JP3840045B2 - Data processing method and data processing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multitasking data processing method and a data processing apparatus using the same, for example, when data such as music or video is received (streamed) in real time while receiving data such as music or video over the Internet or digital broadcasting.
[0002]
[Prior art]
When a plurality of tasks are processed by a single processing device (processor), processing is performed in a time-sharing manner. One task is 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 a task to be executed next. In the conventional method, the control program determines a task to be executed next based on the magnitude of a previously digitized value indicating the priority of each task among the executable tasks. There are several detailed decision algorithms, but typical ones are as follows. If there is one task with the highest priority among the executable tasks, it is selected. If there are two or more items having the highest priority, it is determined so that they are executed in a cyclic order.
[0003]
The numerical value indicating the priority order may be fixed or change during the execution of the task. For things that change, it is normal for the task itself to change the value. That is, according to the execution position of the program, the priority is raised when a high priority is required, and the priority is lowered when a lower priority is acceptable.
[0004]
However, when receiving data such as music or video on the Internet or digital broadcasting and playing it in real time (streaming), a program that processes streaming data such as continuously input audio data is not available. It is necessary to change the priority according to an external factor, not the execution position of the program, such as an occupation amount of a buffer in which processing data is stored. That is, when there is little unprocessed input data, the process is not urgent, but when there is a lot of unprocessed input data, if the process is not urgent, the input data overflows and data is lost. Alternatively, if processing is not performed within a certain delay, there will be a time break in the output data, and there will be a problem that sound is interrupted if it is audio data.
[0005]
[Problems to be solved by the invention]
Conventional multitask processing controls the switching of tasks to be processed based on a fixed priority order or a priority set by the program itself. The amount of data) is not suitable for streaming that requires task priorities to be determined.
[0006]
Therefore, the present invention enables multitask processing for a plurality of processing target data whose current state of input / output systems of a plurality of processing changes from moment to moment, and uses a multitask data processing method suitable for streaming and the same An object is to provide a processing apparatus.
[0007]
[Means for Solving the Problems]
The present invention is a data processing method for executing a plurality of different processes on a plurality of processing target data by multitask processing, and when switching the processing target task, input / output of the plurality of processes for each task By evaluating the current status of the system, calculating the priority of each, and determining the next processing target task based on this priority, the current status of the input / output systems of multiple processes changes from moment to moment. Data processing for a plurality of processing target data can be executed by multitask processing.
[0008]
Preferably, the priority of each task is calculated using a function for evaluating the current state of the input / output systems of the plurality of processes for each task.
[0009]
In the processing device that executes a plurality of different processes on a plurality of processing target data by multi-sk processing, the present invention evaluates the current state of the input / output system of the plurality of processes for each task when switching the processing target task. And calculating means for calculating the respective priorities, and determining the next task to be processed based on the calculated priorities, so that the current status of the input / output systems of the plurality of processes changes from moment to moment. Data processing for such a plurality of processing target data can be executed by multitask processing.
[0010]
Preferably, the priority of each task is calculated using a function for evaluating the current state of the input / output systems of the plurality of processes for each task.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
FIG. 1 conceptually shows a configuration of a main part of a data processing apparatus (hereinafter simply referred to as a processing apparatus) 1 according to the present embodiment. There are a plurality of data to be processed (here, for example, n series) (input data IDATA_1 to IDATA_n), which are respectively input to the input buffer IBF_1 to the input buffer IBF_n. These input data are, for example, a plurality of channels of audio signals and video signals. These data are often input at a substantially constant rate on a macro scale, but microscopically, it depends on the nature of the transfer side to the input buffer, and may be input in bursts. sell.
[0013]
In the processing device 1 in FIG. 1, if the processing for each input data is delayed, the input buffer overflows, so that it must be processed so as not to occur.
[0014]
The processing device 1 is configured by a single processor in terms of hardware, and a plurality of (here, for example, m) tasks (task (1) to task (m)) operate on this. To do.
[0015]
Task (1) to task (m) are processing programs for sequentially processing the data stored in the input buffers IBF_1 to IBF_n.
