JP2003108391A - Task management apparatus, task management program and embedding device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress increase in overhead when conducting aging in a realtime OS employing a priority scheduling method. SOLUTION: By using a port list representing the priority of the task concatenated to a plurality of linearly concatenated task queue ports, each executable task is managed by every priority. Consequently, the overhead when conducting aging can be suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a task management device, a task management program and an embedded device for executing a task having the highest priority among a plurality of executable tasks.

[0002]

2. Description of the Related Art For example, in a real-time OS (Operating System) based on the μITRON specification, a priority scheduling method is basically used as a scheduling method for selecting a task to be executed next from among executable tasks. In the priority scheduling method, a plurality of executable tasks are managed for each priority. And
Among these tasks, the task with the highest priority is executed next.

However, in this method, even if the task is in the READY state, if the task has a lower priority than other tasks in the READY state, the task is kept waiting.

If there are a plurality of tasks with the highest priority, the tasks will be executed in the order in which they are in the ready state.
If it becomes ready for execution later, it may not be executed for a long time.

As described above, in the real-time OS which employs the priority scheduling method, the task is not executed (scheduled) for a long period of time, and as a result, the task is in a starvation state in which the execution time and execution frequency of the task are reduced. May fall.

Therefore, the CPU (Central Pro
cessing unit) TSS that allocates time evenly to each task
There is also a (Time Sharing System) that attempts to avoid task starvation by scheduling tasks.

In a real-time OS that also uses TSS for task scheduling, for example, a process called aging is performed for tasks having different priorities, and a process called rotate is performed for tasks having the same priority.

Aging is a process of periodically raising the priority of a task having a lower priority than a task having the highest priority among the tasks in the executable state. Aging involves a process called drop, in which a task whose priority has been raised by aging is executed and then the priority of the task is restored.

In addition, the rotate is a process of periodically, when there are a plurality of tasks having the highest priority, by rotating the task having the earliest execution order to the end and raising the execution order of the other tasks.

The tasks 404A, 404B, 404C, ... Which are targets of aging, rotation, etc. are, for example, a task queue table 42 as shown in FIG.
It was managed for each priority using 0.

The task queue table 420 is a table having a one-dimensional array structure. Each element 421 of the array
, 0, 1, 2, ..., (MAX_PRI-2), (MAX_PRI-1)
Index is given. These indexes represent the priority of the task.

The priority of each task is represented by holding the pointer of the task queue 403, which is the queue of the task, in the element 421 whose index indicates the priority (connecting the task queue 403).

In this example, the task queue 403 including the task with the higher priority has a smaller index value to which the task queue 403 is linked. Task queue 403 linked to element 4211 with index "1"
The task 404A included in R has the highest priority.

The run queue index 422 is an element 4 in which a task queue (run queue) 403R including a task having the highest priority, that is, a task to be executed is connected.
It represents the index of 211. In the example of FIG. 25 (a),
The value of the run queue index 422 is “1”.

The task priority is basically based on a preset base priority. For example, a task queue 403 including a task 404C whose base priority value is "3"
Are connected to each other by the element 421 whose index is "3".
Is.

When performing aging or rotation, such task queue table 420 is operated. When performing aging, the value of the variable run_ix held by the run queue index 422 is initialized in advance.

When the value of the variable run_ix held by the run queue index 422 is initialized, steps S2601 to S2603 as shown in FIG. 26 are performed. These procedures will be described by taking the state of the task queue table 420 shown in FIG. 25A as an example. First, 0 is assigned to the variable run_ix held by the run queue index 422 (S2601). Next, it is determined whether the task queue 403 is linked to the element 421 whose index value of the task queue table 420 is run_ix. Here, the task queue 403 is not linked to the element 421 whose index value is “0”. When it is determined that the task queue 403 is not linked to the element 421 of the run_ix having the index value of the task queue table 420,
The value of the variable run_ix is incremented by 1 (S26
03). At this time, the value of the variable run_ix becomes “1”.

Then, in step S2602, step S2603 is repeated until it is determined that the value of the index of the task queue table 420 is linked to the element 421 of run_ix. Figure 25
In the case of the example of (a), the element 4 whose index value is "1"
Since the task queue 403 is connected to 211, the initialization process ends without performing step S2603 again.

In this way, the task queue 403 is stored in the variable run_ix held by the run queue index 422.
Of the indexes of the elements 421 that are linked with each other, that is, the minimum value (that is, the index value indicating the highest priority)
Is set. Then aging is done.

In aging, as shown in FIG. 27, first, (run_ix + 1) is assigned to the variable i representing the index (S2701). At this time, the variable i representing the index becomes 2. Then the index value is (run_ix
It is determined whether the task queue 403 is connected to the element 421 of +1) (S2702).

When it is determined that the task queue 403 is connected to the element 421 having the index value (run_ix + 1), the task queue 403 is connected to the tail of the run queue 403R including the task with the highest priority. (S2703).

In the example of FIG. 25A, the task queue 403 is not linked to the element 421 whose index value is "2". Element 4 with index value (run_ix + 1)
If it is determined that the task queue 403 is not connected to the task 21, the variable i is incremented by 1 (S2
704). As a result, the variable i becomes 3.

Next, it is determined whether or not the task queue 403 is linked to the element 421 with the index i (S2705).

At this time, the variable i is 3, and the task queue 403 is connected to the element 421 having the index "3". When it is determined that the task queue 403 is connected to the element 421 with the index i, the address represented by the pointer to the task queue 403 is assigned to the pointer held by the element 421 with the index (i-1). (S2706). As a result, the task queue 403 linked to the element 421 having the index “3” is linked to the element 421 having the index “2”, and the priority of the task 404C included in the task queue 403 is set. Only 1 went up.

In step S2705, when it is determined that the task queue 403 is not linked to the element 421 having the index i, or after step S2706, the variable i is set to the maximum priority value (MAX_PRI-1). It is determined whether they are equal (S2707).

The variable i is the maximum value of the priority (MAX_PRI
-1) until it is determined whether or not it is equal to step S270.
The procedure from 4 to step S2707 is repeated.

As a result, the determination in step S2705 is made for all the elements 421 whose index is larger than the run queue index 422, and if the task queue 403 is linked, as shown in FIG. Task 404 included in task queue 403
The priority of C, 404D, and 404E is increased by 1.

When a task whose priority has been increased by the aging as described above is executed, the task is dropped. Run queue 403R is executed
The task to be dropped is located at the head of the run queue 403R because it is the task at the head.

Here, it is assumed that the state of the task queue table 420 immediately before the drop is as shown in FIG. 28 (a). That is, it is assumed that there is a task 404d having a base priority value of "4" at the head of the run queue 403R.

The drop will be described by taking the state shown in FIG. 28A as an example. First, as shown in FIG.
The task 404d (target of the drop) at the head of the run queue 403R is deleted from the run queue 403R (S2901).

Next, the deleted task 404d is linked to the end of the task queue 403 to which the element 421 having the same base priority value base_pri of the task 404d and the index value is linked (S2902). in this case,
The deleted task 404d is linked to the task queue 403 linked to the element 421 whose index value is "4".

Next, it is judged whether or not the task included in the run queue 403R is only the deleted task 404d (S2903). When the task included in the run queue 403R is only the deleted task 404d, the variable ru retained by the run queue index 422
The value of n_ix is incremented by 1 (S290
4). Further, it is determined whether or not the task is linked to the element 421 having the same index value as the variable run_ix (S2905). When it is determined that the task is not connected to the element 421 having the same variable run_ix and the same index value, the element 42 having the same variable run_ix and the same index value is determined.
Until it is determined that the task is linked to step 1, step S
2904 is repeated.

Then, in step S2903, the task included in the run queue 403R is the deleted task 40.
If it is determined that it was not only 4d, or step S29
After 05, the drop ends. In the example of FIG. 28A, since the task included in the run queue 403R is not only the deleted task 404d, steps S2904 and S2.
905 is not performed, and the state after the drop is as shown in FIG. 28 (b).

To explain rotation, first, as shown in FIG. 30, it is determined whether or not the number of tasks included in the run queue 403R is only one (S3001). If the number of tasks included in the run queue 403R is only one, the rotation ends as it is. If the number of tasks included in the run queue 403R is not only one, the task at the head of the run queue 403R is deleted (S3002), and the relevant task is assigned to the run queue 4
It is linked to the end of 03R.

[0035]

The problem of the above-mentioned prior art is that the maximum value of the priority (that is, the number of elements 421).
Is larger or the number of task queues 403 to be reconnected is larger, the time required for the aging process is increased and the overhead of the OS is increased. Since it is necessary to prohibit interrupts during the aging process described above, the interrupt responsiveness is deteriorated, which is a serious problem especially for real-time OSs.

The present invention has been made in view of the above problems in the prior art, and is a task management device, task management program, and built-in system capable of suppressing an increase in the overhead during aging and accompanying drop. The purpose is to provide a device.

