JPH09198261A - Task scheduling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make discriminations between also the priority of the tasks of input/output. SOLUTION: A user can notify an operating system 1 of the priority of a task by the feeding or programming of a command. A priority fixing means 2, an input/output queue priority setting means 3 and an input/output completion time priority setting means 11 set the priority for a CPU, the processing priority on an input/output queue 9 for an input/output driver 8 and the priority at the time of the completion of the input/output of a peripheral input/output device 10 to tasks 5, 6 and 7, respectively. The tasks 5, 6 and 7 perform processings according to each priority of these. As a result, the task for which real time is required can be more preferentially processed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a task scheduling device in a time-sharing computer.

[0002]

2. Description of the Related Art Conventionally, in an operating system for a computer using a time-sharing method, one that temporarily changes the priority of a task or one that makes the priority of a task to be prioritized constant at a high priority It has been known. In these cases, the operating system normally handles the priority of the I / O wait for the peripheral I / O device according to the characteristics of the I / O device.

[0003]

In the former one of the above-mentioned conventional task scheduling apparatuses, even if the priority of a task is temporarily changed, the difference in priority with other tasks will naturally occur with the passage of time. Disappears.

Further, in the latter case, even if the priority of the task for the CPU is made constant, the priority of the input / output waiting for the peripheral input / output device is such that the tasks are processed by the first-in / first-out method. No difference,
Furthermore, when the input / output is completed, the priority of the task with respect to the CPU is temporarily increased. As a result, the priority of the task desired to be pushed low may temporarily become high, and there is a problem that it is not always possible to achieve a sufficient difference in task priority.

[0005]

A device of the present invention is a task scheduling device in a computer system having a time-sharing type task scheduling function, and the peripheral input / output is independent of the scheduling priority of the task to the CPU. It is characterized in that it has means for setting the processing priority on the input / output processing waiting queue for the device for each task from the operating system.

[0006]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention. For three tasks 5, 6 and 7, the operating system has a priority fixing means 2, an input / output queue priority setting means 3 and an input queue. By the output completion priority setting means 4,
Three types of priority are set.

The priority fixing means 2 is a means for setting priorities of the CPUs by the tasks 5, 6 and 7, and the input / output queue priority setting means 3 is a processing priority on the input / output queue 9 for the input / output driver 8. The input / output completion priority setting means 4 is a means for setting the priorities of the tasks 5, 6, and 7 when the input / output of the peripheral input / output device 10 is completed.

Task 5 is a low-priority task that performs batch processing in the background, and task 6 is a general task that is neither in the background nor in real time.
Task 7 is a high priority task that requires real-time processing.

First, when the user sets the above-mentioned respective priorities, the operating system 1 is notified by, for example, inputting a command having such contents from the console or programming. Based on this notification, the operating system 1 informs the priority fixing means 2, the input / output queue priority setting means 3 and the input / output completion priority setting means 4 of the respective priorities.

For example, the scheduling priorities of the tasks 5 and 7 are respectively set to AS and S by using the priority fixing means 2.
Set to C-S. The priority of task B is B of general tasks
The range is from -S1 to B-S2. As a result, the priority level is AS <BS-S1 <BS-2 <CS.
With this setting, the task 7 is always executed in the executable state, and the task 5 is executed only when both the task 6 and the task 7 are in the stopped state.

Next, the priority of the input / output waiting queue is determined by the task 5 using A / Q, using the input / output queue priority establishing means 3.
Task 6 is set to BQ, and task 7 is set to CQ. The high priority is AQ <B-Q <C-Q. With this setting, the input / output driver 8 sorts the queues according to the priority each time an input / output request is added to the input / output waiting queue 9.

The priority at the completion of input / output is set by the input / output completion priority setting means 4 to AI for task 5, BI for task 6, and CI for task 7. The high priority is AI <BI <CI and CS <A-
I. With this setting, if notifications of I / O completion are received at almost the same time, task 7, task 6, and task 5 are preferentially processed in this order.

The priority fixing means 2 and the input / output completion priority setting means 4 in the above-described embodiment are not always necessary, and the corresponding effect can be obtained only by the input / output queue priority setting means 3. . However, it is more effective if the input / output completion priority setting means 4 is additionally provided.

Further, when there are a plurality of general tasks that are of the same type as the task 6, that is, tasks that do not require real-time processing and are not processed in the background, input between these tasks is performed. An embodiment in which the output queue priority and the input / output completion priority are set differently can be easily considered.

[0016]

As described in detail above, according to the present invention, a task requiring real-time processing is processed with priority over other tasks including output processing to the peripheral input device.
The real-time property is further improved, and the task of executing the batch processing in the backround can be processed without significantly affecting the performance of other tasks including the input / output to / from the peripheral device.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

 1 Operating System 2 Priority Fixing Means 3 I / O Queue Priority Setting Means 4 I / O Completion Priority Setting Means 5 Tasks 6 Tasks 7 Tasks 8 I / O Drivers 9 I / O Waiting Queues 10 Peripheral I / O Devices.

Claims (3)

[Claims] 1. A task scheduling device in a computer system having a time-sharing type task scheduling function, wherein processing on an input / output processing waiting queue for a peripheral input / output device, regardless of the scheduling priority of a task for a CPU. A task scheduling device having means for setting a priority for each task from an operating system. 2. The task scheduling apparatus according to claim 1, further comprising means for setting a priority of task scheduling upon completion of input / output to / from a peripheral input / output device from the operating system. 3. The processing priority on the input / output processing waiting queue is set with a difference between general tasks that are not required to have real-time processing and are not processing to be performed in the background. Item 1. The task scheduling device according to item 1.