JPH06149599A - Computer system - Google Patents

Abstract

PURPOSE:To provide the computer system which can schedule tasks of all periods by providing scheduling in which case conventional periodical scheduling cannot be scheduled and there are tasks having execution periods shorter than a minimum reference period. CONSTITUTION:This computer system consists of a scheduling mode selecting part 26 and a time slot assigning part 11 in addition to the system constituting the conventional scheduling system. The scheduling mode selecting part 26 changes the scheduling mode from the periodical scheduling mode to the priority when there are tasks existed that are execution periods shorter than the minimum reference period which becomes the reference period at the time of periodically checking the activation of tasks by a scheduling execution part 13 in the activation requesting tasks. The time slot assigning part 11 generates table information 23 of scheduling in accordance with the selected scheduling mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system in which a plurality of tasks are executed, and more particularly to a computer system having a function of managing and scheduling a plurality of tasks having a unique execution cycle and execution time. is there.

[0002]

2. Description of the Related Art FIG. 15 is a block diagram of a part related to scheduling of a computer system provided in, for example, "Mitsubishi Electric Integrated Control System MELTAS JP-EI S / W Construction Manual" (published in May 1991, 1st edition). Is.

First, the concept of periodic scheduling will be described with reference to FIG. The minimum reference cycle in the figure is the reference cycle when the activation of tasks is checked periodically, and is the minimum cycle for scheduling application tasks 1 to L (L is the number of tasks) that are executed periodically. is there. A time slot is a time unit obtained by dividing the above-mentioned minimum reference period by a predetermined value N (determined by the user according to the system), and the scheduler selects the execution tasks 1 to L for each time slot time. The execution level is a set of a plurality of tasks obtained by classifying the execution tasks 1 to L for each cycle, and the execution levels 1 to N are assigned to the time slots 1 to N.
M is interrupted (allocation method will be described later). When executing the scheduling, the scheduler preferentially executes a task waiting for activation of the execution level assigned to the time slot in a certain time slot (a method of selecting the execution level will be described later).

In the example of FIG. 16, execution level 1 is assigned to time slot 1 and time slot 2, execution level 2 is assigned to time slot 3, and execution level M is assigned to time slot (N-1). It is a spare time slot (α) for the system time required for each time slot as execution time selection time and time slot calculation time, and execution level 1 is assigned. Run level 1
Two tasks, task 1 and task 2, belong to task 2, task 3 to task level 2, task L to task level M. At the time of scheduling, a time slot calculation unit described later calculates a time slot value from the value of the timer. In time slot 1, execution level 1 is selected and task 1 of execution level 1 is being executed. Also in the time slot 2, the execution level 1 is selected and the task 1 is executed in the same manner. The execution level 2 is selected in the time slot 3, and the belonging task 3 of the execution level 2 is executed. Since the time slot N is a spare time slot, an unexecuted task is executed within the minimum reference period. The execution level selection as described above is repeated every minimum reference period.

In FIG. 15, reference numeral 11 includes information of time slots to which tasks are classified into execution levels from task information 12 including a unique execution cycle and execution time for each task provided by the user, and execution levels are assigned. A time slot allocation unit that generates table information (change value) 23 and stores the table information 23 in the time slot corresponding task information table 21, and as shown in FIG.
Execution cycle discriminating means 11a for discriminating the execution cycle of each task from the task information 12, classifying means 11b for discriminating each task from an execution level having a short execution cycle to a long level based on the discrimination result, and the above-mentioned for each time slot. The time slot allocating means 11c for allocating the execution level is included. On the other hand, 13 in FIG. 15 is triggered by the time slot change interrupt 17 from the time slot calculation unit 16 which will be described later, and the time slot corresponding task information table 2
A scheduling execution unit for selecting and executing an execution task based on table information (current value) 22 from 1 and a time slot value (current value) 20 from a time slot information storage unit 18 described later, and 16 is an operating system The function software (hereinafter abbreviated as S / W) is activated by a fixed-cycle interrupt 15 from a timer 14, calculates a time slot value (change value) 19 from the current time, and stores it in a time slot information storage unit 18. A time slot calculation unit that writes the value, interrupts the current task execution by causing the scheduling execution unit 13 to change the time slot information, interrupts the current task execution, and causes the scheduling execution unit 13 to select the activation task. , The calculated time slot value is also stored internally. Tsu capital value is incremented as the previous value of the time slot at the time of the calculation of the next time. 24 is
The activation request task 25 passed from the user as the task information 12 is stored in the time slot correspondence task information table 21.
It is an activated task queuing unit that queues in a queue (waiting queue) created by a task management table described later.

FIG. 18 is a detailed view of each table included in the time slot corresponding task information table 21 of FIG. 211 is a time slot management table that stores information on execution levels 1 to M assigned to each of the time slots 1 to N, and 212a to 212c store queuing states of tasks of each execution level assigned to each time slot value. Level management tables 213a1-213a
Reference numerals n, 213b1, 213c1, and 213c2 are task management tables for generating the above-mentioned queue. The time slot management table 211 stores pointers a to c indicating the addresses of the level management tables 212a to 212c corresponding to the execution levels 1 to M assigned to the time slots 1 to N, respectively. The time slot N is a spare time slot (α) for system time, and the execution level 1 is assigned to preferentially execute a task having a small execution level. Task management tables 213a1-21
3c2 is a pointer that points to the address of the next task management table (however, the pointers of the task management tables 213an, 213b1, 213c2 at the end of the queue are NULL pointers indicating that there is no subsequent table)
And the information of the startup task is stored. Further, the level management tables 212a to 212c store a pointer pointing to the address of the task management table at the head of the queue and a pointer pointing to the address of the task management table at the tail of each execution level. For example, level 1
By storing the pointer a1 indicating the address of the first task management table 213a1 of the queuing task belonging to the execution level 1 and the pointer an indicating the address of the last task management table 213an in the level management table 212a for , Provides information that the tasks shown in these task management tables 213a1 to 213an are waiting tasks.