[0037]

The present invention employs the following means in order to achieve the above object. That is, the present invention is premised on a task management device provided with an executable task management means for managing each task for each priority based on a preset priority set for each of a plurality of executable tasks. Among the tasks managed by this executable task management means, the task with the highest priority is executed. The task is executed by the scheduling means also included in the task management device. The scheduling means also gives the executable task management means an instruction for aging to raise the priority of the task having the lower priority than the task having the highest priority.

In carrying out this aging, the executable task management means operates a list in which the order of a plurality of linearly connected elements represents the priority of the task associated with the element. A specific aspect of this list is the port list 401 shown in FIG. The task queue port 402 corresponds to the element in the port list 401. The order of the task queue port 402, specifically the value of its index, represents the priority of the task associated with the task queue port 402.

When performing aging, the operation performed on the port list 401 is the task queue port 40 whose index indicates the highest priority among the task queue ports 402 associated with the task.
21 and the task queue port 4022 in the next order of the task queue port 402 are deleted, and the task queue port 4023 in the next order is connected instead.

By this operation, as shown in FIG. 5A, the task queue ports 4023, 4024, and the like, task queue ports 40 after the task queue port 4023 are shown.
The priority of the task associated with 2 is raised.

As can be understood from the specific mode of such a list, according to the present invention, the highest priority element in the order of representing the highest priority among the elements with which the task is associated is followed by the elements in the order. If the elements are connected, the subsequent elements are connected to the element that is one after the other, so that it is not necessary to perform an operation for each of these elements. As a result, even if the number of elements increases in accordance with the maximum value of priority, it is possible to suppress an increase in overhead in aging.

Further, the executable task management means, when the task is associated with the element whose connection with the highest priority element is deleted, also performs the operation of associating the task with the highest priority element with respect to the list. .

Further, for the elements which are deleted from the connection with the highest priority element and are not associated with the task, for example, the elements at the end of the list may be reconnected in order.

By the way, the scheduling means instructs the executable task management means to drop the priority of the executed task among the tasks whose priority has been raised by aging to the set priority of the task. .

In this case, it is preferable that the executable task management means has a table in which each array element arrayed corresponding to the order of the elements of the list holds specific information for identifying each element of the list.

A concrete mode of this table is the port table 410 shown in FIG. Port table 410
In, the index of the arrayed elements 411 matches the order of the task queue ports 402 in the port list 401. This element 411 holds a pointer to the task queue port 402 as specific information.

Further, the element searching means sets the elements of the list in the setting priority order representing the same priority as the setting priority of the task to be dropped into the array element of the table corresponding to the setting priority order. Search using the stored specific information.

Then, at the time of dropping, the executable task management means performs an operation of associating the task of the drop target with the element of the list searched by the element searching means.

By performing the drop in this way, the elements of the list in the set priority order can be easily obtained, and the elements are sequentially traced from the head of the list to search for the element to which the task to be dropped is associated. There is no need. Therefore, the overhead in the drop can be suppressed accordingly.

Further, the element search means differs from the array elements arranged in the table in the order of the elements of the list specified by the specification information held by the array element, which is different from the order of the array element. It is preferable to hold an update index that indicates the order of the array element arranged at the topmost position among the array elements.

A specific mode of this update index is the update index 412 shown in FIG. 10 (b). The update index 412 holds the index value of the element 411 in the port table 410. Here, the update index 412 holds the value “2”. Element 411 whose index is "2"
The pointer held by 2 points to the task queue port 402A, which is in a different order from the corresponding task queue port 402 of the element 4112. Similarly, the elements 411 whose indexes are “3” or more are also different in order, but the element 4112 is the element closest to the head among the elements having different orders. Therefore, the update index 412 is the index value “2” of the element 4112.
Holding

As in the specific embodiment shown in FIG. 10 (b),
The order of the task queue port 402 pointed to by the pointer held by the element 411 and the task queue port 402 corresponding to the element 411 is different as a result of aging.

In such a state, the search result of the element search means may become inappropriate.

Therefore, when performing the search, the element search means determines whether or not the set priority order is after the order represented by the update index, and determines that the set priority order is after the order represented by the update index. In this case, the specific information held by the array elements that are arranged on the rearmost side of the array element corresponding to the highest priority element and that are arranged earlier than the order represented by the update index The operation of updating the elements of the list in 1 to be specified is performed in advance.

Here, it is assumed that the port list 401 and the port table 410 exist in the state as shown in FIG. The value held by the update index 412 is "2", and the setting priority of the task to be dropped is "3". In this case, FIG. 13 (b)
Element 4111 corresponding to the highest priority element
The pointer (specific information) held by the element 411 arranged on the rearmost side of the element and positioned before the order represented by the update index, that is, the element 4112 and the element 4113 having the index value “3” in the next order is updated. It will be.

If the state shown in FIG. 13B is reached,
The request search means can perform an appropriate search. Moreover, the specific information is updated only for the minimum necessary array elements. Therefore, it is possible to suppress the increase of the overhead due to the update, and as a result, it contributes to the suppression of the increase of the overhead in the drop.

The specific information of the remaining array elements may be updated in the idle state, for example. Also,
Along with the update of the specific information, an operation of updating the order represented by the update index next to the array element for which the specific information is updated is performed.

The port list is often stored in the high speed memory area of the memory areas consisting of the low speed memory and the high speed memory. Therefore, in order to reduce the high-speed memory area consumed by the port list, it is necessary to reduce the capacity of the port list.

Therefore, in the port list 401, only the holding elements associated with the tasks are linearly linked. This holding element holds a value indicating the priority of the associated task (hereinafter referred to as "holding element priority"). A specific mode of the list in which the holding elements are linked is the port list 401 shown in FIG. In FIG. 14, the holding element corresponds to the task queue port 408.
It is 0.

In such a port list 401,
Only the task associated with the first task queue port 4080 (highest priority holding element) is executed by the executable task management means.

The scheduling means gives an aging instruction to the executable task management means. The aging here means a task queue port 408 other than the task queue port 4080 having the highest holding element priority.
2 is an operation to raise the priority of the holding element.

When the port list 401 shown in FIG. 16 is aged, as shown in FIG. 18, the task queue port 4081 and subsequent task queue ports 408 are shown.
The holding element priorities “3” and “4” of 1,4082 become “2” and “3”. Further, in the state where the port list 401 is shown in FIG. 18, when the executable task management means performs aging again, the task queue port 4
The holding element priorities of 081 and 4082 are "1" and "2".

By performing aging in this way, the task queue port 4081 and the task queue port 4080
The holding element priorities of and become equal. When the holding element priorities of the first task queue port 4080 and the next task queue port 4081 become equal, the executable task management means sets the task 4041 associated with the next task queue port 4081 to the first task queue. Associate with port 4080. Then, the executable task management means deletes the connection between the task queue port 4080 and the next task queue port 4081, and connects the next task queue port 4082 to the task queue port 4080.

As a result, the task 4 associated with the next task queue port 4081 as shown in FIG.
041 will be associated with the task queue port 4080.

Further, the executable task management means can reduce the memory area consumed by the port list 401 by deleting the next task queue port 4081 from which no task is associated with the task queue port 4081.

The scheduling means 102 also gives a drop instruction to the executable task management means.
The term “drop” here means that the executed task in the task queue 403R associated with the first task queue port 4080 having the highest holding element priority due to aging is the holding element priority corresponding to the setting priority of the task. Is associated with the task queue port that holds the.

For example, when the task 4041 having the setting priority "3" shown in FIG. 21 is the target of the drop, the executable task management means holds the holding element search means with the holding element priority "3". The queue port is searched for from the port list 401, and the task 4041 to be dropped is associated with the detected task queue port 4081.

Further, for example, when the task 4042 shown in FIG. 22 is to be dropped, as shown in FIG. 23 corresponding to the set priority of the task 4042, the task queue port with the holding element priority “7” is It does not exist in the port list 401. In this case, the executable task management means uses the task queue port 40 whose holding element priority is "7".
83 is created, and the holding elements are arranged in the port list 4 so that the arrangement order of the port list 401 is the holding element priority order.
Add to 01. That is, task queue port 4083
23 is connected to the task queue port having the lowest holding element priority among the holding elements having the holding element priority higher than “7”, that is, the task queue port 4082 in FIG. Further, the task queue port 4083 is connected to the task queue port having the highest holding element priority among the holding elements having the holding element priority lower than "7", that is, the task queue port 4085 in FIG. Further, the task queue port 4083 is associated with the task 4042 to be dropped by the executable task management means.

As shown in FIG. 24, when the task is no longer associated with the task queue port 4080 having the highest holding element priority as a result of the execution of the drop, the executable task management means is task queue port 408.
The connection between 0 and the next task queue port 4081 is deleted. In this way, by deleting the task queue port 4080 that is no longer associated with a task, the capacity of the entire port list 401 can be reduced.

The invention as described above may be implemented not only as a task management apparatus but also as a task management program or a computer-readable recording medium such as a CDROM recording the task management program.

This task management program cooperates with hardware such as CPU and memory of the computer,
The computer is made to function as the task management device as described above.

Furthermore, if this task management program or the real-time OS in which it is installed is incorporated into, for example, a digital home appliance or a mobile phone, the task management apparatus will be implemented as such an embedded device.