[0016]
The input data IDATA_1 to IDATA_n stored in the input buffers IBF_1 to IBF_n are processed by the tasks (1) to (m) and output as a plurality of (here, for example, s series) output data ODATA_1 to ODATA_s. They are stored in the output buffers OBF_1 to OBF_s accordingly. Although the output buffer may correspond to the input buffer as it is, it is assumed here that each is provided separately for the sake of simplicity of explanation. Note that m = n and / or n = s.
[0017]
Since the processing apparatus 1 of FIG. 1 is configured by a single processor, only one task is executed at the same time, and m tasks are executed in a time-divided manner. Here, a case of a processing apparatus configured with a single processor will be described as an example, but generally the same applies to a processing apparatus configured with a plurality of processors smaller than m.
[0018]
It is the control program 2 that determines time allocation to each task. Task time allocation is performed as follows. It is assumed that task (k) (an integer satisfying 1 ≦ k ≦ m) is executed at a certain time.
[0019]
The task (k) is interrupted according to certain conditions. This condition is when a certain time has elapsed from the start of the execution of task (k) in the conventional general multitask control system. In other words, the time is divided into fixed-length time slots, and tasks are assigned to each time slot.
[0020]
In the present invention, such a method can also be used. Further, as a case where this method is not used, a method in which task (k) suspends its execution can be considered. The advantage of the latter method is that it can be interrupted at its own convenience, and by interrupting at a point where processing is good, the task switching time is shortened and efficiency is improved. In other words, if the method is forcibly interrupted as in the former case, the intermediate data required when restarting later will be large, and will be saved at the time of interruption or restored at the time of restart. And spend more time. For example, when the input data is an audio signal in which the input data is compression-encoded, it is convenient to use a frame delimiter in the latter method.
[0021]
In this embodiment, even if the former task is interrupted when the former predetermined time has passed and the task is replaced, the latter task itself interrupts the processing due to a frame break, for example. Even a method of switching tasks can be applied.
[0022]
The multitask control processing operation of the control program 2 will be described below with reference to the flowchart shown in FIG.
[0023]
When the task (k) is executed by the processor of the processing device and the execution is interrupted, the processing is transferred to the control program 2. In the case of a system in which an OS (operation system) exists, the control program 2 is usually a part of the OS. The control program 2 determines a task to be executed next according to a certain condition.
[0024]
In the conventional control program, a numerical value indicating the priority is set for each task, and among the executable tasks, the task having the largest numerical value is selected as the task to be executed next. Here, in the case of the processing system as shown in FIG. 1, in the processing system as shown in FIG. 1, in the input / output system of processing corresponding to each task, the input buffer is not empty and the corresponding output buffer is not full. is there.
[0025]
However, in the processing system shown in FIG. 1, it is not desirable to prioritize each task in advance or set its own priority when executing the task. This is because the priority should be that the input buffer does not overflow and the output buffer does not become empty. These conditions change from moment to moment even when the task is not running. Because. In other words, the numerical value representing the priority needs to be changed every moment.
[0026]
In the present invention, in order to realize the priority that changes from moment to moment, the status functions st_1 to st_m are associated with each of the tasks (1) to (m), and the task to be executed next by the control program 2 is determined. At the time of selection (when the task is switched), that is, after the task that has been executed is interrupted, the status functions st_1 to st_m corresponding to the tasks (1) to (m) are called (step S1). ) By using each status function, for example, the result of calculating the priority by the calculation method described later is acquired (step S2).
[0027]
The control program selects a task with the highest priority as a task to be executed next from the value obtained from each status function, that is, the priority of each task. Here, the selected task is defined as task (k) (step S3). The control program causes the processor to execute the selected task (k) as the next processing target when switching tasks.
[0028]
Each of the status functions st_1 to st_m is configured to evaluate the current state of the input / output system of the task corresponding to them and return a priority corresponding thereto. It is also possible to return information about whether each task can be executed or not. Here, execution is impossible, for example, when the input buffer occupation amount is empty or the output buffer occupation amount is full.
[0029]
In step S3, after calling all these status functions, the control program 2 selects the task with the highest priority among the tasks that can be executed as the task to be executed next.
[0030]
Next, a method for calculating the priority of the status function will be described here with two examples. Note that the method of calculating the priority of the status function is not limited to the method described here.