Next, the operation will be described. First, the means for assigning the execution level to the time slot management table 211 by the time slot assigning section 11 will be described with reference to the flow charts of FIGS. Prior to the allocation, based on the input task information 12, the execution cycle discriminating means 11a and the classifying means 11b determine M start-up tasks for each execution cycle (a number determined by the number of executed tasks and system capability by the user). ) Is performed (ST191). Next, the time slot allocation means 11
By c, the following processing is repeated for execution levels 1 to M (ST192). First, for the execution level 1, the total execution time in the minimum reference cycle unit is obtained by multiplying the sum of all the task execution times belonging to the execution level 1 by the ratio of the execution cycle of the execution level 1 to the minimum reference cycle. (ST193). For example, when the execution cycle of a task of execution level 1 is 100 ms, the total execution time of tasks of execution level 1 is 40 ms, and the minimum reference cycle is 50 ms, 40
× (50/100) = 20 ms is the required value. That is, the execution level 1 requires an execution time of 20 ms within the minimum reference period. The result is divided by the time slot time, the number after the decimal point is rounded up, and the number of time slots required for execution level 1 within the minimum reference period is obtained (ST194).
In the above example, when the time slot time is 10 ms, 2
0/10 = 2, so two time slots are needed. The above processing is similarly repeated from execution level 2 to M (ST195), and the number of time slots required for each execution level is obtained. Next, the number of time slots required for the system execution time required to execute the task within the minimum reference period is calculated by dividing the system execution time by the time slot time and rounding up to the decimal point (ST196). Above,
Each execution level and the number of time slots required by the system can be calculated. However, if the total exceeds the number N of time slots of the minimum reference cycle, the maximum execution load will be exceeded and scheduling will not be possible. When the number N of time slots in the reference cycle is compared (ST197) and the total is larger than the number N of time slots, pointers to the level management table are set to the time slot management table 2 by the required number of time slots in order from execution level 1.
11 and the remaining level is ignored when the time slot management table 211 is satisfied (S
T199). If the total is smaller than the number of time slots N, the time slots are stored in the time slot management table 211 in order from the execution level 1 (ST198). This completes the allocation of execution levels to time slots.

Next, a scheduling method using the time slot management table 211 by the scheduling execution unit 13 will be described with reference to the flowchart of FIG. S
In response to the fixed-cycle timer interrupt 15 from the / W timer 14, the time slot calculation unit 16 causes the time slot value 19
Is calculated, the value is stored in the time slot information storage unit 18, and the time slot change interrupt 17 is output to the scheduling execution unit 13. Scheduling execution unit 13
In response to this change interruption 17, the operation starts. The current time slot value 20 is set to the time slot information storage unit 1
18 is acquired (ST211), and the execution level assigned to the acquired time slot value is acquired from the execution levels 1 to M of the time slot management table 211 of FIG. 18 (ST212). The existence of tasks (waiting tasks) queued at the execution level is checked using the level management tables 212a to 212c (ST21.
3) If it is queued, the leading task is executed (ST214). For example, when the time slot value from the time slot information storage unit 18 is 1, the scheduling execution unit 13 causes the time slot management table 211 to indicate the level management table 212a indicated by the pointer a.
Is checked and the task of the head task management table 213a1 indicated by the pointer a1 is executed. If it is not queued in, the execution level is incremented (S
(T216), the queuing state check is repeated for the level management table for the next execution level. Since the execution level is checked cyclically as shown in FIG. 22 starting from the execution level assigned to the current time slot, the execution level is returned to 1 when the execution level exceeds M (ST217, ST218). When all execution levels have been cycled through the above checks (ST219), it is determined that there is no execution task for all execution levels (ST220). Whether or not there is an execution task, the time slot change interrupt 17 is waited for (ST215), the process returns to the acquisition of the next time slot value, and the above operation is repeated.

[0009]

Since the conventional computer system is configured as described above, in the time slot allocation method shown in FIGS. 19 and 20, periodical scheduling reduces the load on the processor. Although it is possible to make them even, the periodical check of task activation is executed in the minimum reference period, so periodic scheduling below the minimum reference period is impossible. Therefore, for a task having an execution cycle shorter than the minimum reference cycle, the user has to determine the execution cycle so that such a task does not exist. Further, since only the execution request task designated by the user in advance, that is, the task assigned to the time slot management table, can be executed, it is impossible to perform the aperiodic interrupt processing such as error processing together with the periodic task. There was a problem.

The present invention has been made to solve the above problems, and provides scheduling in the case where there is a task whose execution period is less than the minimum reference period, in addition to the conventional periodic scheduling. The purpose of the present invention is to obtain a computer system that enables scheduling of tasks with a period of. Also, with periodic tasks,
It is an object of the present invention to obtain a computer system capable of non-periodically occurring interrupt processing such as error processing.