[0073]

BEST MODE FOR CARRYING OUT THE INVENTION (Embodiment 1) Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, the present invention appears in a real-time OS that basically performs task scheduling by a priority scheduling method and also performs aging regularly. This real-time OS causes at least a computer to function as the task management device 1 as shown in FIG.

In the task management system 1, the system call processing means 101 receives the system call from the application 201 and notifies the scheduling means 102 of the task status change. In a real-time OS that conforms to the μITRON specifications, the task status is the execution status (RU
N), ready state (READY), waiting state (WAIT), dormant state (DORMANT), etc., and the state changes between these. For example, when the waiting state is released for the task in the waiting state, the state of the task changes to the executable state.

The scheduling means 102 assigns the CPU of the computer to the task to be executed among the tasks in the executable state, and instructs the dispatch means 103 to switch the tasks. The dispatch unit 103 executes task switching (dispatch) according to the instruction of the scheduling unit 102. By this switching, the state of the task in the ready state changes to the running state. Further, the dispatch means 103 also saves and restores the context, that is, the state and environment of the task being processed.

The scheduling means 102 also periodically issues aging, drop, and rotate instructions to the ready queue management means 104.

The ready queue management means 104 manages a plurality of tasks in the ready state for each priority, and performs aging, drop and rotation according to the instruction of the scheduling means 102.

The ready queue management means 104 manages the task for each priority by using the port list 401 as shown in FIG. The port list 401 has a list structure in which a plurality of elements (task queue ports) 402 are linearly connected.

The index of each task queue port 402 represents a priority, and the task queue port 402 at the head of the port list 401 is sequentially numbered 0, 1, 2, ..., (MAX_P
RI-2) and (MAX_PRI-1) indexes are given. Here, MAX_PRI represents the maximum value of the priority. That is, as many task queue ports 402 as the number of priorities are prepared.

Each task queue port 402 has the next lower priority than the task queue port 40 by one.
By holding the pointer to 2, the task queue port 402 in the next order is connected. However, the task queue port 402T at the end of the port list 401 is
Do not hold pointers to other task queue ports 402 (hold Null pointers).

Further, the task queue port 402 holds the pointer to the task queue 403,
It may also be linked to the task queue 403.

The task queue 403 is a queue (queue) using a list of tasks, for example. The task holds a preset base priority, and basically, the task queue port 40 to which the task queue 403 is connected
The value of the priority represented by the index of 2 and the value of the base priority of the tasks included in the task queue 403 are the same. In Fig. 1, tasks are represented by ○, and the base priority value is ○.
It is represented by the number in, for example, task queue port 4
The value of the base priority of the task included in the task queue 403 connected to the 021 is “1” which is the same as the value of the index of the task queue port 4021. However, the value of the (current) priority of the task may not match the value of the base priority due to aging or the like.

When the task queue 403 includes a plurality of tasks, it means that the tasks have the same priority. In this case, when there is another task that is in the ready state later, the task holds a pointer to the other task. The task that was in the earliest ready state is located at the head of the task queue 403 (the leftmost side in the drawing).

The run queue 403R is the task queue 40.
The task queue 403 has the highest priority among the three tasks. The ready queue management unit 104 notifies the scheduling unit 102 of the task in the ready state at the head of the tasks included in the run queue 403R as the task to be executed next. Run queue 403
R also includes tasks in the running state. The task in the execution state is located at the head of the run queue 403R.

The run queue port 402R holds a pointer to the task queue port 4021 to which the run queue 403R is connected. In addition, run queue index 4
Reference numeral 05 represents an index of the task queue port 4021 to which the run queue 403 is connected. In the example of FIG. 1, the run queue index 405 will represent “1”. Further, the port list head 406 holds a pointer to the task queue port 4020 at the head of the port list 401, and the port list tail 407 holds the task queue port 40 at the tail of the port list 401.
Holds a pointer to 2T.

When the scheduling means 102 gives an aging instruction, the ready queue management means 104 operates on such a port list 401.

When performing aging, the ready queue management means 104 initializes the value of the run queue index 405 and the pointer held in the run queue port 402R in advance.

As shown in FIG. 3, first, the ready queue management means 104 sets the pointer run_port held by the run queue port 402R and the variable run_ix held by the run queue index 405 to the address port_list_head indicated by the pointer held by the port list head 406. And 0 are respectively substituted (S301).

Next, the ready queue management means 104 judges whether or not the task queue 403 is connected to the task queue port 402 pointed to by the pointer run_port (S302). Whether or not the task queue 403 is connected is determined by whether or not the task queue port 402 indicated by the pointer run_port holds a pointer to the task queue 403.

If it is determined that the task queue 403 is connected to the task queue port 402, the initialization process is terminated. On the other hand, when it is determined that the task queue 403 is not connected to the task queue port 402, the address of the next task queue port 402 is assigned to the pointer run_port (S303), and the value of the variable run_ix of the run queue index 405 is set to 1 only. Increment (S304). The ready queue management means 104 repeats steps S303 and S304 until it is determined in step S302 that the task queue 403 is connected to the task queue port 402.

In the example of FIG. 1, the port list head 406.
Holds a pointer to the task queue port 4020. The address indicated by this pointer is the step S3.
Since the pointer is assigned to the pointer run_port in 01, the determination in step S302 is made in the task queue port 4020
Will be done. Task queue port 40
Since the task queue 403 is not linked to 20, the steps S303 and S304 are performed. The task queue port 402 in the next order is the task queue port 4021. Since the task queue 403 (run queue 403R) is connected to the task queue port 4021, the initialization process ends. Pointer run_po after initialization
rt represents the address of the task queue port 4021, and the value of the variable run_ix matches the index value of the task queue port 4021.

That is, by the initialization, the run queue port 402R holds a pointer to the task queue port 4021 to which the run queue 403R is linked, and the run queue index 405 sets the task queue port 402.
Holds an index of 1.

When performing aging through the above initialization processing, as shown in FIG. 4, the ready queue management means 104 first sets the next order connected to the task queue port 402 indicated by the pointer run_port. It is determined whether the task queue 403 is connected to the task queue port 402 (S401). That is, run queue 4
It is determined whether the task queue 403 is connected to the next task queue port 402 connected to the task queue port 402 to which 03R is connected.

If it is determined that the task queue 403 is connected to the next task queue port 402 that is connected to the task queue port 402 to which the run queue 403R is connected, the ready queue management means 104 determines 403 is linked to the end of the run queue 403R (S402).

When it is judged that the task queue 403 is not connected to the next task queue port 402 which is connected to the task queue port 402 to which the run queue 403R is connected, or after the step S402, the ready queue management is performed. The means 104 deletes the next task queue port 402 (S403). Run queue 403
To the task queue port 402 to which R is connected, the next task queue port 402 is connected instead of the next task queue port 402.

Next, the ready queue management means 104 replaces the deleted task queue port 402 with the port list 40.
It is connected to the end of 1 (S404). The deleted task queue port 402 is connected in the order next to the task queue port 402 that was the last task queue. The task queue port 402, which was the last one until then, can be immediately searched by the pointer held by the port list tail 407. Further, since the last task queue port 402 is changed in step S404, the ready queue management unit 104 substitutes the address of the deleted task queue port 402 into the pointer held by the port list tail 407.

In the example of FIG. 1, the task queue 403 is connected to the next task queue port 4022 connected to the task queue port 4021 to which the run queue 403R is connected.
Is not connected. Therefore, according to the determination in step S401, step S403 is performed without passing through step S402. In step S403, the task queue port 4021
Further, instead of the next task queue port 4022, the next task queue port 4023 is connected. Then, in step S404, the task queue port 402
2 are connected in the order next to the task queue port 402T that was at the end of the port list 401 until then. Figure 5
(A) shows the state of the port list 401 at this time.

As shown in FIG. 5A, the task 404 whose base priority value is "3" is a result of the above aging.
The task queue port 4023, to which the task queue 403 including 6 is connected, is connected in the order following the task queue port 4021. That is, the (current) priority of the task 4046 whose base priority value is “3” is increased by one to “2”. Similarly, the task queue port 40
The priority of the task 4046 included in the task queue 403 connected to the task queue port 402 subsequent to the order 23 is also increased by one. As is apparent from the flowchart of FIG. 4, the operation performed to raise the priority of the tasks included in the task queue 403 connected to these task queue ports 402 is basically only the operation in step S403. . Since the task queue port 402 is connected to the task queue port 402 in the next order and below, even if the task queue port 4023 is connected to the task queue port 4021, it is not necessary to operate each task queue port 402. Therefore, even if the maximum value of the priority is large (the number of task queue ports 402 is large), it is possible to avoid an increase in the overhead in aging.

To retain the maximum priority value, the deleted task queue port 402 needs to be linked to any part of the port list 401.
If you can connect to the end of the port list 401,
It is easy to search and does not affect the aging operation.

In the example of FIG. 5A, the task 4046 having the base priority value of "3" is included in the task queue 403 connected to the task queue port 4023, and the run queue 403R is still in the run queue 403R. Not included. Therefore, as long as tasks remain in the run queue 403R, the task 4046 having a base priority value of "3" is not executed, but aging is performed regularly.

