tasks 1 to 4 are stored. The table includes the periodic task ID number (Periodic Task ID), the period (Period), and the execution time.
(CPU Time), Deadline Break Time
Priority is shown.

On the other hand, the lower part of FIG.
13 is a table that stores data of No. to No. 13, and indicates an aperiodic task ID number (Non-Periodic Task ID), an execution time (CPU Time), and a processing frequency relative ratio (CPU Time Ratio). Note that the processing frequency relative ratio is obtained from an allocation relative ratio of CPU occupation time between aperiodic task groups or an arrival frequency relative ratio between aperiodic task groups.

The initial result storage means 4 includes a task information table 4a for storing information obtained from the scheduling results of the periodic tasks, and a critical time calculation section 4b for calculating a critical time, which will be described later. FIG. 3 shows an example of the task information table 4a stored in the initial result storage means 4. That is, when a periodic task is actually scheduled by the scheduler 3, a task arrival time is set for one periodic task (here, task 1).
(Arrived Time), task processing start time (StartTime), task processing end time (End Time), critical time (Cri
tical Time) is shown. The critical time is obtained by the critical time calculation unit 4b according to the following equation. The deadline time is obtained from the task initial table shown in FIG.

[0024]

(Equation 1) Further, the analyzing means 5 searches for a minimum execution interval calculation unit 5a for calculating a minimum execution interval candidate for an aperiodic task and a candidate having a high possibility of breaking a deadline, and stores the candidate in the critical information table. Search unit 5b
A calculation result table 5c showing the maximum number of execution times and the minimum execution interval candidate calculated for each aperiodic task with reference to the aperiodic task ID number and the processing frequency relative ratio of the aperiodic task; And an updating unit 5d for updating data of the critical information table in preparation for a part to be analyzed.

The reason why the search unit 5b searches for a candidate having a high possibility of breaking a deadline is to minimize the number of analysis points and greatly improve the efficiency of the scheduling process. Further, the minimum execution interval calculation unit 5a is provided for explicitly calculating the schedulability including aperiodic tasks,
A maximum execution count and a minimum execution interval candidate are calculated for each aperiodic task based on the equations described below. As a result of the calculation by the minimum execution interval calculation unit 5a, when there is a minimum execution interval candidate for all aperiodic tasks, it is concluded that the task group given by the data input unit 1 is "schedulable". . In addition, as a display method by the display means 7, the analysis result of the scheduling is represented by a time chart, and a color corresponding to the degree of satisfaction of the real-time constraint can be given by referring to the critical time of the periodic task. .

[2. Operation] Hereinafter, the scheduling analysis / display processing in the present embodiment will be described with reference to the flowcharts shown in FIGS. First, analysis initial setting information and information on a task group to be subjected to scheduling analysis are input via the data input means 1 (steps 401 and 402). Next, the scheduler 3 schedules only the periodic task group according to the specified scheduling method (step 403). Next, necessary information of the scheduled periodic tasks is stored in the task information table (step 404).

Subsequently, based on the task information table indicating the obtained initial results, the analyzing means 5 determines whether or not the periodic task can be scheduled (step 405). If it is determined that "deadline break has occurred", in other words, "the periodic task cannot be scheduled", the scheduling analysis of the aperiodic task is not performed, and only the scheduling analysis result of the periodic task is analyzed. It is stored in the storage means 6 (step 40
6) The analysis result is displayed by the display means 7 (step 407), and a series of analysis / display processing ends.

On the other hand, if it is determined in step 405 that the scheduling of the periodic task is possible, the scheduling of the aperiodic task is performed according to the procedure shown in FIG. 5 described later (step 408). When the scheduling analysis of the periodic task is completed, the results of the scheduling analysis of all the task groups of the periodic task and the aperiodic task are stored in the analysis result storage means 6 (step 406), and the analysis results are displayed on the display means 7. (Step 407), a series of analysis / display processing ends.

Next, the aperiodic task scheduling analysis processing in step 408 shown in FIG. 4 will be described with reference to the flowchart shown in FIG. 5 and FIGS. As described above, the scheduling analysis processing of the aperiodic task is executed when no deadline break occurs due to the scheduling of the periodic task only.

First, the search section 5b of the analysis means 5
The scheduling result of the periodic task is obtained from the initial result storage means 4 (step 501), and the minimum critical time, which is the minimum value, is searched from the critical times indicated in the task information table. That is,
Based on the scheduling result of periodic tasks only,
A candidate for a periodic task that may break the deadline is searched for, and a critical information table storing the result is generated (step 502). The critical time in the critical information table is copied as it is from the task information table in the initial result storage means 4.