[0011]

A computer system according to a first invention of the present invention is a computer system having a function of managing and scheduling a plurality of tasks having a unique execution cycle and execution time. Execution cycle determination means for determining the execution cycle of the task, a classification means for classifying each task into a level from a short execution level to a long execution level based on the determination result of the execution cycle determination means, and a task start-up periodically Time slot allocation means for allocating the above execution level to a time slot, which is a time unit obtained by dividing the minimum reference cycle, which is the reference when checking, by the predetermined value, and the execution cycle of the execution level in which the tasks of the minimum execution cycle are classified. Comparing means for determining whether or not is shorter than the above-mentioned minimum reference period, and based on the result of this comparison, preset in each time slot A scheduling mode switching means for switching the periodic scheduling mode to assign each run level according to the periodicity that is, with all of the priority scheduling mode assigning an execution level minimum execution cycle of the task is classified into time slots,
And a scheduling execution means for executing task scheduling from the execution level assigned to the time slot corresponding to the current time, and the execution cycle of the execution level in which the tasks of the minimum execution cycle are classified by the comparison means is smaller than the minimum reference cycle. When it is determined that the time is short, the scheduling mode switching means switches from the normal periodic scheduling mode to the priority scheduling mode, and based on this, the time slot allocating means classifies the tasks of the minimum execution period into all the time slots. The execution level is assigned.

Further, the computer system according to the second aspect of the present invention determines the execution cycle of each task from the execution level with the short execution cycle based on the execution cycle judgment means for judging the execution cycle of each task and the judgment result of this execution cycle judgment means. A classifying unit that divides levels into long execution levels, and a time slot allocation that assigns the above execution level to a time slot that is a time unit that is the minimum reference cycle that is the standard when checking the activation of tasks periodically divided by a predetermined value. And scheduling execution means for executing task scheduling from the execution level assigned to the time slot corresponding to the current time, and notifies the scheduling execution means of the occurrence of an aperiodic event such as an error occurrence by an interrupt. The interrupt generating means and the interrupt processing means for performing the processing when the above interrupt occurs The scheduling execution means, when the interrupt occurs, when the interrupt processing has a higher priority than the periodic task based on the priority of the periodic task and the interrupt processing determined in advance, that is, the priority, The execution is temporarily suspended so that the interrupt processing means executes the interrupt processing.

On the other hand, the computer system according to the third aspect of the present invention, like the first aspect of the present invention, determines the execution period of each task by an execution period determination means for determining the execution period of each task and the determination result of the execution period determination means. A classifying unit that divides the execution level from a short execution level to a long execution level, and a time slot that is a time unit that is a time unit obtained by dividing a minimum reference cycle that is a reference when periodically checking the activation of a task by the above A time slot assigning means for assigning an execution level, a comparing means for determining whether or not the execution cycle of the execution level into which the task of the minimum execution cycle is classified is shorter than the minimum reference cycle, and each time slot based on the comparison result. A periodic scheduling mode in which each execution level is assigned according to a preset cycle, and a minimum execution cycle for all time slots. The hardware includes a scheduling mode switching means for switching a priority scheduling mode for allocating an execution level into which tasks are classified, and a scheduling execution means for executing task scheduling from the execution level allocated to the time slot corresponding to the current time. An interrupt generator for generating an interrupt to the scheduling execution means at each time slot time based on the clock from the timer;
A counter that counts each time slot value based on the clock from the hardware timer and the time slot value is set by the counter, and the time slot value at the current time is set by the scheduling execution means each time an interrupt is generated from the interrupt generator. The scheduling mode switching means includes a register to be read, and when the comparison means determines that the execution cycle of the execution level into which the task of the minimum execution cycle is classified is shorter than the minimum reference cycle, the scheduling mode switching means operates in the normal periodic scheduling mode. To the priority scheduling mode, and based on this, the time slot allocating means allocates the execution level in which the tasks of the minimum execution cycle are classified to all the time slots.

[0014]

In the computer system according to the first aspect of the present invention, before the time slot allocating means executes the execution level time slot allocation, the execution cycle determining means, the classifying means and the comparing means perform the execution cycles less than the minimum reference cycle. Check the existence of the task. If it exists,
The scheduling mode switching means switches from the normal periodic scheduling mode to the priority scheduling mode. When the time slot allocating means recognizes that the scheduling mode is the priority scheduling mode, it allocates the execution level of the minimum execution cycle to all the time slots. The scheduling execution means executes tasks in all time slots in order from the execution level of the allocated minimum execution cycle. By assigning the execution level with the minimum execution cycle to all time slots, tasks are always checked in order from the execution level with the minimum execution cycle. As a result, the execution level with the minimum execution cycle is given the highest priority and Priority scheduling that checks task activation in slots is realized.

Further, in the computer system according to the second aspect of the present invention, the scheduling executing means checks whether or not there is an interrupt from the interrupt generating means, and if there is no interrupt, the normal periodic scheduling is performed. If there is an interrupt, based on the priority of the periodic task and the interrupt processing, if the priority of the interrupt processing is high, the interrupt processing means is caused to perform the interrupt processing. If the priority of interrupt processing is low, normal periodic scheduling is performed. This enables periodic scheduling and priority control of interrupt processing that occurs aperiodically such as error processing.

On the other hand, in the computer system according to the third aspect of the present invention, the interrupt generator and the counter are operated by the clock from the hardware timer, the interrupt is generated from the interrupt generator to the scheduling execution means at each time slot time, and the counter is generated. The time slot value of each time is set in the register from. The scheduling execution means, when an interrupt occurs at each time slot time, goes to the register and obtains the time slot value corresponding to the current time. Using this time slot value, the same scheduling process as in the first aspect of the invention is performed. By using a hardware timer as the timer and automatically setting the time slot value in the register, the load on the system can be reduced and the processing speed can be improved.

