Task allocation time decision apparatus and method of deciding task allocation time

• US 20020174164A1
• Filed: 05/15/2002
• Published: 11/21/2002
• Est. Priority Date: 05/17/2001
• Status: Active Grant

• Current Assignee: Socionext Inc.
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Hayashi, Kunihiko
• Granted Patent: US 7,086,057 B2
• Time in Patent Office: Days
• US Class Current: 718/102
• CPC Class Codes: G06F 9/4887 involving deadlines, e.g. rate based, periodic

Abstract

A task allocation time decision unit inputs a period of each of the tasks and a load factor of each of the tasks with respect to execution time of all tasks from a task context memory unit, and decides the task allocation time. A task occasion frequency computation unit computes a task occasion frequency. An execution time ratio computation unit computes an execution time ratio of each task with respect to a execution time of a certain task. A schedulability condition computation unit computes a conditional expression for enabling scheduling on the basis of the period. A task allocation time decision unit computes a task allocation time for enabling scheduling from the conditional expression and the execution time ratio and outputs the resultant task allocation time to a task allocation time display unit.

Claims

1. A task allocation time decision apparatus which schedules a group of tasks generated at predetermined periods in accordance with a designated scheduling method, comprising:

an input unit which inputs constraints for activation and deadline of a plurality of tasks to be executed;

a load input unit which inputs a load for each of said tasks which is required to a processor; and

a task allocation time computation unit which computes, on the basis of said constraints and said load, allocation time of each of the tasks to said processor.

2. The task allocation time decision apparatus according to claim 1, wherein

said input unit further designates a method of scheduling tasks, and

said task allocation time computation unit produces, on the basis of said constraints, conditions for enabling scheduling with said scheduling method.

3. The task allocation time decision apparatus according to claim 1, wherein

said load input unit provides, as an input, a ratio of executing time of each task to total operating time of said processor.

4. The task allocation time decision apparatus according to claim 1, wherein

said load input unit provides, as an input, a known execution time of a part of tasks and a ratio of operating time of each of remaining tasks to the total operating time of said processor.

5. The task allocation time decision apparatus according to claim 1, wherein

said task allocation time computation unit includes:

a task occasion frequency computation unit which computes the number of tasks generated within a certain interval; and

an execution time ratio computation unit which computes, on a basis of said number of tasks generated and said load, a relationship of said allocation time between tasks.

6. The task allocation time decision apparatus according to claim 5, wherein

said task occasion frequency computation unit computes, on a basis of said period, the number of tasks generated within a time period which is a least common multiple of periods of the tasks.

7. The task allocation time decision apparatus according to claim 1 further comprising:

a task switching time input unit which inputs task switching time, wherein

said task allocation time decision unit computes said allocation time of each of the tasks with the task switching time being excluded.

8. The task allocation time decision apparatus according to claim 1 further comprising:

a whole load factor input unit which inputs a ratio of the execution time of all tasks to operating time, wherein

said task allocation time decision unit computes said allocation time of each of the tasks for enabling execution of each task only for the time corresponding to said ratio.

9. A task allocation time decision apparatus which schedules a processor with respect to tasks, comprising:

a task context memory unit which stores information necessary for deciding a allocation time for tasks;

a whole load factor input unit which inputs a ratio of time for executing all tasks to operating time of said processor;

a task switching time input unit which inputs time required for switching of tasks occurred at scheduling;

a task allocation time decision unit which decides, on the basis of the inputted information, allocation time of each of the tasks; and

a task allocation time display unit which displays said allocation time, wherein

said allocation time decision unit includes;

a task occasion frequency computation unit which computes the number of tasks generated within a certain interval;

an execution time ratio computation unit which computes a ratio of the execution time of each task to the execution time of a certain task;

a schedulability condition computation unit which computes a conditional expression of said allocation time for enabling scheduling; and

a task allocation time computation unit which computes, on the basis of the load factor of each task, said number of tasks generated and the conditional expression for enabling scheduling that serve as inputs, the allocation time of each of the tasks.

10. A method of deciding task allocation time which schedules a group of tasks generated at predetermined periods in accordance with a designated scheduling method, comprising the steps of:

inputting constraints for activation and deadline of a plurality of tasks to be executed;

inputting a load for each of said tasks which is required to a processor; and

computing, on the basis of said constraints and said load, allocation time of each of the tasks to said processor.

11. The method of deciding task allocation time according to claim 10 further comprising:

a step of designating a scheduling method of said tasks, wherein

said step of computing said task allocation time produces, on the basis of said constraints, conditions for enabling scheduling with said scheduling method.

12. The method of deciding task allocation time according to claim 10, wherein said step of inputting said load provides, as an input, a ratio of the executing time of each task to the total operating time of said processor.

13. The method of deciding task allocation time according to claim 10, wherein said step of inputting said load provides, as an input, known execution time of a part of the tasks and a ratio of the executing time of remaining tasks to the operating time of said processor.

14. The method of deciding task allocation time according to claim 10, wherein said step of computing said task allocation time further comprising the steps of:

computing the number of tasks generated within a certain interval; and

computing, on the basis of said number of tasks generated and said load, a relationship of said allocation time between the tasks.

15. The method of deciding task allocation time according to claim 14, wherein

said step of computing the number of tasks generated computes, on the basis of said period, the number of tasks generated within a certain time which is a least common multiple of the task periods.

16. The method of deciding task allocation time according to claim 10 further comprising a step of inputting task switching time, wherein

said step of deciding task allocation time further includes a step of computing the allocation time of each of the tasks with the task switching time being excluded.

17. The method of deciding task allocation time according to claim 10 further comprising:

a step of inputting a ratio of the execution time of all tasks to operating time, wherein

said step of deciding task allocation time includes a step of computes said allocation time of each of the tasks for enabling execution of each task only for the time corresponding to said ratio of said operating time.