JP2002189604A - Multi-tack processing method and processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-task processing method capable of multi-task processing without impairing response to a command and a processor using the same. SOLUTION: When switching takes place between tasks to be processed in order to execute a plurality of different processes by multi-task processing, the next task to be processed is determined based on a plurality of criteria on the respective tasks. At least one of the plurality of tasks is a task that receives a receivable command previously determined for processing the task and processes the command, that this task has received the command is set as one of the plurality of criteria, and the task having received the command is preferentially determined as the next task to be processed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multitask processing method and a processing device using the same.

[0002]

2. Description of the Related Art When a plurality of tasks are processed by a single processing device (processor), processing is performed in a time-division manner. One task is being executed at a certain time, and when the execution of this task is interrupted, control is transferred to the control program, and the control program determines the next task to be executed. In the conventional method, the control program determines the next task to be executed based on the value of a numerical value that indicates the priority of each task among the executable tasks. Although there are several detailed determination algorithms, typical ones are as follows. If one of the tasks that can be executed has the highest priority,
It is selected. If there are two or more of the highest priorities, it is determined that they are executed cyclically in order.

[0003] Numerical values indicating priorities may be fixed or variable during execution of a task. For things that change, it is normal for the task itself to change the value.
In other words, according to the execution position of the program, the priority is raised when a higher priority is required, and the priority is lowered when a lower priority is better.

However, when data such as music or video is received and reproduced in real time (streaming) over the Internet or digital broadcasting, a program for processing streaming data such as audio data that is continuously input is required. Conventionally, when a task receives an external command such as a process stop command (“STOP” command) or a command to change a parameter such as a bit rate during execution, conventionally, when determining the priority, Since the presence / absence is not considered at all, there is a problem that the execution of the task receiving the command is delayed, and as a result, the response of the command is deteriorated.

[0005]

In the conventional multitask processing, switching of a task to be processed is controlled based on a fixed priority or a priority set by a program itself. When the command is received, the task has a low priority, the command cannot be executed, and the response of the command is poor.

In view of the above problems, an object of the present invention is to provide a multitask processing method that enables multitask processing without impairing command responsiveness, and a processing apparatus using the same.

[0007]

According to the present invention, a plurality of different processes are executed by a multitask process, and when a task to be processed is switched, a next task to be processed is determined based on a plurality of criteria. At least one of the plurality of tasks is a task that receives a predetermined command in the processing of the task and processes the command, and the task receives the command. Is set as one of the plurality of criteria, and the task that has received the command is preferentially determined as the next processing target task, thereby enabling multitask processing without impairing the responsiveness of the command. .

Preferably, the priority of each of the tasks that have received the command is calculated based on another one of the plurality of criteria, and the next task to be processed is determined based on the calculated priority. To be determined.

Preferably, priorities are calculated for all tasks based on other of the plurality of criteria, ignoring the presence / absence of a task accepting the command. When there is a plurality of tasks having the highest calculated priority, the task that has received the command among the tasks is determined as a task to be processed next.

Further, the present invention executes a plurality of different processes in a multitask process and determines the next task to be processed based on a plurality of criteria when switching the tasks to be processed. , At least one of the plurality of tasks is a task that receives a predetermined command in the processing of the task and processes the command. Calculating the priority of each task using at least one of the command types as one of the plurality of criteria;
By determining the next processing target task based on this priority, multitask processing can be performed without impairing the responsiveness of the command.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 conceptually shows a configuration of a main part of a data processing device (hereinafter simply referred to as a processing device) 1 according to the present embodiment. There are a plurality of data to be processed (here, for example, n series) (input data IDATA_1
~ IDATA_n), each of which has an input buffer I
BF_1 to BF_1 are input to the input buffer IBF_n. These input data are, for example, audio signals and video signals of a plurality of channels. These data are often input at a substantially constant rate in macro terms, but microscopically depend on the nature of the transfer to the input buffer, and may be input in bursts. sell.

In the processing device 1 shown in FIG. 1, if the processing for each input data is delayed, the input buffer overflows. Therefore, the processing must be performed so as not to occur.

The processing apparatus 1 is composed of a single processor in terms of hardware, on which a plurality (here, for example, m) of tasks (tasks (1) to (m)) operate. It shall be.

Tasks (1) to (m) are processing programs for sequentially processing data stored in the input buffers IBF_1 to IBF_n.

Input data IDATA_1 to IDATA_ stored in input buffers IBF_1 to IBF_n
n is processed by tasks (1) to (m), and a plurality (here, for example, s series) of output data ODATA_
1 to ODATA_s and stored in output buffers OBF_1 to OBF_s, respectively. Although the output buffer may correspond to the input buffer as it is, it is assumed here that they are separately provided for the sake of simplicity. Note that m = n and / or n =
It may be s.

