JPH03177932A - Periodical task control system - Google Patents

Abstract

PURPOSE:To start a periodical task with the accurate periodicity by setting the remaining time to the set periodical time of the periodical task when the execution of this task is started. CONSTITUTION:A task control block TCB includes a remaining time control area R2 which controls the remaining time until the next task is started. The execution start timing of a periodical task TA1 is decided by the remaining time stored in the area R2. This remaining time is set to the set periodical time of the task TA1 when starting the execution of the task TA1. Thus the periodical start of the task TA1 is secured even when the interruption state of the task TA1 caused by execution of a task TA2 having the higher priority than the task TA1 is kept within a waiting time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a periodic task management method in a multitasking system that manages a plurality of tasks activated at regular intervals.

[Prior Art] Conventionally, in a multitasking system, when there is a fixed-period task that is activated at regular intervals and a task that has a higher priority than the fixed-period task, processing of the fixed-period task is executed. If an interrupt request occurs from a high-priority task during the interval, the processing of the currently executing periodic task is interrupted, the high-priority task is executed, and the interrupted routine is resumed after the execution of this task is completed. Processing of the periodic task is restarted, and after the periodic task has finished processing, the periodic task is configured to be activated again after a waiting state for a certain period of time.

[Problems to be Solved by the Invention] However, in the conventional multitasking system described above, after the processing of the periodic task is completed, the periodic task is activated again after a certain waiting state. )) When there is no interrupt from a task with a higher priority while the periodic task shown in ()) is being executed, the task is executed after a certain period of time has passed from the end of the periodic task processing, as shown in section T1. , the process of the periodic task will be executed again, and the periodic period can be secured, but the period T
2 and T3, during the execution of a periodic task, FIG.
When the execution of a periodic task is interrupted due to an interrupt from a task with a high priority as shown in a), the start of execution of the next periodic task will be delayed by the interruption time, that is, the processing time of the task with a high priority. However, there has been an unresolved problem that the intervals at which periodic tasks are activated are not necessarily constant, reducing the operability and reliability of the system.

In addition, if the processing of a fixed-period task is delayed beyond the fixed period due to a long interruption by a task with a higher priority or several interruption processes, the number of fixed-period tasks and the number of task activations may not match. There was also an unresolved issue that the operability and reliability of the system deteriorated.

Therefore, the present invention has been made by focusing on the unresolved problems of the above-mentioned conventional example, and provides a periodic task management method that can ensure periodic activation of periodic tasks, and also It is an object of the present invention to provide a periodic task management method to improve the operability and reliability of the system by preventing discrepancies between the number of regular periods and the number of task activations due to a delay in activation timing that exceeds .

[Means to solve the problem]

In order to achieve the above object, the periodic task management method according to claim (1) includes a periodic task that is started at a preset fixed period, and a task that has a higher priority than the periodic task. In a multitasking system with
At least a remaining time management area and a set cycle time storage area are formed in the task control block of the fixed periodic task, and the remaining time in the remaining time management area is frozen at a predetermined period by a subtraction means, so that the remaining time becomes zero. The present invention is characterized in that the set cycle time storage means stores the set cycle time in the set time storage area in the remaining time management area, and the task activation means starts processing the fixed cycle task.

The fixed-period task management method according to claim (2) is applicable to a multi-task system having a fixed-period task that is activated at a preset fixed period, and a task that has a higher priority than the fixed-period task. , forming at least a remaining time management area, a set cycle time storage area, and a startup delay count storage area in the task control block of the fixed periodic task, and subtracting the remaining time in the remaining time management area at a predetermined period by a subtracting means; When the remaining time becomes zero, the set cycle time storage means stores the set cycle time in the set time storage area in the remaining time management area, and the task status determination means determines whether or not the fixed cycle task is in a waiting state. If it is in a waiting state, the task activation means starts processing the fixed-period task, and if it is not in a waiting state, it increments the number of startup delays in the startup delay number storage area, and when the processing of the fixed-period task is finished. Then, it is determined whether or not the number of startup delays is zero, and if it is zero, the fixed periodic task is placed in a waiting state, and if it is not zero, the number of startup delays is decremented, and then the task starting means executes the fixed periodic task. The feature is that the process is re-executed.