The initial value of the search start time in the critical information table is 0, and the search end time is the time at which the processing of the periodic task having the minimum critical time has ended. Therefore, the search end time is determined when the search ends. When the minimum critical time is not found as a result of the second and subsequent searches, that is, when the minimum critical time is obtained by the last task scheduled, the search end time is equal to the analysis end time.

Here, the above processing will be specifically described with reference to FIG. FIG. 6 is a time chart showing the scheduling results of the periodic tasks. Each periodic task has a critical time attached to its upper right. That is, when the result shown in FIG. 6 is obtained by the scheduling of the periodic task by the scheduler 3, the minimum critical time found in the first search is the numerical value “56” surrounded by a circle in the periodic task 3, and The end time is “42” at which the processing of the periodic task 3 having the minimum critical time ends.
0 ".

Next, step 5 in the flowchart of FIG.
In step 03, the minimum execution time calculation unit 5a of the analysis unit 5 calculates the maximum execution count of each aperiodic task by the following equation based on the minimum critical time found in the above processing and the information in the task initialization table. Desired. The aperiodic task ID number and the processing frequency relative ratio are obtained from the data of the aperiodic tasks 11 to 13 at the lower part of the task initialization table shown in FIG. In addition, the processing frequency relative ratio in this example is a relative ratio of CPU occupation time allocation between aperiodic task groups.

[0034]

(Equation 2) Subsequently, the minimum execution interval candidate for each aperiodic task is determined by the following equation based on the maximum number of executions of each aperiodic task and the search end time.

[0035]

(Equation 3) The processing in step 503 will be described using the specific example. That is, the minimum critical time is "5
6 ", from the task initialization table of FIG. 2, the aperiodic tasks 11, 12, and 13 have 3, 5, and 4 as processing frequency relative ratio values, and have 4, 8, and 6 as execution times, respectively. .

Accordingly, the maximum number of executions of each of the aperiodic tasks 11 to 13 is as follows. In addition, the calculation result is represented by a positive number after rounding off the decimal part.

[0037]

## EQU00004 ## Maximum number of executions of the aperiodic task 11 = 56.times. {3 / (3 + 5 + 4)}. Times.1 / 4 = 3.5.fwdarw.4 Maximum number of executions of the aperiodic task 12 = 56.times.5 / (3 + 5 + 4) )｝ 1/8 = 2.9 → 3 Maximum number of executions of the aperiodic task 13 = 56 × {4 / (3 + 5 + 4)} × 1/6 = 3.1 → 3 Subsequently, these calculations were performed. Thereafter, the execution times distributed to all the aperiodic tasks are summed, and it is checked whether the value does not exceed the minimum critical time. Here, “the total value exceeds the minimum critical time” means that if the maximum number of executions assigned to the aperiodic task is executed as it is, a deadline break occurs. In the present embodiment,
If the total value exceeds the minimum critical time, the adjustment is performed by reducing the number of executions of the aperiodic task having the minimum processing frequency relative ratio.

That is, in this example, when the total execution time is obtained, (4 × 4) + (8 × 3) + (6 × 3) = 58
Since it exceeds the minimum critical time “56”, the maximum execution frequency of the aperiodic task 11 having the minimum processing frequency relative ratio is corrected from 4 to 3. As a result, the total execution time is (4 × 3) + (8 × 3) + (6 × 3) = 54
Thus, even if each aperiodic task is executed three times, a deadline break does not occur, and it is concluded that scheduling until the first search end time is possible.

Subsequently, a search end time is obtained from the critical information table, and a minimum execution interval candidate for each aperiodic task is obtained based on the search end time and the maximum number of executions. As described above, since the search end time is equal to the time at which the processing of the aperiodic task having the minimum critical time ends, the first search end time in this example is “ 420 ".

With reference to these, the minimum execution interval candidates of each aperiodic task are respectively

(Equation 5) Can be calculated. At this point, the first search ends.

Subsequently, rescheduling is performed using the minimum execution interval candidate value of the aperiodic task obtained in step 503 (step 504), and the criticality of the periodic task scheduled after the first search end time is determined. How the time changes is calculated, the critical time is newly set, and the critical information table is updated (step 505).