Further, interfaces (command boxes CB_1 to CB_n in FIG. 1) are connected to each of the tasks (1) to (m) to receive external commands COM_1 to COM_n. Here, command boxes CB_1 to CB_n are connected to all tasks (1) to (m).
It is sufficient that a command box is connected to each task.

The command boxes CB_1 to CB_n are:
For example, FIFO (First In First Out) memory,
It may be a RAM.

The commands input (written) to each of the command boxes CB_1 to CB_n during the execution of the multitask process include commands input by a user and commands input from an application currently being executed. However, specifically, for example, a command to stop processing (“STOP” command), a command to change a parameter such as a bit rate, or a command that requires real-time processing for adjusting output data (for example, when output data is voice Command to increase or decrease the volume).

Since the processing device 1 of FIG. 1 is constituted by a single processor, only one task is executed at a time, and m tasks are executed in a time-division manner. Here, a case of a processing device composed of a single processor will be described as an example, but the same applies to a processing device composed of a plurality of processors less than m in general.

The time allocation for each task is determined by
This is the control program 2. Task time allocation is performed as follows. Task (k) at a certain time (1 ≦ k
≦ m).

The processing of task (k) is interrupted according to certain conditions. This condition is when a certain time has elapsed after the execution of the task (k) has started in the conventional general multitask control method. That is, the time is divided into fixed-length time slots, and a task is assigned to each time slot.

In the present invention, such a system can be used. As a case where this method is not used, a method in which the task (k) suspends execution by itself can be considered. The advantage of the latter method is that the interruption can be performed at its own convenience. Therefore, by interrupting where the break is good in processing, the time at the time of task switching is shortened and the efficiency is high. In other words, conversely, in the former method in which forced interruption is performed, the intermediate data required when resuming later becomes large, and it is necessary to save them at the time of interruption,
You'll spend more time restoring them when you resume. For example, when the input data is a compression-coded audio signal, the processing break in the latter method is preferably a frame break.

In this embodiment, even if the former is a method of switching the task by interrupting the processing of the task when the predetermined time has elapsed, the latter task itself interrupts the processing, for example, at the break of a frame. Even when the task is switched, the method can be applied.

The multitask control processing operation of the control program 2 will be described below with reference to the flowcharts shown in FIGS.

The task (k) is executed by the processor of the processing device, and when the execution is interrupted, the processing is shifted to the control program 2. When the control program 2 is a system in which an OS (operation system) exists,
Usually, it is part of the OS. The control program 2 determines the next task to be executed based on a plurality of criteria such as the existence of a command and the current state of the input / output system.

In the conventional control program, a numerical value indicating the priority is set for each task, and among the executable tasks, the one having the highest numerical value is selected as the task to be executed next. . Here, "executable" means that, in the case of the processing system as shown in FIG. 1, the input buffer is not empty and the corresponding output buffer is not full in the input / output system of the processing corresponding to each task. is there.

However, in the processing system shown in FIG. 1, it is not desirable to prioritize each task in advance or to set its own priority when executing a task. Because the priority here is that the input buffer does not overflow and the output buffer does not become empty, and these conditions change every moment even when the task is not running. Because. That is, it is necessary that the numerical value representing the priority change every moment.

Therefore, in FIG. 1, each task (1) to task (m) is performed in order to realize a priority that changes every moment.
Are respectively associated with the status functions st_1 to st_m, and when the control program 2 selects the task to be executed next, the status functions st_1 to st_m corresponding to the respective tasks (1) to task (m) are called. For example, a result of calculating a priority based on the current state of the input / output system by a calculation method described later is acquired by each status function.

In the multitasking process in streaming, a command may be received from the outside, and in such a processing system as shown in FIG. 1, the conventional system is not preferable. This is because, when there is a task in which a command is written in the command box and a task in which no command is written, the presence or absence of the command is not considered at all when determining the priority. Therefore, there is a possibility that a response to a command input from outside is delayed.

Therefore, when deciding the priority, the existence of a command in the command box corresponding to each task will be considered. How to reflect the presence of the command in the task priority depends on the configuration of the processing device 1, and there are countless methods. Since it is impossible to list all of them individually, only some of them will be described. Note that the methods described below can be used in appropriate combinations.

First, referring to FIG.
The multitask control process (process A) will be described.

Process A shown in FIG. 2 is a method in which the presence of a command as a criterion for determining a task to be processed next is more important than other criterions.
That is, the control program 2 checks whether or not a command has been written in the command box of each task (whether or not a command has been received) (Step S).
1). If there are a plurality of tasks in which commands are written in the command box, the priority of each of the plurality of tasks is calculated based on criteria other than the commands (step S2). The control program selects the task with the highest priority as the task to be executed next from the priorities of the plurality of tasks. Here, the selected task is set as a task (k) (step S4). When the control program switches tasks, the control program
The selected task (k) is executed as the next processing target. If there is one task in which a command is written in the command box, the task is selected as the task (k) to be executed next (step S4).
If there is no task in which the command is written in the command box, the priority is calculated for all tasks, and the task with the highest calculated priority is selected as the task (k) to be executed next (step S4).