[Operation] In the periodic task management method according to claim (1),
When a fixed-period task is started, the fixed-period time is stored as the remaining time in the remaining time storage area of the task control block, the remaining time in this remaining time storage area is subtracted at a fixed period, and when this becomes zero, the fixed-period time is stored as the remaining time. Since task processing is started, if the interruption state due to the execution of a task with a higher priority during execution of a periodic task is within the waiting time of the periodic task, it is possible to ensure the periodic activation of the periodic task. can.

Further, in the fixed-period task management method according to claim (2), when the fixed-period task is activated, it is determined whether the fixed-period task is in a waiting state, and when the fixed-period task is in the waiting state, the fixed-period task processing is executed. However, when it is not in the waiting state, that is, when it is in the processing execution state or the suspended state, it is determined that the processing of the periodic task is delayed, and the number of startup delays in the startup delay number storage area of the task control block is incremented, When the processing of a fixed-period task is completed, the number of startup delays is determined. If this is zero, the fixed-period task is placed in a waiting state, and if it is other than zero, the number of startup delays is decremented and the fixed-period task is immediately processed. By re-executing the task, the activation delay time of the fixed-period task is shortened, and the number of fixed-period tasks and the number of task activations are matched.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a task configuration diagram showing a first embodiment of the present invention.

A periodic task has a waiting state section 2 in the eternal loop 1, and when it is in this waiting state section 2, that is, when it is in the waiting state, the task control program TCB of the task is linked to the periodic task queue. When a fixed period has elapsed, the waiting state section 2 shifts to the processing section 3 and enters the processing execution state.

As shown in FIG. 2, the task control block TCB includes a pointer storage area RI for storing the pointer of the next waiting task, and a remaining time t until starting the next task.
It has a remaining time management area R2 for managing R, a set cycle time storage area R3 for storing the set cycle time t of its own task, and a start delay count storage area R4 for storing the number of start delays.

In the queue, the task control blocks TCB of each task are linked in descending order of the remaining time until the next activation, as shown in FIG. It is stored in C1.

Then, the periodic interrupt processing (for example, 10 m
When the interrupt processing (interrupt processing every 5ec) is executed, the count contents of the fixed-cycle timer down counter C are counted down in step (2), and then the process proceeds to step (2), where the count value of the counter C1 becomes zero and the time amplifier If the time has not expired, the interrupt processing f is immediately terminated, and if the time has expired, the process moves to step 2 and stores the set cycle time in the remaining time management area R2 of the task control block TCB of the corresponding task. After storing the set cycle time stored in the area R1, the task is linked to the queue again, and then the process moves to step (2) to transition the fixed cycle task from the wait state to the execution state.

When the processing of the task is completed, the execution state transitions to the wait state.

Next, the operation of the above embodiment will be explained. Now, Figure 5(b)
As shown at time t. Periodic task TA in waiting state
It is assumed that the task control block TCB of , is linked to the head of the queue, and the remaining times t and l of the remaining time management area R2 are stored in the fixed-cycle timer down counter CI. In this state, when the periodic interrupt process shown in FIG. Each time a process is executed, the counter C1 is counted down, and when the counter C9 times out at time t1, the process moves from step ■ to step ■, and the remaining time management area R2 of the task control call block TCB is counted down.
The set cycle time of the task is stored in , and this task control block TCB is re-linked to the position corresponding to the remaining time 1R in the queue, and then the process moves to step (2) where the processing of the fixed cycle task is started in the fifth As shown in (in the figure), execution starts and transitions to the execution state.

In the execution state of this task, if no interruption occurs due to the execution of a task with a higher priority, as shown in interval TI, the execution state is continued and when the processing is completed, the execution state is returned to the wait state. . During this time, the remaining time management area R2 of the task control block TCB of each task
The remaining times t and R are sequentially decreased at the start timing of the periodic interrupt process shown in FIG.