[0017]

EXAMPLES Example 1. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a part related to scheduling of a computer system according to the first embodiment. In the figure, reference numeral 26 denotes a newly provided scheduling mode selection unit, which checks from the task information 12 whether or not there is a task that is less than the minimum reference period during the execution cycle of the activated task, and if there is, a priority scheduling as a scheduling mode. The mode is selected, and if not present, the conventional periodic scheduling mode is selected. 27 is a scheduling mode signal output as a selection result by the scheduling mode selection unit 26. 11 receives the scheduling mode signal 17 from the scheduling mode selection unit 26, performs the same operation as the conventional one in the periodic scheduling mode, and assigns the execution level 1 to all the time slots in the priority scheduling mode. This function is realized by the time slot allocation means 11c shown in FIG. Others are the same as the conventional system.

FIG. 2 is a functional block diagram showing the internal structure of the scheduling mode selection unit 26. In the figure, 26a is an execution cycle discriminating means for discriminating the execution cycle of each task based on the task information 12, and 26b is an execution cycle discriminating means for discriminating the execution cycle of each task based on the discrimination result of the execution cycle discriminating means 26a. A classifying means for classifying up to levels, 26c a comparing means for judging whether or not the execution cycle of the execution level in which the tasks of the minimum execution cycle are classified by the classification means 26b is shorter than the minimum reference cycle,
26d is a scheduling mode switching means for switching between a conventional periodic scheduling mode and a priority scheduling mode in which a task having a minimum execution period is assigned to all time slots as a new scheduling mode as a new scheduling mode. The output of the scheduling mode switching means 26d becomes the scheduling mode signal 27. The execution cycle determination means 26a and the classification means 26
b is an execution cycle discrimination means 11a and a classification means 11b (see FIG.
7)). Therefore, it is possible to provide only one set of these and share them with the time slot allocation unit 11 and the scheduling mode selection unit 26.

Next, the time slot allocation method in this embodiment will be described with reference to the flow charts of FIGS. First, in the scheduling mode selection unit 26, the execution cycle determination unit 26a determines the execution cycles of all the startup tasks, and the classification unit 26b classifies the execution levels according to the execution cycle (ST31). For example, execution cycle 50ms
Tasks are classified into execution level 1, tasks with an execution cycle of 70 ms are classified into execution level 2, and so on. Next, the scheduling mode selection unit 26 compares the execution cycle of the execution level 1 to which the task of the minimum execution cycle belongs and the minimum reference cycle by the comparison means 26c (ST32), and if the cycle of the execution level 1 is smaller, The priority mode is selected by the scheduling mode switching means 26d (ST34), and if larger, the periodic scheduling mode similar to the conventional one is selected. (ST33).
Next, the time slot allocation unit 11 receives the scheduling mode signal 27 and checks this mode (ST35). If this is the priority scheduling mode, as shown in FIG. Execution level 1 is assigned to slots 1 to N (ST36). When the scheduling mode is the periodic scheduling mode, the same processing as the conventional system is performed. That is, the time slot allocation unit 11 performs the following processing for execution levels 1 to M (ST37). For execution level 1, by multiplying the sum of all task execution times of execution level 1 by the ratio of the execution cycle of execution level 1 to the minimum reference cycle,
The time that the total execution time of the tasks of execution level 1 occupies within the minimum reference period is calculated (ST38). As described in the conventional example, for example, the execution cycle of the task of execution level 1 is 1
00 ms, total execution time of tasks at execution level 1 is 40
ms, when the minimum reference period is 50 ms, 40 × (50/1
00) = 20 ms is the required value. That is, the execution level 1 requires an execution time of 20 ms within the minimum reference period. The result is divided by the time slot time, the number after the decimal point is rounded up, and the number of time slots required for execution level 1 within the minimum reference period is obtained (ST39). In the above example, when the time slot time is 10 ms, 20/10 = 2, so two time slots are required. The above processing is similarly repeated from execution level 2 to M (ST40), and the number of time slots required for each execution level is obtained. Next, the number of time slots required for the execution time of the system required to execute the task is obtained (ST41). With the above, the number of time slots required by each execution level can be calculated. However, if the total exceeds the number N of time slots of the minimum reference period, the maximum execution load will be exceeded and control will not be possible. When N is compared (ST42) and the total exceeds the number of time slots N, the necessary number of time slots are sequentially stored in the time slot management table 211 from the execution level 1, and when the table is satisfied, the remaining levels are stored. Are ignored (ST44). If N is larger, there is no problem and the values are stored in the time slot management table 211 in order from execution level 1 (ST43). This completes the allocation of execution levels to time slots.

Execution of scheduling after time slot allocation is performed in the same manner as the conventional means. At this time, when the time slot management table 211 is generated as shown in FIG. 5 in the priority scheduling mode, the flow chart of FIG. 21 shown in the conventional example becomes as shown in FIG. After obtaining the execution level 1 (ST212), the level management tables 212a to 212c are checked from the execution level 1 according to FIG. 22, and the queuing task found first is executed. As a result,
The execution level 1 is given the highest priority, and the execution level M is given the lowest priority. That is, since the execution level 1 is acquired in any time slot and the execution task is determined according to the execution level search in FIG. 22, unless a task with a small execution level ends,
Large tasks are not executed. As a result, priority scheduling is realized in which a task having a lower execution level has a higher priority. In this case, FIG. 16 shown in the conventional example becomes as shown in FIG.