In steps S2 and S3,
A priority assigned to each task in advance or a priority set by itself when executing the task may be used. Preferably, the current state of the input / output system of the input buffers IBF_1 to IBF_n and the output buffers OBF_1 to OBF_s is used. As a criterion, it is desirable to calculate the priority each time the task is switched, provided that the input buffer does not overflow and the output buffer does not become empty. Here, an example of a method of calculating the priority for that purpose will be described. That is, in order to realize a priority that changes every moment, status functions St_1 to St_m are associated with each of the tasks (1) to (m), and the control program 2 executes the tasks (1) to ( m), the status functions St_1 to St_m corresponding to
For example, a result of calculating the priority by a calculation method described later is acquired by each status function.

Each of the status functions St_1 to St_m is
Evaluate the current state of the input / output system of the task corresponding to them,
It is designed to return the corresponding priority. It is also possible to return information on whether each task is executable or not. Here, execution is not possible when, for example, the input buffer occupancy is empty or the output buffer occupancy is full.

Next, a method of calculating the priority of the status function will be described with reference to two examples. It should be noted that the method of calculating the priority of the status function is not limited to only those listed here.

As a first calculation method, each status function checks the occupancy of the input buffer corresponding to the status function, and converts the occupancy into priority according to a certain rule. A certain rule is, for example, estimating the time until overflow from the occupation amount and the rate of input data that is expected in advance, the shorter the time, the higher the priority, and the longer the time, the lower the priority Is converted by such a table.

As a second calculation method, each status function checks the time stamp of data for which the corresponding task has completed processing, and converts the difference between the time and the actual time into a priority. Return. In this case, the condition is that all of the input data IDATA_1 to IDATA_n are data having a time stamp. It is also assumed that the processing device 1 is provided with a clock or counter indicating the current time. In this example, the one with the largest delay with respect to real time is given the highest priority.

Next, referring to FIG.
The multitask control process (process B) will be described.

Processing B shown in FIG. 3 is a method in which the presence of a command as a criterion for determining a task to be processed next is lower in importance than other criterion.
That is, first, the control program 2 ignores the presence / absence of a command for each task and calculates the priority of each task based on the other determination criteria described above (step S11). The method of calculating the priority may be the same as described above. Only when there are a plurality of tasks with the highest priority among the calculated priorities of the tasks (step S12), it is determined whether or not a command is written in each command box for the plurality of tasks. Then, the task receiving the command is selected as the task (k) to be processed next (step S13).

In step S13, if there are a plurality of tasks receiving commands among the tasks having high priority, the task (k) having the larger number of commands may be selected as the task (k). Good. Step S
If there is only one task with the highest priority at 12,
The process directly proceeds to step S14, and the task is set as a task (k).

Next, referring to FIG.
The multitask control process (process C) will be described.

Process C shown in FIG. 4 is a method in which the presence of a command is added as a point to the priority itself of each task, and a priority reflecting the presence of the command is used. That is, when a command is written in the command box, a predetermined point corresponding to the priority is determined in advance for each command. First, the control program 2
The priority of each task is calculated, ignoring the presence or absence of a command for each task (step S21). The method of calculating the priority may be the same as described above. Then, it is checked whether or not a command is written in each command box of each task, and if there is a task receiving the command, the above-mentioned task is described according to the number of commands written in the priority of the task. The predetermined points are added (step S22). Alternatively, when one or more commands are written, a predetermined point may be added to the priority regardless of the number.

The task with the highest priority is selected as the task (k) to be executed next (step S23).

In the above process C, a predetermined point is uniformly added to one command written in the command box regardless of the type of command. However, different points are added depending on the type of command. Points may be added to the priority. That is, the degree of urgency may differ depending on the type of command. For example, commands that require real-time properties (for example, commands that directly affect output data)
It is necessary to respond quickly, but the other is that urgency is not required and the response should be made when the CPU is idle. In this case, depending on the type of command,
Predetermined points according to the urgency of the command,
For example, a command table as shown in FIG. 5 is set in advance. The control program 2 corresponds to step S22 in FIG.
When adding a point to the priority, a point value corresponding to the type of the command is read from the command table shown in FIG. 5 and is added to the priority. When a plurality of commands are written in the command box, a point value corresponding to the type of each command may be read from the command table and added to the priority.