For example, when aging is performed again from the state of FIG. 5A, the task queue 403 is connected to the next task queue port 4023 connected to the task queue port 4021 to which the run queue 403R is connected. ing. Therefore, step S402 is performed according to the determination in step S401. In step S402, the task queue 403 connected to the task queue port 4023 is connected to the end of the run queue port 403R. That is, as shown in FIG. 5B, the task 4046 having the base priority value of “3” has the base priority value of “1” at the end of the tasks included in the run queue port 403R. Tasks 4047 are linked in order. Therefore, if the task 4047 having a base priority value of "1" is deleted from the run queue 403R or the ready queue management means 104 executes rotation according to an instruction from the scheduling means 102, the base priority value is "3". The task 4046 is also executed.

When the task whose priority has been raised by the aging as described above is executed, the ready queue management means 104 drops the task according to the instruction of the scheduling means 102. Since the task at the head of the run queue 403R is executed, the task to be dropped is located at the head of the run queue 403R.

When dropping, as shown in FIG.
First, the ready queue management unit 104 uses the run queue 403.
The task (drop target) at the head of R is deleted from the run queue 403R (S601).

Next, the ready queue management means 104, for each pointer_run_port and variable _run_ix, the address indicated by the pointer run_port held by the run queue port 402R and the variable run_ held by the run queue index 405.
The value of ix is substituted (S602).

Next, the ready queue management means 104 uses the base priority value base_pri and the variable _run_i of the deleted task.
It is determined whether or not the value of x is equal (S603).

Value of base priority of deleted task base_p
If it determines that ri and the value of variable _run_ix are not equal,
The address of the next task queue port 402 connected to the task queue port 402 pointed to by pointer_run_port is assigned to pointer_run_port (S604). Further, the value of the variable _run_ix is incremented by 1 (S
605). Then, the ready queue management means 104 repeats steps S604 and S605 until it determines in step S603 that the base priority value base_pri of the deleted task is equal to the value of the variable _run_ix.

In step S603, when it is determined that the base priority value base_pri of the deleted task and the value of the variable _run_ix are equal, the ready queue management means 104 determines the task queue port 402 pointed to by the pointer _run_port at that time. Then, the deleted tasks are linked (S606).

Next, the ready queue management means 104 judges whether or not the tasks included in the run queue 403R are only the deleted tasks (S607).

When it is determined that the tasks included in the run queue 403R are only the deleted tasks, the ready queue management means 104 performs an update process for updating the pointer held by the run queue port 402R and the value of the run queue index 405. (S608).

As shown in FIG. 7, in this update processing, the ready queue management means 104 first puts the task queue 403 in the task queue port 402 pointed to by the pointer run_port.
It is determined whether R is connected (S701).

When it is determined that the task queue 403R is not connected to the task queue port 402 pointed to by the pointer run_port, the address of the next task queue port 402 connected to the task queue port 402 is set to
It is assigned to the pointer run_port (S702). Further, the value of the variable run_ix is incremented by 1 (S70
3). Then, the ready queue management unit 104 performs the procedure S.
In step 701, steps S702 and S703 are repeated until it is determined that the task queue 403R is connected to the task queue port 402 pointed to by the pointer run_port.

In step S701, the pointer run_port
Task queue port 402 points to the task queue 40
If it is determined that the 3Rs are connected, the update process ends.

When the update process is completed in this way or when it is determined in step S607 that the tasks included in the run queue 403R are not the only deleted tasks, the drop ends.

For example, the port list 401 immediately before the drop
It is assumed that the state of is as shown in FIG.
That is, the base priority value is "4" at the head of the run queue 403R connected to the task queue port 402a.
Task 4048 is located.

If a drop is performed in this state, first in step S601, the run queue 403R
Task 404 whose base priority value is “4” at the beginning of the
8 is deleted from the run queue 403R. Step S60
In 2, the pointer _run_port and the variable _run_ix,
The address of the task queue port 402a and the value “1” of the run queue index are substituted. Since the value "4" of the base priority and the value "1" of the variable _run_ix are not equal to each other, steps S604 and S6 are performed according to the determination in step S603.
05 is performed. In step S604, the next task queue port 40 connected to the task queue port 402a is connected.
The address of 2b is assigned to the pointer_run_port. In step S605, the value of variable _run_ix is incremented to "2". After step S605, step S603 is performed. Since the value of the variable _run_ix at this time is "2", it is not equal to the base priority value "4". Therefore, in accordance with the determination in step S603, step S60
4, S605 is repeated. As a result, the address of the task queue port 402c is assigned to the pointer_run_port, and the value of the variable _run_ix becomes “3”. After that, step S603 is performed, but the value of the variable _run_ix at this time is “3”, and therefore the value of the base priority is not equal to “4”. Therefore, steps S604 and S605 are performed, and the pointer_run_port is the task queue port 402d.
, And the value of the variable _run_ix is “4”.
That is, in the next step S603, the value of the variable _run_ix becomes equal to the base priority value “4”. Therefore, according to the determination in step S603, step S606
As shown in FIG. 8B, the task queue 403 including the deleted task 4048 whose priority value is “4” is displayed.
Is the task queue port 40 pointed to by the pointer _run_port
It is connected to 2d. In addition, in the example of FIG. 8A, in addition to the deleted task 4048 whose priority value is “4”, the task 404 whose priority value is “1” is stored in the run queue 403R.
Since 9 is also included, according to the determination in step S608, the drop ends without passing through step S609.

In the first embodiment described above, the task queue port 402 is the next task queue port 402.
A pointer to the task queue 403 and a pointer to the task queue 403 are held.
You may also hold the pointer to the task at the end of the. As a result, the operation of connecting another task queue 403 to the end of the task queue 403 can be performed at high speed.

In addition, operations on the port list 401, the task queue 403, etc. are performed by the C of the computer controlled by the above-mentioned real-time OS with respect to the memory of the computer respectively assigned to them.
It is realized by the PU performing an operation.

(Second Embodiment) In this second embodiment, the ready queue management means 104 has a task queue port search means 105 as shown in FIG.
The tasks are managed using not only the port list 401 but also the port table 410 and the update index 412 as shown in FIG.

The port table 410 is, for example, a table in which the same number of elements 411 as the maximum priority value MAX_PRI are arranged in correspondence with the order of the task queue ports 402. The index of each element 411 corresponds to the task priority value, and holds a pointer to the task queue port 402 having the same index in the initial state.

The task queue port retrieving means 105 uses the pointer held by the element 411 of the index corresponding to the priority having the same value as the base priority of the task to be dropped to find the task queue port 402 of the index. It is something to search for.

The update index 412 holds the smallest value among the indexes of the element 411 whose index does not match the task queue port 402 pointed to by the held pointer. In the initial state, the index values of all the elements 411 match the index values of the task queue port 402 pointed to by the pointer held by each element 411, so the variable upda held by the update index 412
The value of te_ix becomes MAX_PRI which is one more than (MAX_PRI-1).

When the scheduling means 102 gives an instruction such as aging, the ready queue management means 104
Operations are performed on the port list 401, the port table 410, the update index 412, and the like.

When performing aging, the ready queue management means 104, as in the above-described first embodiment, has a pointer run_port held by the run queue port 402R,
The variable run_ix held by the run queue index 405 is initialized.

The aging procedure performed by the ready queue management means 104 after this initialization is the same as described above from step S401 to step S404, as shown in FIG. In the second embodiment, the ready queue management means 1
04 performs step S1001 after step S404 and before ending aging.

In step S1001, the ready queue management means 104 stores the variable upda stored in the update index 412.
This is a procedure of substituting te_ix with a value obtained by adding 1 to the value of the variable run_ix held by the run queue index 405.

When aging is performed on the port list 401 and the port table 410 in the state shown in FIG. 10A, the task queue port 402 to which the run queue 403R is connected is shown in FIG. As shown in FIG. 5, the task queue ports 402B that are in sequence with the task queue port 402 are connected. Task queue port 4 that was in the next order of the task queue port 402
02A is linked to the end of the port list 401.

In step S1001, the value "2" obtained by adding 1 to the value "1" of the run queue index 405 is the variable upda held by the update index 412.
It is assigned to te_ix. As for the value of the variable update_ix held by the update index 412, the index of the task queue port 402 pointed to by the pointer held by the element 411 (element 4112 and subsequent elements) whose index is equal to or greater than this value is different from that element 411. It means that. For example, the index value of the task queue port 402A pointed to by the pointer held in the element 4112 whose index value is “2” is (MAX_PRI-1) after aging.
And is different from element 4112. In addition, the index value of the task queue port 402 pointed to by the pointer held in the element 411 having an index value of “3” or more decreases by 1 after aging. That is, the priority of the tasks included in the task queue 403 connected to these task queue ports 402 is increased by one.

Next, the case of performing the drop will be described. As shown in FIG. 12, first, the ready queue management means 104, similar to the first embodiment, executes the run queue 40.
The task at the head of 3R is deleted from the run queue 403R (S1201).

Next, the task queue port search means 105
Is the variable update_ix held by the update index 412
Value is larger than the base priority value base_pri of the deleted task (S1202).