Example 2. FIG. 8 is a configuration diagram of a part related to the scheduling of the computer system of the second embodiment. The present embodiment is different from the first embodiment in FIG. 1 in that an interrupt generation unit 28 that notifies the scheduling execution unit 13 of the occurrence of an aperiodic event such as an error occurrence by an interrupt, and an interrupt that performs processing when an interrupt occurs. A processing unit 29 and a priority information storage unit 30 for storing priority information between a predetermined periodic task and the interrupt processing are provided. And the scheduling execution unit 1
3 normally performs the periodic scheduling as in the first embodiment, and when an interrupt (including the interrupt type) 31 is input from the interrupt generation unit 28 due to an error occurrence or the like, the priority information 32 from the priority information storage unit 30. If the priority of the interrupt processing is higher than that of the periodic task, the interrupt processing request (including the interrupt type) 3
3 is sent to the interrupt processing unit 29 so that the execution of the periodic task is temporarily interrupted and the interrupt processing is performed.

As shown in FIG. 9, the interrupt generation unit 28 has an interrupt type notification table 28a, an interrupt generation notification table 28b, and an execution task monitoring unit 28c. In the following, an error interrupt will be taken as an example. explain. When any error occurs in the task under execution 28d of the computer system, its interrupt type 28e is written in the interrupt type table 28a, and the interrupt generation signal 28f is set in the interrupt generation notification table 28b. on the other hand,
The execution task monitoring unit 28c uses the interrupt notification table 2
8b is polled at regular intervals, and when the interrupt generation signal 28g from the table 28b is set, the interrupt type 28h is acquired from the interrupt type notification table 28a, and the interrupt type 28h is sent to the scheduling execution unit 13 by the interrupt 31. After the processing is completed, the interrupt occurrence notification table 28b is again displayed.
Go into polling. On the other hand, the interrupt processing unit 29
As shown in FIG. 10, the interrupt type notification table 29a
And an interrupt processing request notification table 29b, an interrupt handler 29c, and a plurality of interrupt processing routines (1) 29d to (n) 29f corresponding to interrupt types.
When the scheduling executing unit 13 receives the interrupt 31 including the interrupt type from the interrupt generating unit 28, the scheduling executing unit 13 compares the priority of the interrupt processing corresponding to the interrupt type with the priority of the periodic task, and if the priority of the interrupt processing is higher, The interrupt type 33b is written in the interrupt type notification table 29a of the interrupt processing unit 29, and then the interrupt processing request 33a is set in the interrupt processing request notification table 29b. On the other hand, the interrupt handler 29c
Polls the interrupt processing request notification table 29b at regular intervals, and if the interrupt processing request 29g from the table 29b is set, the interrupt type notification table 2
The interrupt type 29h is acquired from 9a, the interrupt processing start signals 29i to 29k are output accordingly, and one of the interrupt processing routines (1) 29d to (n) 29f is started. When the processing is completed, polling of the interrupt processing request notification table 29b is started again.

Next, the scheduling operation of this embodiment will be described with reference to the flow chart of FIG. 11. First, the scheduling execution unit 13 checks whether or not there is an interrupt (ST111). If there is no interrupt, the same as in the first embodiment. Perform periodic scheduling of. If there is an interrupt, the following processing is performed. Priority information storage unit 3 in which priorities between interrupt processing and periodic tasks are stored in advance
From 0, the priority information 32 of the interrupt process and the periodic task is obtained and compared (ST112). If the priority of the interrupt process is high, the interrupt process is executed (ST114) and the interrupt is cleared (ST115).
If the priority of the interrupt processing is low, the interrupt is pending (ST113) and the normal periodic scheduling in the first embodiment is performed. However, if there is no execution task in this periodic scheduling (ST
124), the pending interrupt is processed using this time slot (ST125 → ST126). After the interrupt processing, the interrupt is cleared (ST127). With the above operation, it is possible to perform periodic scheduling and priority control of interrupt processing that occurs aperiodically such as error processing. That is, in the conventional example and the first embodiment,
Only the tasks designated in advance by the user and assigned to the time slot management table 211 can be executed. However, by adding the interrupt generation unit 28 and the interrupt processing unit 29 as described above, error processing that occurs aperiodically can be performed. By setting the priority to be high in advance, the periodic scheduling can be temporarily suspended and executed. In the present embodiment, the one in which the interrupt processing function as described above is added to the one in the first embodiment in FIG. 1 has been described, but the present invention can be applied to the conventional example in FIG.

Example 3. FIG. 13 is a configuration diagram of a part related to the scheduling of the computer system of the third embodiment.
This embodiment is based on the S / W timer 1 in the embodiment 1 of FIG.
4, the time slot calculation unit 16 and the time slot information storage unit 18 are configured by hardware. That is, 34 is a hardware (hereinafter abbreviated as H / W) timer which replaces the S / W timer 14 of FIG. 1, and is originally included in the computer system. Reference numeral 35 is an interrupt generator that generates an interrupt 37 to the scheduling execution unit 13 at each time slot time based on the clock 36 from the H / W timer 34, and 38 to 40 are each based on the clock 36 from the H / W timer 34. The N number of counters for counting the time slot values 1 to N, respectively, and the interrupt generator 35 and the counters 38 to 40 are provided in place of the time slot calculation unit 16 of FIG. Bits 41 corresponding to the time slot values 1 to N are set by the outputs 42 of the counters 38 to 40, and the time slot value 43 at the current time is set by the scheduling execution unit 13 every time an interrupt is generated from the interrupt generator 35. Is a time slot register that is read out, and is provided in place of the time slot information storage section 18 of FIG.