As described above, according to the above embodiment, the control program 2 determines that a task has received a command by one of a plurality of criteria for determining the next task to be processed. The task that has received the command is preferentially determined as the task to be processed next (for example, for each task that has received the command, the priority is calculated based on another criterion, and the calculated The priority is determined as the next processing target task based on the priority, or the priority is calculated for all tasks based on other criteria, ignoring the presence or absence of a task that is accepting a command. Only when there is more than one task with the highest priority, the task that is accepting the command among the tasks Determining a click.), To allow multitasking without impairing the response of the command.
For example, even when a command is input from the outside during the multitask processing in the streaming processing, the multitask processing can be performed without impairing the responsiveness of the command.

Further, at least one of the presence / absence of a command accepted by the task, the number of commands, and the type of command is set as one of a plurality of criteria for calculating the priority of each task. By calculating the priority and determining the next task to be processed based on the priority, multitask processing can be performed without impairing the responsiveness of the command. For example, even when a command is input from the outside during the multitask processing in the streaming processing, the multitask processing can be performed without impairing the responsiveness of the command.

Further, when determining the next task to be processed, as one of the other criteria, the current state of the input / output system of the processing of each task is taken into consideration, so that the input / output It becomes possible to execute data processing on a plurality of processing target data such that the current state changes moment by moment by multitask processing, for example, in the case of streaming, processing is performed in time for a predetermined time,
The input buffer does not overflow or the output is not interrupted.

The present invention is not limited to the above-described embodiment, and can be variously modified in the practical stage without departing from the gist thereof. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of a plurality of disclosed configuration requirements. For example, even if some components are deleted from all the components shown in the embodiments, (at least one of) the problems described in the column of the problem to be solved by the invention can be solved, and the effect of the invention can be solved. If at least one of the effects described in (1) is obtained, a configuration from which this component is deleted can be extracted as an invention.

The method of the present invention described in the embodiment of the present invention can be executed by a computer as a program, such as a magnetic disk (floppy (registered trademark) disk, hard disk, etc.), an optical disk (C
D-ROMs, DVDs, etc.) and storage media such as semiconductor memories for distribution.

[0051]

As described above, according to the present invention,
Multitask processing can be performed without impairing command responsiveness.

[Brief description of the drawings]

FIG. 1 is a diagram conceptually showing a configuration of a main part of a processing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the multitask control processing (processing A) operation of the control program.

FIG. 3 is a flowchart for explaining a multitask control processing (processing B) operation of the control program.

FIG. 4 is a flowchart for explaining a multitask control processing (processing C) operation of the control program.

FIG. 5 is a diagram showing an example of a command table.

[Explanation of symbols]

 IDATA_1 to IDATA_n ... input data IBF_1 to IBF_n ... input buffers St_1 to St_m ... status functions ODATA_1 to ODATA_s ... output data OBF_1 to OBF_s ... output buffers COM_1 to COM_n ... commands CB_1 to CB_n ... command boxes

Claims (6)

[Claims] 1. A multitask processing method for executing a plurality of different processes in a multitask process and determining a next process task based on a plurality of criteria when switching a task to be processed. In at least one of the plurality of tasks, a task that receives a predetermined command in the processing of the task and processes the command, and that the task has received the command, Wherein the task that has received the command is preferentially determined as the next processing target task. 2. A task receiving the command calculates a priority based on another one of the plurality of criteria, and determines a task to be processed next based on the calculated priority. 2. The multitask processing method according to claim 1, wherein the determination is performed. 3. Ignoring the presence or absence of a task that is accepting the command, first calculate the priority of each task based on another of the plurality of criteria, and calculate the priority. 2. The multitask processing method according to claim 1, wherein when there are a plurality of tasks having the highest priority, the task that has received the command among the plurality of tasks is determined as a task to be processed next. 4. A multitask processing method, wherein a plurality of different processes are executed in a multitask process, and a next task to be processed is determined based on a plurality of criteria when switching a task to be processed. , At least one of the plurality of tasks is a task that receives a predetermined command in the processing of the task and processes the command. The task includes the presence or absence of the command and the number of commands. And calculating the priority of each task using at least one of the command types as one of the plurality of criteria, and determining the next task to be processed based on the calculated priority. A multitask processing method. 5. A processing device for executing a plurality of different processes in a multitask process, comprising: a determination unit for determining a next process target task based on a plurality of criteria when switching a process target task; At least one of the plurality of tasks is a task that receives a predetermined command in the processing of the task and processes the command, and the determining unit determines that the task receives the command. Is one of the plurality of criteria, and the task that has received the command is preferentially determined as the task to be processed next. 6. A processing device for executing a plurality of different processes in a multi-task process, wherein when switching a task to be processed, calculating means for calculating respective priorities based on a plurality of criteria, Determining means for determining a next processing target task based on the calculated priority, wherein at least one of the plurality of tasks receives a command predetermined in the processing of the task, and Wherein the calculating unit determines at least one of the presence or absence of a command, the number of commands, and the type of command accepted by the task as one of the plurality of determination criteria. A processing device for calculating the priority of each.