[0031]
As a first calculation method, each status function examines the occupation amount of the input buffer corresponding to the status function, and converts the occupation amount into priority according to a certain rule. A certain rule is, for example, estimating the time to overflow from the occupation amount and the rate of input data expected in advance. The shorter the time, the higher the priority, and the longer the time, the lower the priority. Convert by such a table.
[0032]
As a second calculation method, each status function examines a time stamp of data that has been processed by a task corresponding to the status function, and converts the difference between the time and the actual time into a priority and returns it. In this case, it is a condition that all the input data IDATA_1 to IDATA_n is data having a time stamp. Further, it is assumed that the processing device 1 is provided with a clock or a counter indicating the current time. In this example, the highest priority is given to the one with the largest delay with respect to real time.
[0033]
As described above, according to the above embodiment, the status function for evaluating the current state of the input / output system of the corresponding process is associated with each task, and the control program 2 switches the task to be processed. By using the value returned from the status function of each task as the priority of the task, by determining the next task to be processed, a plurality of processes in which the current status of the input / output systems of multiple processes changes from moment to moment It is possible to execute data processing for the processing target data in multitask processing. For example, when streaming, processing is performed in time for a predetermined time, the input buffer overflows, and output is interrupted. There is no longer to do.
[0034]
In addition, this invention is not limited to the said embodiment, In the implementation stage, it can change variously in the range which does not deviate from the summary. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriate combinations of a plurality of disclosed constituent requirements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem (at least one of them) described in the column of the problem to be solved by the invention can be solved, and the column of the effect of the invention If at least one of the effects described in (1) is obtained, a configuration from which this configuration requirement is deleted can be extracted as an invention.
[0035]
【The invention's effect】
As described above, according to the present invention, it becomes possible to execute data processing for a plurality of processing target data such that the current state of input / output systems of a plurality of processing changes from time to time in multitask processing, Multitask data processing suitable for streaming can be realized.
[Brief description of the drawings]
FIG. 1 is a diagram conceptually showing a configuration of a main part of a data processing apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining a multitask control processing operation of a control program.
[Explanation of symbols]
IDATA_1 to IDATA_n: input data IBF_1 to IBF_n ... input buffer St_1 to St_m ... status functions ODATA_1 to ODATA_s ... output data OBF_1 to OBF_s ... output buffer

Claims (4)

A processor;
A plurality of input buffers for storing input data to be input at a predetermined rate;
Control means for performing control to execute a plurality of tasks for processing data stored in the plurality of input buffers in a time-sharing manner by the processor;
A plurality of output buffers for storing output data output as a result of processing by each task executed by the processor;
A data processing method in a data processing apparatus comprising:
When execution of one of the plurality of tasks is interrupted by the processor, the input buffer is determined based on the amount of data stored in each input buffer by the control means and the rate of input data input to the input buffer. A calculation step for calculating the time to overflow,
The control means determines a higher priority for the task of processing data stored in each input buffer as the time calculated for the input buffer is shorter ;
A selection step in which the control means selects a task having the highest priority among the plurality of tasks as a next processing target of the processor;
The control means causing the processor to execute a selected task;
A data processing method. In the selection step, among the plurality of tasks, an input buffer for storing input data processed by the task is not empty, and an output buffer for storing output data output as a result of processing by the task is not full from among the tasks, the data processing method according to claim 1, wherein the selecting said next processing target task. A processor;
A plurality of input buffers for storing input data to be input at a predetermined rate;
Control means for performing control to execute a plurality of tasks for processing data stored in the plurality of input buffers in a time-sharing manner by the processor;
A plurality of output buffers for storing output data output as a result of processing by each task executed by the processor;
In a data processing apparatus comprising:
The control means includes
When the execution of one of the plurality of tasks is interrupted by the processor, the amount of data stored in each input buffer and the rate of input data input to the input buffer until the input buffer overflows. A means of calculating time;
Means for determining a higher priority for the task of processing the data stored in each input buffer as the time calculated for the input buffer is shorter ;
Selecting means for selecting a task having the highest priority among the plurality of tasks as a next processing target of the processor;
A data processing apparatus comprising: causing the processor to execute a selected task. The selection means is that the input buffer for storing input data processed by the task is not empty and the output buffer for storing output data output as a result of processing by the task is not full among the plurality of tasks. 4. The data processing apparatus according to claim 3 , wherein the task to be processed next is selected from the tasks.

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