Variable up held by update index 412
The value of date_ix is the base priority value bas of the deleted task
When it is determined that the value is equal to or less than e_pri, the task queue port search unit 105 uses the pointer held by the element 411 whose index value indicating the priority is (update_ix-1) and uses the task queue port 402 to which the pointer points.
To search. The task queue port search unit 105 updates the address of the next-order task queue port 402 of the searched task queue port 402 with the index value update_i.
Substitute the pointer held by the element 411 of x (S12
03). Further, the value of the variable update_ix is incremented by 1 (S1204). Then, the task queue port search unit 105 repeats steps S1203 and S1204 until it determines in step S1202 that the value of the variable update_ix held by the update index 412 is larger than the base priority value base_pri of the deleted task. .

In step S1202, when it is determined that the value of the variable update_ix held by the update index 412 is larger than the base priority value base_pri of the deleted task, the task queue port searching means 105 determines that the base priority value is the same. Element 41 with the same index value as base_pri
The pointer held by 1 is used to search the task queue port 402 pointed to by the pointer. The ready queue management unit 104 connects the deleted task to the end of the task queue 403 connected to the retrieved task queue port 402 (S1205).

Then, the ready queue management means 104
Similar to the first embodiment described above, it is determined whether the tasks included in the run queue 403R are only the deleted tasks (S1206). When the ready queue management unit 104 determines that the tasks included in the run queue 403R are only the deleted tasks, the ready queue management unit 104 performs an update process for updating the pointer held by the run queue port 402R and the value of the run queue index 405 (S120).
7).

For example, the port list 40 immediately before the drop
1. Assume that the state of the port table 410 is as shown in FIG. That is, the run queue 40
At the head of 3R, the task 40 whose base priority value is "3"
Suppose 40 was located. Also, update index 4
The value of the variable update_ix held by 12 is “2”.

If a drop is performed in this state, first in step S1201, the run queue 403
The task 4040 having the base priority value base_pri of “3” at the head of R is deleted from the run queue 403R.
The value of the variable update_ix is “2”, which is smaller than the base priority value base_pri “3” of the deleted task 4040. Therefore, according to the determination in step S1202, step S1202 is performed.
Step 1203 and step S1204 are performed. Step S1202
Then, an index smaller than the value of the variable update_ix by 1, that is, the element 4111 whose index value is “1”
The task queue port 402C pointed to by the pointer is searched using the pointer held by the. Variable update_ix
Since the index value of the task queue port 402 indicated by the pointer held by the element 411 having an index smaller than the value of is the same as that of the element 411, the search here is appropriately performed. Searched task queue port 4
02C holds a pointer to the next task queue port 402D. Therefore, the address represented by the pointer is the element 41 whose index value is "2".
It is assigned to the pointer held by 12. Next, step S1
At 204, the value of the variable update_ix is incremented by 1 and becomes “3”.

Even if it is incremented, the variable update_ix
Is the base priority value of the deleted task 4040.
Since it is the same "3" as base_pri, steps S1203 and S1204 are performed again according to the determination in step S1202. In step S1203, task queue port 4
The address indicated by the pointer to the task queue port 402E held by 02D is substituted for the pointer held by the element 411 whose index value is "3". Further, in step S1204, the value of the variable update_ix is set to "4".

After this, step S1202 is performed, but since the value of the variable update_ix is larger than the base priority value base_pri of the deleted task 4040, step S1205 is performed. In step S1205, the task queue port 4 pointed to by the pointer held by the element 411 of the index "3" having the same value as the base priority value base_pri.
02E is searched. This pointer has just been updated and the search is done properly. And FIG. 13 (b)
As shown in, the deleted task 40 is added at the end of the task queue 403 connected to the task queue port 402E.
40 are connected.

When the drop is performed in this way, it is necessary to trace the task queue port 402 from the beginning of the port list 401 one by one until the task queue port 402 to which the task queue 403 that links the deleted tasks is linked is determined. Disappear. If the pointer to the task queue port 402 held by the element 411 is appropriately updated, the task queue port 402 in the middle of the port list 401 can be obtained by the pointer. Further, the pointer to the task queue port 402 is updated at the time of dropping only for the minimum necessary elements 411. Therefore, even if drops occur more frequently than aging, it is possible to suppress an increase in overhead in drops.

As shown in FIG. 10B, if the value of the index of the element 411 is less than or equal to the value of the variable held by the post-drop update index 412, the task held by the element 411 Cue port 40
The pointer to 2 has not been updated. This update does not need to be performed at the time of dropping, and for example, these pointers may be updated when the system is in the idle state. In this update, the base priority value base_pri in step S1202 is replaced with the maximum priority value MAX_PRI, and steps S1202, S1203, and S1204 are performed.
Can be carried out.

Further, in the above-mentioned first and second embodiments,
The ready queue management means 104 may perform rotation according to an instruction from the scheduling means 102. Regarding the rotation process, for example, the procedure shown in FIG. 30 may be followed.

The task management device described above may be implemented as an embedded device such as a digital home appliance or a mobile phone. Unlike a general-purpose computer, an embedded device has a specific purpose, but like a general-purpose computer, it has a memory that stores a program and a processor that executes the program stored in the memory. In order to provide the embedded device with the system call processing means 101, the scheduling means 102, the dispatch means 103, and the ready queue management means 104, for example, the above-mentioned real-time OS mounted according to the embedded device is stored in the memory of the embedded device. You can leave it.

(Third Embodiment) In the third embodiment,
Aging performed on the port list 401 in which only task queue ports associated with tasks as shown in FIG. 14 are arranged will be described. Each task queue port holds a value representing the base priority value base_pri of the associated task as a holding element priority value ele_pri. The base priority value base_pri of the task associated with each task queue port and the retention element priority value ele_ple held in each task queue port may not match when aging is performed. Figure 1
4, the value ele_pri of the holding element priority of each task queue port 4080, 4082 is set to the task queue port 408.
It is represented by the numerical value written in 0,4082.
Furthermore, each task queue port is connected to the next task queue port by holding a pointer to the next task queue port.

As an example of the method of creating such a port list 401, there is a method as shown in FIG.

When a predetermined task goes from the waiting state or the dormant state to the ready state, the creating means in charge of creating the port list 401 substitutes the address port_list_head indicated by the port list head 406 into the pointer held by the now port 409. (FIG. 15, S1501).

Next, the creating means uses the NOWPORT 409.
Task queue port pointed to by (attention task queue port)
The holding element priority value ele_pri of is compared with the base priority value base_pri of the task in the executable state (FIG. 15, S1502). When the holding element priority value ele_pri of the target task queue port is smaller than the base priority value base_pri, the creating unit determines whether or not another task queue port is connected to the target task queue port ( (FIG. 15, S1503). Whether or not another task queue port is connected to the target task queue port is determined by whether or not the target task queue port holds a pointer to another task queue port.

When it is determined that another task queue port is connected, the creating means substitutes the address of the next task queue port connected to the target task queue port into the pointer held by the now port 409. (FIG. 15, S1504). And the creating means is
The comparison in step S1502 is performed again.

On the other hand, when it is determined in step S1503 that another task queue port is not connected, the creating means gives priority to the holding element having the same value as the base priority value base_pri of the task in the executable state. Degree value ele_pr
Create a task queue port that holds i. The creating means holds a pointer to the created task queue port in the target task queue port. In this way
The newly created task queue port and the target task queue port are linked (FIG. 15, S1505).

Then, the creating means associates the task in the ready state with the newly connected task queue port (FIG. 15, S1506).

In step S1502, if it is determined that the holding element priority value ele_pri of the task queue port of interest is equal to or greater than the base priority value base_pri, the creating means determines the holding element priority value ele_pri and the base. It is determined whether or not the priority value base_pri is the same (FIG. 15, S).
1507).

When it is determined that they are not the same, the creating means determines the base priority value base_pri of the task in the ready state.
Create a task queue port that holds the value ele_pri of the holding element priority that is the same value as. The creating unit connects the created task queue port to the task queue port whose arrangement order in the port list 401 is one before the task queue port of interest (FIG. 15, S1508). Note that another task queue port may be connected to the target task queue port in step S1508. In this case, the creating means causes the newly connected task queue port to hold a pointer to another (next-order) task queue port connected to the target task queue port. The task queue port newly created in this way and the task queue port next to the task queue port of interest are linked.

When the task queue ports created in step S1508 are linked, the creating means associates the task in the ready state with the newly linked task queue port (FIG. 15, S1506).

If it is determined in step S1507 that the holding element priority value ele_pri and the base priority value base_pri are the same, the creating means determines that the task in the task queue port of interest is ready to execute. Are associated with each other (FIG. 15, S1509).

For example, when the port list 401 is in the state shown in FIG. 14, the base priority value base_pri is "3".
It is assumed that the task 4041, which is a task, goes from the sleep state to the executable state. Then, the creating means substitutes the address port_list_head (here, the address of the task queue port 4080) indicated by the pointer held by the port list head 406 into the pointer held by the now port 409 in step S1501.