Next, the scheduling operation of this embodiment will be described with reference to the flow chart of FIG. Using the clock 36 of the H / W timer 34, the interrupt generator 35 generates an interrupt 37 to the scheduling execution unit 13 at each time slot time. The counters (1) 38 to 40 (N) 40 use the clock 36 of the H / W timer 34 to count the predetermined time slot values 1 to N, respectively, and time slot register 41 at each minimum reference period.
Set the corresponding bit of. Scheduling execution unit 1
When the interrupt generator 35 receives an interrupt 37 for each time slot time, it goes to the time slot register 41 and obtains the time slot value 43 from the set bit (ST141). Using this time slot value, the same scheduling process as in the first embodiment is performed, and H / W
After waiting for the timer interrupt (ST145), the process returns to the acquisition of the next time slot value and the above operation is repeated. By using the H / W timer as the timer and automatically setting the time slot value in the register, the load on the system can be reduced and the processing speed can be improved. That is, in the first embodiment, all the processes such as the process of acquiring the current time, the calculation of the time slot, and the notification of the time slot change interrupt to the scheduling execution unit 13 are performed by software by using the S / W timer function of the operating system. Has been realized. In this case, it is necessary to hold the previous value of the time slot, and the overhead time (system time in Fig. 7)
Has the drawback of becoming large. On the other hand, when the above functions are realized by hardware such as an interrupt generator, a counter, and a register using the H / W timer as in the present embodiment, it is not necessary to hold the previous value of the time slot. , Overhead can be reduced, and high-speed scheduling is possible.

[0026]

As described above, according to the first aspect of the present invention, in a computer system having a function of managing and scheduling a plurality of tasks having a unique execution cycle and execution time, An execution cycle discriminating means for discriminating the execution cycle, a classifying means for classifying each task from a short execution level to a long execution level based on the discrimination result of the execution cycle discriminating means, and a task start-up periodically. A time slot assigning means for assigning the execution level to a time slot, which is a time unit obtained by dividing a minimum reference period, which is a reference when checking, by a predetermined value,
Comparison means for determining whether or not the execution cycle of the execution level in which the tasks of the minimum execution cycle are classified is shorter than the minimum reference cycle, and based on the comparison result, each of the executions according to the cycle preset in each time slot A scheduling mode switching means for switching between a periodic scheduling mode for assigning a level and a priority scheduling mode for assigning an execution level in which tasks with a minimum execution period are assigned to all time slots, and a time slot corresponding to the current time. Scheduling execution means for executing task scheduling from the execution level, and when the execution cycle of the execution level into which the tasks of the minimum execution cycle are classified is shorter than the minimum reference cycle by the comparison means, the scheduling mode switching Means are usually periodic Switching from the scheduling mode to the priority scheduling mode, based on which the time slot allocating means allocates the execution level in which the tasks of the minimum execution cycle are classified to all the time slots, the periodic scheduling is performed as much as possible. By doing so, the load on the processor is evened out, and if there are tasks with non-schedulable cycles, they will be executed with the highest priority, and scheduling corresponding to tasks of all cycles will be possible. The effect of becoming

Further, according to the second aspect of the invention, the execution cycle determining means for determining the execution cycle of each task, and the execution of each task from the short execution level to the long execution cycle are executed based on the determination result of the execution cycle determining means. A classifying means for classifying the levels up to a level, and a time slot allocating means for allocating the execution level to a time slot which is a time unit obtained by dividing a minimum reference cycle serving as a reference for periodically checking the activation of a task by a predetermined value. An interrupt generation for notifying the scheduling execution means of the occurrence of an aperiodic event such as an error by providing a scheduling execution means for executing task scheduling from the execution level assigned to the time slot corresponding to the current time Means and interrupt processing means for performing processing when the interrupt occurs, and When the interrupt processing has a higher priority than the periodic task on the basis of the predetermined priority of the periodic task and the interrupt processing at the time of occurrence of the interrupt, the tasking execution means temporarily suspends the execution of the periodic task. Since the interrupt processing means is made to execute the interrupt processing, periodic scheduling,
It is possible to obtain the effect of enabling priority control of interrupt processing that occurs aperiodically such as error processing.

On the other hand, according to the third invention, like the first invention, each task is executed based on the execution cycle judging means for judging the execution cycle of each task and the judgment result of this execution cycle judging means. A classifier that classifies the execution level with a short cycle to a long execution level, and the above execution in a time slot that is a time unit obtained by dividing a minimum reference cycle, which is a reference when periodically checking task activation, by a predetermined value. A time slot assigning means for assigning a level, a comparing means for determining whether or not the execution cycle of the execution level into which the tasks of the minimum execution cycle are classified is shorter than the minimum reference cycle, and based on the comparison result, each time slot is assigned to A periodic scheduling mode in which each of the above execution levels is assigned according to a preset cycle, and a task with the minimum execution cycle is divided into all time slots. A scheduling mode switching means for switching between the priority scheduling mode for allocating the assigned execution level and a scheduling execution means for executing task scheduling from the execution level assigned to the time slot corresponding to the current time, and a hardware timer An interrupt generator that generates an interrupt to the scheduling execution means at each time slot time based on a clock, a counter that counts each time slot value based on a clock from a hardware timer, and a time slot value is set by the counter. Each time an interrupt is generated from the interrupt generator, the scheduling execution means reads out the time slot value at the current time, and the comparison means classifies the tasks with the minimum execution cycle. When the execution cycle of the execution levels is determined to less than the minimum reference period,
The scheduling mode switching means switches from the normal periodic scheduling mode to the priority scheduling mode, and based on this, the time slot allocating means allocates the execution level in which the tasks of the minimum execution cycle are classified to all the time slots. Therefore, the same effect as the first invention can be obtained, and
By using the H / W timer as the timer and automatically setting the time slot value in the register, the load on the system can be reduced and the processing speed can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a part related to scheduling of a computer system according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram showing an internal configuration of a scheduling mode selection unit in FIG.

FIG. 3 is a flowchart showing operations of a scheduling mode selection unit and a timeslot allocation unit of FIG.