Thereafter, other tasks are activated in order of decreasing remaining time, and when task TA is linked to the head of the queue, the remaining time tR in the remaining time management area R1 of the task control block TCB changes at regular intervals. This is set in a timer down counter C0, which is counted down every time the periodic interrupt processing shown in FIG. When an interrupt by a task TA with a high priority occurs, the periodic task TA transits from the execution state to the suspended state, and task TA is executed instead, and at time t4 task TA
When the processing of , , is completed, the suspended task TA returns to the execution state, and thereafter, when the processing of task TA is completed at time L5, the task TA returns to the waiting state.

In this way, the execution start timing of the periodic task TA is determined by the remaining time management area R7! formed in the task control block TCB! This remaining time tI+ is determined by the stored remaining time tR, and this remaining time tI+ is determined by the periodic task TA,
At the start of execution of periodic task TA, set periodic time Ls
Therefore, the activation timing of the periodic task always matches the set period time. Therefore, the time from when the periodic task T A + starts processing until it ends is equal to the set period time. When it is within 3, constant periodicity can always be ensured.

Next, a second embodiment of the present invention will be described with reference to FIGS. 6 to 8.

In addition to ensuring regular periodicity as in the first embodiment, this second embodiment also ensures that when the time from the start to the end of processing of a periodic task exceeds the set period time, the number of inter-periodic tasks and the number of task activations are The aim is to match the

That is, as shown in FIG. 6, in the periodic interrupt processing, a step (2) for determining whether or not a periodic task is in a waiting state is added between step (2) and step (2) in FIG.
If the result of this determination is that the task is in the waiting state, the process moves to step (2) to start executing the periodic task process, and if the periodic task is in the running or suspended state, the process moves to step (2) and the process is started in the task control block TCB. , is configured to end the interrupt processing after counting up the number of startup delays N in the delay number storage area R6, and when the periodic task TA finishes processing and transitions to the waiting state, the seventh The wait state process shown in the figure is activated.

In this wait state process, in step (3), it is determined whether the number of startup delays N in the startup delay number storage area R4 in the task control block TCB is zero, and if N=O, the periodic task TA is activated. If it is determined that there is no timing delay, the process moves to step @, and the periodic task TA is placed in a waiting state. If N>0, the process moves to step 2, and the start delay count in the start delay count storage area R4 is changed. Count down the number of times N and then step [phase]
Then, the periodic task TA is restarted and put into a re-execution state.

Next, the operation of the second embodiment will be explained with reference to the timing chart of FIG.

Now, at time t0, it is assumed that the number of startup delays N in the startup delay number storage area R4 of the task control block TCH of the periodic task T A + is zero, and the task control block TCH of the periodic task T A + is at the head of the queue in a waiting state. When the periodic interrupt processing shown in FIG. 6 is executed in this state, as described above, the waiting state continues until the periodic timer down counter C times up, and when the counter C1 times up at time t1, The set periodic time t of the periodic task TA1 is set as the remaining time tR in the remaining time management area R2 of the task control block TCB, and the periodic task TA1 is relinked to the queue (step ■), and then the periodic task TA is placed in a waiting state. Therefore, the periodic task TA is transitioned to the execution state (step 2).

At this time, the number of startup delays N in the startup delay number storage area R4 continues to be zero.

After that, when the processing of the periodic task TA is finished at time t2, the waiting state process shown in FIG. Since N=0, the periodic task TA is transited to the waiting state.

Thereafter, at time t3, the periodic task TA transits to the execution state again, and at time L4, the periodic task TA becomes suspended due to an interrupt from a task with a higher priority, and this suspended state causes the next periodic task to start. When the interrupt processing continues beyond time t, the periodic interrupt process shown in FIG. Since the periodic task TA is in a suspended state, the process moves to step (3), counts up the number of startup delays N to "1", and then ends the interrupt process.

Therefore, at time L6, the processing of the high priority task TA2 is completed and the periodic task TA returns to the execution state.
Next, when the processing of the periodic task TAI is completed at the time point, when the waiting state processing shown in FIG.・Count down the number of startup delays N and turn O".