Next, in step S1502, the creating means sets the holding element priority value of the task queue port 4080 of interest.
ele_pri "1" and the task 404 in the ready state
The base priority value of 1 base_pri “3” is compared. In this case, the base priority value base_pri of the task 4041 is larger, and the task queue port 4082 is connected to the target task queue port 4080.
The address 2 is assigned to the pointer held by the now port 409. The value ele_pri of the holding element priority of the task queue port 4082 is “4”. When the address of the task queue port 4082 is substituted, the process of creating the port list 401 returns to step S1502.

Task queue port 4 in now port 409
Since the address 082 is input, the holding element priority value ele_pri of the task queue port 4082 of interest becomes larger than the base priority value base_pri of the task 4041. Therefore, the process of creating the port list is performed in step S.
The procedure moves from step 1501 to step S1508 through step S1507.

Here, the creating means creates the task queue port 4081 which holds the holding element priority value ele_pri of the same value as the base priority value base_pri of the task 4041. The creating means connects the created task queue port 4081 to the task queue port 4080 immediately before the task queue port 4082 of interest. Furthermore, the creating means is configured to newly connect the task queue port 408.
The task queue port 4082 of interest is connected to 1.

Then, in step S1506, the creating means associates the task 4041 with the newly connected task queue port 4081, and the port list 401 is shown in FIG.
The state becomes as shown in.

The creating means may be separate means from the ready queue managing means 104, or the ready queue managing means 104 functions as the creating means to perform the port list creating process. You can

Also in the third embodiment, the first embodiment
Similarly to the above, the ready queue management means 104 executes the task at the head of the run queue 403R.
The run queue 403R described below is the task queue 403 associated with the task queue port having the highest holding element priority.

When there is an aging instruction from the scheduling means 102, the ready queue management means 104
Operates the port list 401.

When there is an aging instruction, the ready queue management means 104 determines whether or not another task queue port is connected to the task queue port of the address port_list_head indicated by the pointer held by the port list head 406 ( FIG. 17, S1701).

When it is determined that another task queue port is not connected to the task queue port, the ready queue management means 104 ends the aging.

On the other hand, when it is determined that another task queue port is connected to the task queue port, the ready queue management means 104 causes the port list head 406.
The address of the task queue port pointed to by nowport 40
9 is assigned to the pointer held by S9 (FIG. 17, S170).
2).

In the ready queue management means 104, the holding element priority value ele_pri of the task queue port of interest pointed to by the now port 409 indicates the holding element priority of the next task queue port connected to the task queue port of interest. It is determined whether it is the same as the value obtained by subtracting one from the value ele_pri (FIG. 17, S1703).

When it is determined that they are the same, the ready queue management means 104 changes the task queue port connected to the target task queue port from the next task queue port to the next task queue port (FIG. 17, S170).
4). However, if there is no next task queue port, the task queue port is not linked to the next task queue port. At this time, the ready queue management means 104 associates the task associated with the next task queue port with the task queue port of interest. Then, the ready queue management means 104 deletes the next task queue port (FIG. 17, S170).
5). The port list 401 as described above is often stored in the high speed memory area of the memory including the low speed memory and the high speed memory. Since the high speed memory area has a relatively small capacity, it is necessary to reduce the high speed memory area consumed by the port list 401. Therefore, in step S1705, it is preferable that the next task port whose task is no longer associated is deleted from the memory.

After deleting the next task queue port in step S1705 or determining that they are not the same in step S1703, the ready queue management means 104 determines that another task queue port is connected to the target task queue port. It is determined whether or not (S1706 in FIG. 17).

If it is determined that the task queue port of interest is not connected to another task queue port,
The ready queue management means 104 ends the aging.

On the other hand, when it is determined that another task queue port is connected to the target task queue port, the ready queue managing means 104 substitutes the address of the other task queue port into the NOW port (FIG. 17, S170).
7). As a result, the other task queue port connected to the target task queue port becomes the target task queue port. Then, the ready queue management means 10
4 decrements the value ele_pri of the holding element priority of the task queue port that has newly become the target task queue port by 1 (FIG. 17, S1708).

After decrementing the holding element priority value ele_pri, the ready queue management means 104 determines again whether or not another task queue port is connected to the target task queue port (FIG. 17, S170).
6). When the ready queue management unit 104 determines that another task queue port is connected, the ready queue management unit 104 performs steps S1707 and S1708 again.

In the example of FIG. 16, the port list head 40
6 holds a pointer to the task queue port 4080. Since the task queue port 4081 is connected to the task queue port 4080, the aging process proceeds to step 1702 via step S1701. In step S1702, the ready queue management means 104 substitutes the address of the task queue port 4080 into the pointer held by the now port 409.

Subsequently, in step S1703, the ready queue management means 104 determines the task queue port 4 of interest.
The holding element priority value ele_pri of 080 and the task queue port 408 next to the task queue port 4080 of interest.
It is determined whether or not the value obtained by subtracting 1 from the holding element priority value ele_pri of 1 is the same. The value ele_pri of the holding element priority of the task queue port 4080 is "1", and the value ele_pr of the holding element priority of the task queue port 4081 in the next order.
Since i is “3”, the ready queue management means 10
4 determines that they are not the same. As a result, the aging process moves to step S1706.

Since the task queue port 4081 is connected to the task queue port 4080 of interest, the ready queue management means 104 performs the procedure 1706 through the procedure 1706. Here, the ready queue management means 104 substitutes the address of the next task queue port 4081 into the pointer held by the now port 409.
As a result, the next task queue port 4081 becomes the target task queue port 4081. In step S1708, the ready queue management unit 104 decrements the holding element priority value ele_pri held by the new target task queue port 4081 by 1, and determines in step 1706.

Further, as shown in FIG. 16, since the task queue port 4082 is connected to the target task queue port 4081, the ready queue managing means 104 is provided.
Performs step S1707 again. That is, the address of the next task queue port 4082 is assigned to the pointer held by the now port 409. Further, the ready queue management means 104 newly adds the task queue port 408 of interest.
The task queue port 4082 that has become 2 decrements the value ele_pri of the holding element priority held by the task queue port 4082, and the determination in step 1706 is performed.

As shown in FIG. 16, the task queue port 4082 of interest is not connected to any other task queue port, so that the ready queue management means 104 ends the aging.

As a result of the aging, as shown in FIG. 18, the holding element priorities of the task queue ports 4081 and 4082 are increased from "3" / "4" to "2" / "3".

With the port list 401 shown in FIG. 18, the aging instruction is issued again to the ready queue management means 10.
4, the ready queue management means 104 goes through step S1701 to step 17 as in the previous aging.
Do 02. Here again, the address represented by the pointer held by the port list head 406 is the address of the task queue port 4080. Therefore, step S1702
The address of the task queue port 4080 is assigned to the pointer held by the now port 409.

In the previous aging process, the value ele_pr of the holding element priority of the next task queue port 4081 is set.
i is decremented by 1 and becomes "2". Therefore, the value ele_pri of the holding element priority of the task queue port 4080 of interest and the next task queue port 4081
It is the same as the value obtained by subtracting one from the holding element priority value ele_pri of. Therefore, the process of this aging is the procedure S
When step 1703 is performed, the process proceeds to step S1704.

In step S1704, the ready queue management means 104 deletes the connection between the target task queue port 4080 and the next task queue port 4081 as shown in FIG. The task queue port 4082 is connected. The ready queue management unit 104 associates the task 4041 associated with the next task queue port 4081 with the last task associated with the task queue port 4080.

The ready queue management means 104
Deletes the next task queue port 4081 from the memory as well, and the aging process moves to step S1706.

Here, the task queue port 408 of interest is
Since the task queue port 4082 is connected to 0, the task management means 104 executes the procedure S as described above.
1707 and step S1708 are performed, and aging is completed.

As described above, by performing the aging twice, the task 4041 associated with the task queue port 4081 as shown in FIG. 19 is associated with the task queue port 4080 having the highest holding element priority. Therefore, task queue port 4 by aging
The task 4041 associated with 080 is executed by performing rotation or the like.

(Embodiment 4) As in Embodiment 3,
Among the tasks associated with the run queue 403R due to aging, the executed task is the target of the drop performed by the ready queue management unit 104.

Upon performing the drop, the ready management means 104, as shown in FIG.
The task at the head of 03R is deleted from the run queue 403R (FIG. 20, S2001). Next, the ready queue management means 104 substitutes the address of the task queue port pointed to by the port list head 406 into the pointer held by the now port 409 (FIG. 20, S2002).

The task queue port search means 105 provided in the ready queue management means 104 stores the value ele_pri of the holding element priority of the task queue port of interest and the base priority value base_pri of the task to be dropped. The comparison is made (FIG. 20, S2003).

If the base priority value base_pri of the task is larger than the holding element priority value ele_pri, the task queue port search means 105 determines whether another task queue port is connected to the target task queue port. (FIG. 20, S2004).

If it is determined that they are connected, the task queue port searching means 105 determines whether the base priority value base_pri of the task is the same as the holding element priority value ele_pri (FIG. 20, S2005). .

