JPS60181934A - Task priority degree controlling system - Google Patents

Abstract

PURPOSE:To execute quickly the selection of a task which is executed in the next time, also to increase a chance for executing the task, and to execute uniforminly a processing by generating a queue by connecting only the task which can be executed. CONSTITUTION:A timer mechanism initializing part 1 sets an initial value to a timer for controlling a priority degree of a task. When an interruption is generated in a timer interruption generating part 2, a timer interruption processing part 3 starts a priority degree controlling task. An execution queue managing part 4 connects the task to an execution queue, based on a task execution priority degree. In a dispatch control part 5, the task is selected in order from the execution queue whose task execution priority degree is the highest and a use right of a CPU is given. A priority degree controlling task 6 checks a queuing time with regard to the task except the execution queue of the highest task priority degree, and raises the task execution priority degree by one after a prescribed time has elapsed.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to an operating system for an information processing device, and relates to control of execution priorities of tasks.

(2) Prior art and problems When executing a job in the operating system of an information processing device, the necessary tasks are selected each time and placed in a queue, so that when it is their turn to process, the conditions for execution are met. A system is adopted in which the tasks with the highest execution priority are selected and processed in order. and,
The execution priority of tasks is different between tasks related to input/output jobs and CPU jobs, and when the relevant task uses up the time slice value (one time the CPU is allocated). It depends on whether there are any.

In such a conventional control system, tasks that are ready to be executed and tasks that are waiting for an event and cannot be executed yet are connected to the same queue, so the processing (dispatch) The drawback was that the control for selecting tasks to perform was complicated and the processing was slow. Also,
Normally, tasks for input/output jobs are given a higher execution priority than tasks for CPU jobs, so when there are many input/output jobs, the tasks for CPU jobs are given a chance to be executed. The disadvantage is that it takes a long time to obtain processing results because the frequency of processing is reduced. Historically, input/output jobs are given the same execution priority regardless of the type of input/output device, so the processing of high-speed input/output devices is delayed, which reduces the efficiency of transfer device usage. There was a drawback that it was not good.

(3) Purpose of the Invention In view of the above-mentioned drawbacks of the conventional technology, the present invention aims to provide simple control and high-speed processing, and to perform efficient processing by allocating CPU'i to executable tasks as evenly as possible. The purpose is to provide a control method that allows for

(4) Structure and object of the invention According to the present invention, in an operating system of an information processing device as described in the claims, the initial value of the execution priority of a task and the value of the execution priority after the change. and a means for managing the execution waiting time of the tasks, and form a queue by linking executable tasks according to their execution priorities, and having the highest execution priority. When there is a task that is connected to a queue other than the task queue and has exceeded a predetermined time since being connected to the queue, the execution priority of the task is changed to a higher one. This is achieved by a task priority control method characterized by:

(5) Embodiment of the Invention FIG. 1 is a diagram showing an example of the execution waiting state of a task according to the present invention, where T1 to T7 represent tasks, and (a) the initial value and (b) the initial value. indicates that task T1 is being executed.

In FIG. 1, there are five task execution priorities, and only executable tasks are linked in each queue. In addition, the initial execution priority (hereinafter referred to as static execution priority) is given a higher execution priority to tasks that use high-speed input/output devices. For example, the state changes to the state shown in FIG. 1(b).In other words, in this example, while task T1 is being executed, task T2 and task T5 have been in the execution waiting state for a certain period of time. This shows a state in which the execution priority (dynamic execution priority) of each task has increased by one.

Figure 2 is a diagram showing an example of the dynamic execution priority transition for a task whose static execution priority is 5.
The mark indicates that the task is waiting to be executed, and the diagonal line inside the egg indicates that the task has been executed (dispatched). 1 indicates that the upper limit of the execution priority of this task is 2 is shown.

FIG. 3 is a block diagram of one embodiment of the present invention, in which 1 is a timer mechanism initialization section, 2 is a timer interrupt generation section, 3 is a timer interrupt processing section, 4 is an execution wait management section, 5 is a dispatch control unit, 6 is a priority control task, and 7 is a general task.

In FIG. 3, the timer mechanism initialization unit 1 sets an initial value to a timer for task priority control (for example, it sets a timer interrupt to occur every 250 milliJ seconds).
. The timer interrupt generation unit 2 generates an interrupt when a preset time (250 milliseconds in this example) has elapsed.The timer interrupt processing unit 3 activates a priority control task and also sets an initial value to the timer. The execution queue management unit 4 connects tasks currently being executed (interrupts occurred) to the execution queue based on the static task execution priority.The dispatch control unit 5 connects tasks to the execution queue based on the static task execution priority. Tasks are selected in order from the execution queue with the highest priority and given CPU usage rights.At the same time, the dynamic task execution priority is returned to its initial value (static task execution priority).

The priority control task 6 checks the time when the execution waiting tasks other than those in the execution queue with a higher task priority are placed in the execution queue, and waits for a predetermined time (for example, 2
50 milliJ seconds), the dynamic task execution priority of the task is increased by one, and the task is reconnected to the execution queue of the corresponding execution priority. The general task 7 performs general processing (job), but if a task with a higher priority becomes waiting for execution while the task is being executed, or if the time slice value is used up, the task is switched.

Task priority control is performed using an area (control table) provided in the task control block for recording static task execution priorities, dynamic task priorities, and the time at which tasks are placed on standby for execution. Table 1 shows the triggers for changing and referencing the control table.

(6) Effects of the Invention As explained in detail above, according to the method of the present invention, only executable tasks are connected to form a queue sound, so that the next task to be executed can be quickly selected. It has the advantage of reducing time and even when there are many tasks waiting to be executed that have high execution priority.
When there is a task with a low execution priority that has been waiting for execution for a certain period of time, the execution priority is changed to a higher one, increasing the chances that the task will be executed, thereby making the processing more uniform. It has the advantage of being able to measure performance, and is highly effective because it can prevent phenomena such as the long time it takes to process CPU-based jobs and the deterioration in the usage efficiency of the transfer device connected to the high-speed input/output device f#. be.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a task waiting for execution according to the present invention, and FIG. 2 is an example of a dynamic execution priority transition for a task whose static execution priority is 5. figure,
FIG. 3 is a block diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Timer mechanism initialization unit, 2... Timer interrupt generation unit, 3... Timer interrupt processing unit, 4... Execution wait management unit, 5... Disbatch control unit, 6... Priority control tasks, 7... Patent attorney representing general tasks
Hiroshi Matsuoka Part 1 Figure 1 (a) (b) Figure 2

Claims (1)

[Claims] In the operating system of an information processing device, a means for recording the initial value of the execution priority of a task and a value of the execution priority after the change is provided in a control table, and a means for managing the execution waiting time of the task is provided. In addition to connecting tasks according to their execution priorities to form a queue,
When there is a task that is connected to a queue other than the queue of the task with the highest execution priority and has exceeded a predetermined time since being connected to the queue, the execution priority of the task is set to a high level. A task priority control method characterized in that the task priority is controlled so as to change the task priority.