The specific procedure for updating the critical time is as follows. First, a periodic task having the minimum critical time is searched from among the periodic tasks scheduled after the first search end time (here, “69” of the periodic task 4), and the above processing is performed. With reference to the minimum execution interval candidate of each aperiodic task obtained by the above, it is considered that each aperiodic task is inserted into the scheduling result of the periodic task. That is, 1
Since the minimum execution interval candidate of each aperiodic task obtained in the second search is “140”, how many times each aperiodic task is executed before “983” which is the end time of the second search. It is 983/1 for each execution
40 is about 7.0 times. Of these seven times, three times have already been confirmed in the first search, and it has been confirmed that a deadline break does not occur even if they are inserted into the scheduling result of the periodic task, so the total execution time of the remaining four times is obtained. And (4 × 4) + (8 × 4) + (6 × 4) = 72, which exceeds the minimum critical time “69”.

The numerical value in parentheses shown in FIG. 7 indicates the original critical time in each periodic task, and the numerical value outside the parentheses indicates the total execution time of the aperiodic task from the original critical time. This is a value obtained by subtracting the time “72”. Then, the critical information table is updated based on the result (step 505). Next, in step 506, it is determined whether or not the minimum critical time exists. If the minimum critical time does not exist, the process proceeds to step 508, in which all the results of the aperiodic task scheduling analysis are represented in FIG. The aperiodic task scheduling analysis processing is terminated, and the process proceeds to step 406 in FIG.

On the other hand, if the minimum critical time exists in step 506, it is determined whether or not the minimum critical time is minus (negative) (step 507). Since scheduling cannot be performed due to occurrence of a deadline break, the process returns to step 503 to adjust the number of executions of the aperiodic task.

As is apparent from the figure, the calculation result becomes negative for the minimum critical time “69” in the second search target even if the calculation result is not determined for all periodic tasks. By determining whether or not the deadline break is likely to occur as a result of the rescheduling, it can be analyzed.

That is, in this example, "69-72"
= −3 ″, it is clear that a deadline break may occur in the current scheduling. Therefore, the maximum number of executions of the aperiodic task 11 having the smallest processing frequency relative ratio is increased from 4 to Modify to 3. Also,
The end time of the second search is “98” as shown in FIG.
3 ".

Referring to these, the minimum execution interval candidates of each aperiodic task are respectively

(Equation 6) Becomes That is, the minimum execution interval candidates of the aperiodic task 11 are “140” to “16” of the result of the first search.
4 ". At this point, the second search is completed.

Then, in step 504, rescheduling is performed using the newly obtained value of the minimum execution interval candidate of the aperiodic task, and the processing of steps 505 to 508 is repeated, and the processing of each aperiodic task is repeated. The minimum execution interval candidate is updated according to the calculation result. Thus, the maximum value of the minimum execution interval of each aperiodic task that can be scheduled can be calculated.

On the other hand, if there is no negative critical time in step 507, all of the scheduled periodic tasks and aperiodic tasks are within the deadline, so the process proceeds to step 508.
All the results of the aperiodic task scheduling analysis are stored in the analysis result storage means 6 of FIG. 1, and the aperiodic task scheduling analysis processing ends, and the process proceeds to step 406 of FIG.

The display of the analysis result in step 407 in FIG. 4 is performed by the display means 7 in FIG.
For example, as shown in FIG. 8, the image is displayed in a time chart with color discrimination. In this figure, the darker the part of the chart is, the higher the risk of deadline break is expressed.

[3. Effect] As described above, according to the scheduling analysis device of the present embodiment, the scheduling analysis that handles not only periodic tasks but also aperiodic tasks satisfies the real-time constraint on the minimum execution interval of aperiodic tasks. Since this can be realized by determining the optimum value, the scheduling possibility of a given task group can be calculated as an absolute value, not as a vague result as in the related art. Further, since the calculation means can be easily realized, the scheduling analysis in the development of the real-time processing system can be performed at low cost. Further, since the result of the scheduling analysis can be displayed using a time chart colored in accordance with the degree of satisfaction of the real-time constraint, it is very easy to determine the result of the scheduling analysis.

[0052]

As described above, according to the present invention,
It is possible to provide a scheduling analysis device and a scheduling analysis method capable of analyzing the scheduling possibility of a task set in which a periodic task and an aperiodic task are mixed and displaying the analysis result.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a scheduling analyzer according to the present invention.

FIG. 2 is a diagram illustrating an example of a task initialization table.