When it is determined that they are not the same, the task queue port searching means 105 substitutes the address of another task queue port connected to the target task queue port into the pointer held by the now port 409 (FIG. 2).
0, S2006). Then, the task queue port search means 105 performs the comparison in step S2003 again.

On the other hand, in step S2004, when the task queue port search means 105 determines that another task queue port is not connected, the drop process proceeds to step S2007.

Here, the ready queue management means 104
Is the base priority value ba of the task that is the target of the drop.
Create a task queue port that holds the holding element priority value ele_pri, which is the same value as se_pri. The ready queue management means 104 connects the created task queue port to the target task queue port (FIG. 20, S2007).
Then, the ready queue management means 104 sets the address of the newly connected task queue port to the now port 40.
9 is assigned to the pointer held by S9 (FIG. 20, S200).
8). Then, the ready queue management means 104 associates the task to be dropped with the newly connected task queue port (FIG. 20, S2009).

If it is determined in step S2005 that the task queue port searching means 105 are the same,
The ready queue management unit 104 associates the task with the task queue port of interest (FIG. 20, S2009).

Further, when the task queue port searching means 105 determines in step S2003 that the value base_pri of the task priority base_pri is less than or equal to the value ele_pri of the holding element priority of the task queue port of interest, the drop processing is the procedure. The process moves to S2010. Here, the ready queue management means 104 determines the value of the base priority of the task base_p.
Create a task queue port that holds the holding element priority value ele_pri, which is the same value as ri. The ready queue management means 104 connects the created task queue port to the task queue port that is one before the task queue port of interest in the arrangement order in the port list 401. Further, the ready queue management means 104 connects the task queue port of interest to the newly connected task queue port (FIG. 20, S2010).

When the created task queue port is linked to the target task queue port, the ready queue management means 104 associates the task to be dropped with the linked task queue port (FIG. 20, S2009).

For example, the base priority value base shown in FIG.
When the task 4041 whose _pri is “3” is to be dropped, the ready queue management means 104 uses the procedure 200
At 1, the task 4041 is deleted from the run queue 403R.

In step S2002, the ready queue management means 104 substitutes the address of the first task queue port 4080 into the pointer held by the now port 409.

In this example, the target task queue port 40
The holding element priority value ele_pri of 80 is “1”, and the base priority value of the task 4041 to be dropped
Since the base_pri is “3”, the drop process is step S.
The procedure moves from 2003 to step S2004. As shown in FIG. 21, since the task queue port 4081 is connected to the target task queue port 4080, the drop processing moves to step S2005.

Here, as described above, the value ele_pri of the holding element priority of the task queue port 4080 of interest and the value base_p of the base priority of the task 4041 to be dropped.
Since it is not the same as ri, the drop process is step S200.
Go to 6.

In step S2006, the task queue port search means 105 causes the task queue port 4080 of interest.
The address of the next task queue port 4081 connected to is assigned to the pointer held by the now port 409. As a result, the task queue port 4081 becomes the target task queue port 4081. As a result, the drop processing returns to step S2003.

The value ele_pri of the holding element priority of the target task queue port 4081 is “3”, and the task 4041
Since the base priority value base_pri of is also “3”, the drop processing moves from step S2003 to step S2004.

As shown in FIG. 21, since the task queue port 4082 is also connected to the task queue port 4081 of interest, the drop processing moves to step S2005.

At this point, the task queue port 4 of interest
081 holding element priority value ele_pri and task 4041
Since it is the same as the base priority value base_pri of, the drop processing proceeds to step S2009. Step S200
9, the ready queue management means 104 executes the task 4
041 is associated with the task queue port 4081 of interest,
The port list 401 is in the state shown in FIG.

In this state, if there is a drop instruction again, the ready queue management means 10 is operated in step S2001.
4 is the task 4042 at the head of the run queue 403R (holding element priority value ele_pri is “7”)
Delete from 3R.

Next, in step S2002, the ready queue management means 104 causes the task queue port 408 at the head of the queue.
The address of 0 is input to the pointer held by the now port 409. Here, since the base priority value base_pri of the task 4042 is larger than the holding element priority value ele_pri of the task queue port 4080 of interest, the drop processing shifts from step S2003 to step S2004.

As shown in FIG. 22, the port list 401
The holding element priority value ele_pri is “3”, “4”,
“10” ... task queue ports 4081, 408
2, 4085 ... Are arranged. Therefore, the drop processing is performed in steps S2004, S2005, and S2005.
Since 2006 is repeated, the address of the task queue port whose holding element priority value ele_pri is "3", "4", or "10" is assigned to the pointer held by the now port 409 every time step S2006 is performed. .

In step S2006, the pointer held by the NOWPORT 409 sets the holding element priority value ele_pri to "1".
When the address of the task queue port 4085 of “0” is substituted, the value ele_pri of the holding element priority of the task queue port 4085 of interest is the base priority value b of the task 4042.
It will be larger than ase_pri. Therefore, the drop processing moves from step S2003 to step S2010.

When the procedure shifts to step S2010, the ready queue management means 104 has the same holding element priority value ele_pri as the base priority value base_pri of the task 4042.
A task queue port 4083 for holding is created. The ready queue management unit 104 replaces the created task queue port 4083 with the task queue port 4085 of interest.
Task queue port 4082 that is one order earlier than
Connect to. Further, the ready queue management means 104 connects the target task queue port 4085 to the newly connected task queue port 4083.

In step S2009, the ready queue management means 104 causes the newly connected task queue port 4
The task 4042 is linked to 083.

As a result, the port list 401 shown in FIG. 22 is brought into a state as shown in FIG.

When the port list 401 is in the state shown in FIG. 23, if the drop instruction is given again, the ready queue management means 104 deletes the task 4043 at the head of the run queue 403R from the run queue 403R.

As shown in FIG. 23, there is no task queue port holding the holding element priority value ele_pri of the same value as the base priority value base_pri “8” of the task 4043 in the port list 401. Therefore, task 4042
In the same manner as described above, the ready queue management means 104
A task queue port 4084 having a holding element priority value ele_pri of “8” is created, and the task queue port 4084 is connected to the task queue port 4083 as shown in FIG. Also, the task 4043 that is the target of the drop is
The ready queue management means 104 is associated with the task queue port 4084.

By this drop, a task is not associated with the task queue port 4080 at the head. In order to reduce the memory area consumed by the port list 401, the task queue port 4080 that is no longer associated with a task is deleted from the port list 401.

Therefore, in order to delete the first task queue port 4080 that is no longer associated with a task,
For example, the ready queue management unit 104 determines whether or not the task is associated with the task queue port 4080 indicated by the port list head 406 after the drop. When it is determined that the task queue port 4080 is not associated with a task, the ready queue management unit 104 deletes the task queue port 4080 from the port list 401.

In FIG. 24, when the task queue port 4080 pointed to by the port list head 406 is deleted, the ready queue management means 104 causes the port list head 4
The address held in 06 is the task queue port 4081 that newly becomes the task queue port 4081 at the beginning.
Update to the address.

As a result, only the task queue ports associated with the tasks are arranged in the port list 401.

The task management device described above may be implemented as an embedded device such as a digital home appliance or a mobile phone. Unlike a general-purpose computer, an embedded device has a specific purpose, but like a general-purpose computer, it has a memory that stores a program and a processor that executes the program stored in the memory. In order to provide the embedded device with the system call processing means 101, the scheduling means 102, the dispatch means 103, and the ready queue management means 104, for example, the above-mentioned real-time OS mounted according to the embedded device is stored in the memory of the embedded device. You can leave it.

[0215]

As described above, in the present invention, the order of a plurality of linearly connected elements indicates the priority of the task associated with the element, and An operation is performed in which the connection between the element in the order representing the highest priority and the element in the next order is deleted, and instead the elements in the next order are connected. Since the aging is performed by this operation, it is not necessary to perform the operation for each of the elements connected to the element one after another. Therefore, even if the number of elements increases according to the maximum value of the priority, it is possible to suppress an increase in overhead in aging.

Further, a table is prepared in which each array element arranged corresponding to the order of the elements of the list holds specific information for specifying the element of the list. This specific information is used to search the elements of the list in the order of indicating the same priority as the set priority of the task to be dropped. Then, if the operation of associating the task targeted for the drop with the element of the searched list is performed, it is not necessary to sequentially trace the elements from the head of the list and search for the element associated with the task targeted for the drop. Therefore, the overhead in the drop can be suppressed accordingly.

Further, among the array elements arranged in the table, the order of the elements of the list specified by the specifying information held by the array element is different from the one corresponding to the array element, and is the first array element. The update index indicating the order of the array elements arranged on the side is held. It is determined whether or not the order of indicating the same priority as the set priority of the task to be dropped is after the order of the update index. Then, when it is determined that the update index is after the order represented by the update index, the task is associated with the update index of the element corresponding to the element having the highest priority among the elements associated with the task. If the operation to update the specific information held by the array elements arranged before the indicated order to the one that identifies the list element in the corresponding order of the array element is performed in advance, the search can be performed properly. You can Moreover, since the specific information is updated only for the minimum necessary array elements, it is possible to suppress an increase in overhead associated with the update.