FIG. 4 is a flowchart showing a sequel to FIG. 3;

FIG. 5 is a detailed diagram of a time slot corresponding task information table at the time of priority scheduling.

FIG. 6 is a flowchart showing an operation of a scheduling execution unit at the time of priority scheduling.

FIG. 7 is a diagram showing a task execution state at the time of priority scheduling.

FIG. 8 is a configuration diagram of a part related to scheduling of a computer system according to a second embodiment of the present invention.

9 is an internal configuration diagram of the interrupt generation unit of FIG.

10 is an internal configuration diagram of the interrupt processing unit of FIG.

11 is a flowchart showing the scheduling operation of FIG.

FIG. 12 is a flowchart showing a sequel to FIG. 11;

FIG. 13 is a configuration diagram of a part related to scheduling of a computer system according to a third embodiment of the present invention.

14 is a flowchart showing the scheduling operation of FIG.

FIG. 15 is a configuration diagram of a part related to scheduling of a conventional computer system.

FIG. 16 is a diagram showing a task execution state during scheduling.

FIG. 17 is a functional block diagram showing an internal configuration of a time slot allocation unit.

FIG. 18 is a detailed diagram of a time slot corresponding task information table.

19 is a flowchart showing the operation of the time slot allocation unit in FIG.

FIG. 20 is a flowchart showing a sequel to FIG. 19;

FIG. 21 is a flowchart showing the operation of the scheduling execution unit.

FIG. 22 is a diagram showing the order of checking execution levels.

[Explanation of symbols]

Reference Signs List 11 time slot allocation unit 11a execution cycle determination unit 11b classification unit 11c time slot allocation unit 12 task information 13 scheduling execution unit (scheduling execution unit) 14 S / W timer 15 fixed period interrupt 16 time slot calculation unit 17 time slot change interrupt 18 Time slot information storage unit 19 Time slot value (changed value) 20 Time slot value (current value) 21 Time slot corresponding task information table 22 Table information (current value) 23 Table information (changed value) 24 Activation task queuing unit 25 Activation Request task 26 Scheduling mode selection unit 26a Execution cycle determination unit 26b Classification unit 26c Comparison unit 26d Scheduling mode switching unit 27 Scheduling mode signal 28 Interrupt generation unit (Interrupt generating unit) 29 Interrupt processing unit (Interrupt processing unit) 30 Priority information storage unit 31 Interrupt (including interrupt type) 32 Priority information 33 Interrupt processing request (including interrupt type) 34 H / W timer 35 Interrupt generator 36 Clock 37 Interrupt 38-40 Counter 41 Time slot register 42 Counter output 43 Time slot value 211 Time slot management table 212a-212c Level management table 213a1-213an, 213b1, 213c1, 2
13c2 task management table

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[Procedure amendment]

[Submission date] May 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

First, the concept of periodic scheduling will be described with reference to FIG. The minimum reference cycle in the figure is the reference cycle when the activation of tasks is checked periodically, and is the minimum cycle for scheduling application tasks 1 to L (L is the number of tasks) that are executed periodically. is there. A time slot is a time unit obtained by dividing the above-mentioned minimum reference period by a predetermined value N (determined by the user according to the system), and the scheduler selects the execution tasks 1 to L for each time slot time. The execution level is a set of a plurality of tasks obtained by classifying the execution tasks 1 to L for each cycle, and the execution levels 1 to N are assigned to the time slots 1 to N.
M is allocated (allocation method will be described later). When executing the scheduling, the scheduler preferentially executes a task waiting for activation of the execution level assigned to the time slot in a certain time slot (a method of selecting the execution level will be described later).

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

In the example of FIG. 16, execution level 1 is assigned to time slot 1 and time slot 2, execution level 2 is assigned to time slot 3, and execution level M is assigned to time slot (N-1). The execution level selection time and the time slot calculation time are spare time slots (α) for the system time required for each time slot process , and the execution level 1 is assigned. Two tasks, task 1 and task 2, belong to execution level 1, task 3 belongs to execution level 2, and task L belongs to execution level M. At the time of scheduling, a time slot calculation unit described later calculates a time slot value from the value of the timer. For each minimum reference cycle, the execution
Bell's task can be
Start request, but different run levels start at the same time
If requested, start each time slot as follows:
The switching of the request execution level is executed. In time slot 1, execution level 1 is selected and task 1 of execution level 1 is being executed. Also in the time slot 2, the execution level 1 is selected and the task 1 is executed in the same manner. The execution level 2 is selected in the time slot 3, and the belonging task 3 of the execution level 2 is executed.
Since the time slot N is a spare time slot, an unexecuted task is executed within the minimum reference period. The execution level selection as described above is repeated every minimum reference period.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Execution of scheduling after time slot allocation is performed in the same manner as the conventional means. At this time, when the time slot management table 211 is generated as shown in FIG. 5 in the priority scheduling mode, the flow chart of FIG. 21 shown in the conventional example becomes as shown in FIG. After obtaining the execution level 1 ( ST221 ), the level management tables 212a to 212c are checked from the execution level 1 according to FIG. 22, and the first queuing task found is executed. As a result,
The execution level 1 is given the highest priority, and the execution level M is given the lowest priority. That is, since the execution level 1 is acquired in any time slot and the execution task is determined according to the execution level search in FIG. 22, unless a task with a small execution level ends,
Large tasks are not executed. As a result, priority scheduling is realized in which a task having a lower execution level has a higher priority. In this case, FIG. 16 shown in the conventional example becomes as shown in FIG.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