FIG. 3 is a diagram showing an example of a task information table representing scheduling result information of a periodic task.

FIG. 4 is a flowchart showing a flow of a process in the scheduling analyzer.

FIG. 5 is a flowchart showing a flow of a scheduling analysis process of an aperiodic task group;

FIG. 6 is a diagram showing an example of a time chart display showing a scheduling result of a periodic task.

FIG. 7 is a diagram showing an example of a time chart display showing a scheduling result of a periodic task after updating a critical time.

FIG. 8 is a diagram showing an example of a time chart display showing a scheduling analysis result including a periodic task and an aperiodic task;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Data input means 2 ... Data storage means 2a ... Task initial setting table 2b ... Analysis initial setting table 3 ... Scheduler 4 ... Initial result storage means 4a ... Task information table 4b ... Critical time calculation part 5 ... Analysis means 5a ... Minimum execution Interval calculation unit 5b Search unit 5c Calculation result table 5d Update unit 6 Analysis result storage unit 7 Display unit

Claims (9)

[Claims] 1. A scheduling analyzer for analyzing the schedulability of a task set in which a periodic task and an aperiodic task are mixed, a scheduler for scheduling a periodic task,
Analyzing means for analyzing the possibility of scheduling including non-periodic tasks based on the scheduling result. 2. A scheduling analysis device for analyzing the schedulability of a task set in which periodic tasks and aperiodic tasks coexist. A first storage for storing at least information relating to each task, information relating to a scheduling method and analysis conditions. Means, a scheduler for scheduling a periodic task according to a specified scheduling method, a second storage means for storing information obtained from a scheduling result of the periodic task, and a scheduler for storing information obtained from the first and second storage means. Analyzing means for analyzing the possibility of scheduling including aperiodic tasks based on the obtained data. 3. The non-periodic task based on the execution end time of the most probable occurrence of a deadline break among a plurality of periodic tasks to be scheduled. The minimum execution interval candidate is obtained, the scheduling is performed again based on the value of the minimum execution interval candidate, the value of the minimum execution interval candidate of the aperiodic task is updated based on the result, and the updated minimum execution interval is further updated. By repeating the process of rescheduling based on the value of the candidate, the maximum value of the minimum execution interval candidate of the aperiodic task that enables the scheduling of the periodic task and the aperiodic task is obtained. The scheduling analysis device according to claim 1. 4. The scheduling analysis apparatus according to claim 1, further comprising a display unit for displaying a result of the scheduling analysis by the analysis unit. 5. The scheduling analysis device according to claim 4, wherein the display means displays the analysis result in a time chart in which a color corresponding to the degree of satisfaction of the real-time constraint is applied. 6. A scheduling analysis method for analyzing the schedulability of a task set in which a periodic task and an aperiodic task coexist. In the scheduling analysis method, after a periodic task is scheduled, an aperiodic task is determined based on the scheduling result. A scheduling analysis method including an analysis step of analyzing the schedulability that is included. 7. A scheduling analysis method for analyzing the schedulability of a task set in which periodic tasks and aperiodic tasks coexist. A deadline break occurs in a plurality of periodic tasks to be scheduled. The minimum execution interval candidate of the non-periodic task is obtained based on the execution end time of the periodic task with the highest possibility, the scheduling is performed again based on the value of the minimum execution interval candidate, and the non-periodic The periodic task and the aperiodic task can be scheduled by repeating the process of updating the value of the minimum execution interval candidate of the periodic task and further performing the scheduling again based on the updated value of the minimum execution interval candidate. Analysis step for finding the maximum value of the minimum execution interval candidates of the aperiodic task Scheduling analysis method characterized by and. 8. The scheduling analysis method according to claim 6, further comprising a display step of displaying a result of the scheduling analysis by the analysis step. 9. A medium on which a scheduling analysis program for analyzing a scheduling possibility of a task set in which a periodic task and an aperiodic task are mixed is recorded, wherein the program comprises a plurality of periodic tasks to be scheduled. In the meantime, the minimum execution interval candidate of the aperiodic task is determined based on the execution end time of the periodic task with the highest possibility of occurrence of the deadline break, and the scheduling is performed again based on the value of the minimum execution interval candidate. The maximum value of the minimum execution interval candidate of the aperiodic task that allows the periodic task and the aperiodic task to be scheduled based on the result. Recording a scheduling analysis program characterized by including an analysis step for obtaining Media.