By arranging only the holding elements associated with tasks in the list, the capacity of the list can be reduced. In order to execute the aging for raising the priority of the task in such a list, an operation of raising the holding element priority of the holding element other than the highest priority holding element having the highest holding element priority may be performed. Since the aging is performed by this operation, it is not necessary to perform the operation of raising the priority of all the tasks associated with each holding element, and therefore the aging overhead can be suppressed.

Note that the memory area consumed by the list can be reduced by reducing the holding elements in the memory that are no longer associated with the task by aging. In particular, when the list is stored in a high-speed memory having a small capacity, the high-speed memory area consumed by the list can be reduced.

When a drop is executed for a list in which only holding elements are arranged, a list of operations for associating a task with a holding element having a holding element priority of the same value as the setting priority of the task to be dropped Do against. By this operation, the elements are sequentially traced from the beginning of the list,
There is no need to search for an element that associates the task that was the target of the drop. Therefore, the overhead in the drop can be suppressed accordingly.

When there is no holding element with the same holding element priority as the setting priority, a holding element for holding the holding element priority with the same value as the task setting priority is created, and the created holding Perform the operation to associate the task to be dropped with the element with respect to the list.

When the holding element is no longer associated with the highest priority holding element due to the drop, the highest priority holding element is deleted from the list. As a result, the capacity of the list can be reduced and the memory area consumed can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a port list according to the first embodiment.

FIG. 2 is a diagram showing a schematic configuration of a task management device according to the first embodiment.

FIG. 3 is a flowchart for explaining initialization processing of a run queue port and a run queue index according to the first embodiment.

FIG. 4 is a flowchart for explaining aging in the first embodiment.

FIG. 5 is a diagram showing a specific example of states before and after aging of the port list according to the first embodiment.

FIG. 6 is a flowchart for explaining a drop in the first embodiment.

FIG. 7 is a flowchart for explaining a process of updating a run queue port and a run queue index according to the first embodiment.

FIG. 8 is a diagram showing a specific example of states before and after dropping the port list according to the first embodiment.

FIG. 9 is a diagram showing a schematic configuration of a task management device according to the second embodiment.

FIG. 10 is a diagram showing a specific example of the states of the port list and port table before and after aging according to the second embodiment.

FIG. 11 is a flowchart for explaining aging in the second embodiment.

FIG. 12 is a flowchart for explaining a drop according to the second embodiment.

FIG. 13 is a diagram showing a specific example of a port list before dropping and a state after dropping the port table according to the second embodiment.

FIG. 14 is a diagram showing a port list according to the third embodiment.

FIG. 15 is a flowchart for explaining a process of associating a task in an executable state with a list according to the third embodiment.

FIG. 16 is a diagram showing a port list according to the third embodiment.

FIG. 17 is a flowchart for explaining aging in the third embodiment.

FIG. 18 is a diagram showing a port list after aging according to the third embodiment.

FIG. 19 is a diagram showing a port list after the second aging according to the third embodiment.

FIG. 20 is a flowchart for explaining a drop according to the fourth embodiment.

FIG. 21 is a diagram showing a state of a port list immediately before a drop according to the fourth embodiment.

FIG. 22 is a diagram showing the state of the port list after the first drop in the fourth embodiment.

FIG. 23 is a diagram showing a state of the port list after the second drop in the fourth embodiment.

FIG. 24 is a diagram showing the state of the port list after the third drop of the fourth embodiment.

FIG. 25 is a view showing a concrete example of a state of a task queue table used before and before and after aging.

FIG. 26 is a flowchart for explaining initialization processing of a run queue index when using a task queue table.

FIG. 27 is a flowchart for explaining aging when using a task queue table.

FIG. 28 is a diagram showing a specific example of the state of the task queue table before and after the drop.

FIG. 29 is a flowchart for explaining a drop when using a task queue table.

FIG. 30 is a flowchart for explaining rotation.

[Explanation of symbols]

1 task management device 101 system call processing means 102 scheduling means 103 dispatch means 104 ready queue management means 105 task queue port search means 401 port list 402, 4080-4085 task queue port 402R run queue port 403 task queue 403R run queue 4040-4043, 4046 ~ 4048 404A ~
404E, 404d Task 405 Run queue index 406 Port list head 407 Port list tail 409 Now port 410 Port table 411 Element 412 Update index

Claims (18)

[Claims] 1. An executable task management unit that manages each task for each priority based on a preset priority set for each of a plurality of executable tasks, and a task managed by the executable task management unit. A scheduling means for executing a task with the highest priority among them, and the scheduling means raises the priority of the task with lower priority than the task with the highest priority with respect to the executable task management means. In the task management device, the executable task management means has a list in which the order of a plurality of linearly connected elements represents the priority of the task associated with the element, When performing aging, the highest priority element in the order that represents the highest priority among the elements associated with the task, and the highest priority element Task management device that performs an operation for connecting instead to the list elements in the successive order to remove the connection between elements in the following order. 2. The executable task management means, when a task is associated with an element whose connection with the highest priority element has been deleted, also associates the task with the highest priority element in the list. The task management device according to claim 1, which is performed for the task management device. 3. The executable task management means also performs an operation of connecting elements that are deleted from the highest priority element and are not associated with a task, in the order following the last element in the list. The task management device according to claim 2, which is performed for 4. The scheduling means instructs the executable task management means to drop the priority of the executed task among the tasks whose priority has been raised by the aging to the set priority of the task. The executable task management means also provides a table in which each array element arranged corresponding to the order of the elements of the list holds specific information for identifying an element of the list, and a target of the drop. An element search for searching the elements of the list in the setting priority order indicating the same priority as the setting priority of the task using the specific information held in the array element of the table corresponding to the setting priority order And a means for performing the drop, the element of the list searched by the element search means is targeted for the drop. Task management device of claim 2, wherein performing an operation to associate the disk. 5. The element search unit is an array element in which the order of elements of the list specified by the specification information held by the array element is different from the array element corresponding to the array element. Retaining the update index indicating the order of the array element arranged at the most front side in the element, in performing the search, it is determined whether or not the setting priority order is after the order represented by the update index,
When it is determined that the set priority order is after the order represented by the update index, the set priority order is arranged on the rearmost side of the array element corresponding to the highest priority element and arranged before the order represented by the update index. The task management device according to claim 4, wherein an operation for updating the identification information held by the array element to identify an element of the list in an order corresponding to the array element is performed in advance. 6. The element search means, in the idle state, associates the specific information held by array elements arranged on the rearmost side of the order represented by the update index with the array element. The task management device according to claim 5, which performs an operation of updating the elements of the list in order to specify the elements. 7. The task according to claim 5, wherein the element search means also performs an operation of updating the order represented by the update index in the order next to the array element that has updated the specific information, in association with the update of the specific information. Management device. 8. A task management program for causing a computer to function as the task management device according to claim 1. 9. An embedded device equipped with the task management device according to claim 1. 10. An executable task management unit that manages each task for each priority based on a preset priority set for each of a plurality of executable tasks, and a task managed by the executable task management unit. A scheduling means for executing a task with the highest priority among them, and the scheduling means raises the priority of the task with lower priority than the task with the highest priority with respect to the executable task management means. In the task management device, the executable task management means associates tasks with each other, and only a holding element that holds a value representing the priority of the associated task is in the order according to the priority value. Has a list linked by, and when performing the aging, the highest priority holding element that is the holding element at the head of the list is required. Task management apparatus characterized by operating the value held retaining element other than the to the list. 11. The executable task management means, by performing the aging, when the values held by the highest-priority holding element and the next-order holding elements of the highest-priority holding element are equal, The task associated with the next-order holding element is associated with the highest-priority holding element, the connection between the highest-priority holding element and the next-order holding element is deleted, and the next-order holding element is set to the highest-ranking holding element. The operation for connecting to a priority holding element is performed on the list.
Task management device described in. 12. The task management device according to claim 11, wherein the executable task management unit deletes the next-order holding element also from the memory that stores the list. 13. The scheduling means associates with the executable task management means the executed task among the tasks associated with the highest priority holding element by the aging with the set priority of the task. The executable task management unit holds a value corresponding to the set priority of the task to be dropped associated with the highest priority holding element. A holding element search means for searching a holding element is provided, and when performing the drop, an operation of associating a task to be dropped with a holding element searched by the holding element search means is performed on the list. 10. The task management device according to item 10. 14. When the executable task management means cannot detect a holding element holding a value corresponding to the setting priority of the task to be dropped as a result of the search by the holding element searching means. , Adding a holding element holding a value corresponding to the setting priority of the task to be dropped to the list, and performing an operation of associating the task to be dropped with the holding element with respect to the list. Item 13. The task management device according to item 13. 15. The executable task management means connects the highest priority holding element and the next-order holding element when a task is no longer associated with the highest priority holding element as a result of the execution of the drop. The task management device according to claim 13, wherein the task management device is deleted and the highest priority holding element is deleted from the top of the list. 16. The task management device according to claim 10, wherein the executable task management means places each holding element in a high speed memory area of a high speed memory and a low speed memory provided in the system. 17. A task management program for causing a computer to function as the task management device according to claim 10. 18. An embedded device comprising the task management device according to claim 10.