Next, the scheduling operation of this embodiment will be described with reference to the flow chart of FIG. Using the clock 36 of the H / W timer 34, the interrupt generator 35 generates an interrupt 37 to the scheduling execution unit 13 at each time slot time. The counters (1) 38 to 40 (N) 40 use the clock 36 of the H / W timer 34 to count the predetermined time slot values 1 to N, respectively, and time slot register 41 at each minimum reference period.
Set the corresponding bit of. Scheduling execution unit 1
When the interrupt generator 35 receives an interrupt 37 for each time slot time, it goes to the time slot register 41 and obtains the time slot value 43 from the set bit (ST141). The scheduling execution unit 13
After acquiring the imslot value, the time slot register 41
To reset. Using this time slot value, the same scheduling process as that of the first embodiment is performed, waiting for the H / W timer interrupt (ST145), returning to the acquisition of the next time slot value, and the above operation is repeated. H on the timer
By using the / W timer and automatically setting the time slot value in the register, the load on the system can be reduced and the processing speed can be improved. That is, Example 1
In the software, the S / W timer function of the operating system is used to implement all the processes of acquiring the current time, calculating the time slot, and notifying the scheduling execution unit 13 of the time slot change interrupt. In this case, there is a drawback that the previous value of the time slot needs to be held and the overhead time (system time in FIG. 7) becomes large. On the other hand, when the above functions are realized by hardware such as an interrupt generator, a counter, and a register using the H / W timer as in the present embodiment, it is not necessary to hold the previous value of the time slot. , Overhead can be reduced, and high-speed scheduling is possible.

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure correction 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 11

[Correction method] Change

[Correction content]

FIG. 11

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 19

[Correction method] Change

[Correction content]

FIG. 19

Claims (3)

[Claims] 1. In a computer system having a function of managing and scheduling a plurality of tasks each having a unique execution cycle and execution time, an execution cycle determination means for determining the execution cycle of each task, and this execution cycle determination means. Based on the determination result of, the classification means for classifying each task into the execution level with a short execution cycle to the execution level with a long execution cycle, and the minimum reference cycle used as a reference when checking the activation of the task are divided by a predetermined value. A time slot assigning unit that assigns the execution level to a time slot that is a time unit, and a comparing unit that determines whether or not the execution period of the execution level in which the tasks of the minimum execution period are classified is shorter than the minimum reference period, Based on the result of this comparison, a periodic schedule for assigning the above execution level to each time slot according to a preset period Scheduling mode switching means for switching a ring mode and a priority scheduling mode in which a task having a minimum execution period is assigned to all time slots, and a task scheduling from the execution level assigned to the time slot corresponding to the current time. The scheduling mode switching means is configured to execute a normal cycle when it is determined by the comparison means that the execution cycle of the execution level in which the tasks of the minimum execution cycle are classified is shorter than the minimum reference cycle. From the dynamic scheduling mode to the priority scheduling mode, and based on this, the time slot allocating means allocates to all time slots an execution level in which tasks with the minimum execution period are classified. Temu. 2. In a computer system having a function of managing and scheduling a plurality of tasks each having a unique execution cycle and execution time, an execution cycle determination means for determining the execution cycle of each task, and this execution cycle determination means. Based on the determination result of, the classification means for classifying each task into the execution level with a short execution cycle to the execution level with a long execution cycle, and the minimum reference cycle used as a reference when checking the activation of the task are divided by a predetermined value. A time slot assigning means for assigning the above execution level to a time slot which is a time unit, a scheduling executing means for executing task scheduling from the execution level assigned to the time slot corresponding to the current time, and an aperiodic operation such as error occurrence. Interrupt generation that notifies the above scheduling execution means of event occurrence by interrupt Means, and interrupt processing means for performing processing when the interrupt occurs, the scheduling execution means, when the interrupt occurs, the interrupt processing is performed periodically based on the predetermined periodic task and the priority of the interrupt processing. A computer system characterized in that, when the priority is higher than that of the task, the execution of the periodic task is temporarily interrupted and the interrupt processing means is caused to execute interrupt processing. 3. A computer system having a function of managing and scheduling a plurality of tasks having a unique execution cycle and execution time, and an execution cycle determining means for determining the execution cycle of each task, and this execution cycle determining means. Based on the determination result of, the classification means for classifying each task into the execution level with a short execution cycle to the execution level with a long execution cycle, and the minimum reference cycle used as a reference when checking the activation of the task are divided by a predetermined value. A time slot assigning unit that assigns the execution level to a time slot that is a time unit, and a comparing unit that determines whether or not the execution period of the execution level in which the tasks of the minimum execution period are classified is shorter than the minimum reference period, Based on the result of this comparison, a periodic schedule for assigning each of the above execution levels to each time slot according to a preset period. Scheduling mode switching means for switching between the scheduling mode and the priority scheduling mode that assigns the execution level in which the tasks of the minimum execution period are assigned to all time slots, and the task scheduling is performed from the execution level assigned to the time slot corresponding to the current time. A scheduling execution means for executing, an interrupt generator for generating an interrupt to the scheduling execution means at each time slot time based on a clock from a hardware timer, and a counter for counting each time slot value based on the clock from the hardware timer. And a register in which the time slot value is set by the counter and the time slot value at the current time is read by the scheduling execution means each time an interrupt is generated from the interrupt generator. Provided, when the execution cycle of the execution level minimum execution cycle of the task is classified by the comparison means it determines that less than a minimum reference period,
The scheduling mode switching means switches from the normal periodic scheduling mode to the priority scheduling mode, and based on this, the time slot allocating means allocates the execution level in which the tasks of the minimum execution cycle are classified to all the time slots. And computer system.