Then, proceed to step @ and execute the periodic task TA,
Put it into running state again.

Thereafter, at time 1a, the number of startup delays N is incremented to "1" by the periodic interrupt processing again, so at time t9 when the processing of periodic task TA is completed, periodic task TAI is again in the execution state. At the time too when this processing is completed, the number of startup delays N has not been counted up due to the periodic interrupt processing, so the periodic task T is transferred from step ■ to step @ in the waiting state processing of FIG.
A.

is transitioned to the waiting state.

As described above, according to the second embodiment, when the time from the start to the end of the periodic task processing exceeds the set period time, the processing is restarted at the point when the periodic task processing is completed. Therefore, even if a task with a higher priority has a longer execution time than a fixed-period task or a task with a higher priority has been executed more often than a fixed-period task, the number of fixed-period tasks and the number of task starts will match. It can be adjusted as follows.

〔Effect of the invention〕

As explained above, according to the fixed-period task management method according to claim (1), when the start-up management of a fixed-period task is started, the remaining time is determined by the set period of the fixed-period task. Since the startup timing of periodic tasks does not deviate from the set periodic time interval, it can be started with accurate periodicity, improving the operability of the multitasking system. The effect of improving reliability and reliability can be obtained.

Further, according to the periodic task management method according to claim (2), in addition to the above effects, the time from the start to the end of processing of a periodic task is longer than the set periodic time for that task. Since the process is started again when the process is completed if the process is long, it is possible to correct the difference between the number of regular cycles and the number of task activations, thereby resolving the discrepancy between the two.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a periodic task showing a first embodiment of the present invention, FIG. 2 is a configuration diagram showing a task control block of a periodic task, FIG. 3 is a state diagram showing a queue, and FIG. 4 is a flowchart showing an unusual example of fixed period interrupt processing, FIG. 5 is a timing chart for explaining the operation of the first embodiment, and FIGS. FIG. 8 is a timing chart for explaining the operation of the second embodiment, and FIG. 9 is a timing chart for explaining the operation of the conventional example. In the figure, 1 is an eternal loop, 2 is a waiting state part, 3 is a processing part,
TA is a periodic task, TA2 is a high priority task, T
CB is a task control block, R1 is a pointer area, R2 is a remaining time management area, R3 is a setting cycle time storage area, and R4 is a startup delay count storage area. Broom diagram 7

Claims (2)

[Claims] (1) In a multitasking system having a fixed cycle task that is started at a preset fixed cycle and a task that has a higher priority than the fixed cycle task, at least the remaining time is managed in the task control block of the fixed cycle task. A subtracting means subtracts the remaining time in the remaining time management area at a predetermined period, and when the remaining time becomes zero, the setting period time storage area is stored in the setting period storage area. A periodic task management method, characterized in that a set periodic time is stored in a remaining time management area, and processing of the periodic task is started by a task starting means. (2) In a multitasking system having a fixed cycle task that is activated at a preset fixed cycle and a task that has a higher priority than the fixed cycle task, the task control block of the fixed cycle task at least manages the remaining time. forming a storage area, a setting cycle time storage area, and a startup delay count storage area, subtracting the remaining time in the remaining time management area at a predetermined period by a subtracting means, and when the remaining time becomes zero, setting cycle time storage means; The set cycle time of the set time storage area is stored in the remaining time management area, and the task state determining means determines whether the periodic task is in a waiting state, and if it is in the waiting state, the task activation means Starts processing of a fixed-period task, increments the number of startup delays in the startup delay number storage area when it is not in a waiting state, and checks whether the number of startup delays is zero when processing of the fixed-period task is completed. The periodic task is characterized in that the periodic periodic task is determined, and when the periodic periodic task is zero, the periodic periodic task is placed in a waiting state, and when it is not zero, the periodic periodic task is made to re-execute the process of the periodic task after decrementing the number of startup delays concerned and then re-executed by the task starting means. Management method.