JP2005190238A - Real time control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a real time control system capable of preempting a non-real time task without keeping a real time task waiting. <P>SOLUTION: In the system where the real time task requiring real time processing and the non-real time task not requiring the real time processing are mixed, a real time task start interruption is processed when the interruption is inputted during the execution of the non-real time task (step 101), whether the non-real time task is executing processing in a preempt prohibited section or not is determined (step 102), and when determining that the non-real time task is executing processing in the preempt inhibition section, processing executed by the non-real time task in the preempt prohibited section is canceled and the non-real time task is preempted by the real time task (step 104). When the preempted non-real time task obtains execution right again in a step 105, the non-real time task tries the processing again from the head of the preempt prohibited section. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a real-time control method for an operating system built in an embedded system or device.

  The OS (operating system) of the computer is an OS that does not place importance on real-time performance such as a personal computer (hereinafter referred to as a general-purpose OS) and a real-time OS that places importance on real-time performance installed in an embedded system such as an automobile or home appliance. Broadly divided. However, the scale of software has also increased in the field of embedded systems, and general-purpose OSs such as Linux are being used in embedded systems in order to use their software assets. In such an embedded system, processing that does not require real-time property and processing that requires real-time property are mixed. For this reason, it is necessary to reduce the influence of delaying a process requiring real-time property by a process not requiring real-time property as much as possible.

In the conventional general-purpose OS, a long interrupt prohibition section exists, or another task is prohibited from being preempted while a system call is being executed. In such an OS, the start of real-time processing is waited until the end of the interrupt-prohibited section, or is waited until the end of system call processing. In order to deal with a long interrupt prohibition section, for example, there is a method of accepting an interrupt of real-time processing even in the interrupt prohibition section (see, for example, Patent Document 1). In addition, there is a preemption kernel that allows other tasks to be preempted even during execution of a system call in order to reduce the preemption prohibition section of the task (see, for example, Non-Patent Document 1).
Japanese Patent Laid-Open No. 11-96022 Tomonori Shindo, Daiki Ito “Next-generation Linux is in our hands” Nikkei Electronics 2003.6.23 P.118-P.119

  However, in the above-described preemption kernel, there are preemption prohibition sections in which other tasks can be preempted even during execution of the system call but still cannot be preempted. If the preemption prohibition period is long, the real time task cannot be preempted, and the real time task may not be able to complete processing within the required time.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a real-time control method that can preempt a non-real-time task without waiting for the real-time task.

In order to achieve the above-described object, the real-time control method according to claim 1 of the present invention is a real-time control method in a system in which a real-time task requiring real-time processing and a non-real-time task not requiring real-time processing are mixed. ,
When executing a non-real-time task, processing a real-time task wake-up request interrupt, determining whether the non-real-time task being executed is executing a preemption prohibition interval, and determining that a preemption prohibition interval is being executed , A step for setting a flag for recording that the preemption is performed by the real time task in the preemption prohibition section, a step for the real time task to preempt execution, and the execution of the preempted non-real time task when the real time task ends. Re-acquiring, determining whether or not the flag is set, and determining that the flag is set are steps for resuming the processing of the non-real-time task from the beginning of the preemption prohibition interval. And flop, when the flag is judged not set, characterized in that a resuming from where the preempted processing non-real-time tasks.

The real-time control method according to claim 2 is a real-time control method in a system in which a real-time task that requires real-time processing and a non-real-time task that does not require real-time processing coexist.
As preemption prohibition section processing, it comprises a step of determining whether an execution task is a real-time task or a non-realtime task, and a step of storing the resource state protected in the preemption prohibition section processing when the execution task is determined to be a non-realtime task,
When executing a non-real-time task, processing a real-time task wake-up request interrupt, determining whether the non-real-time task being executed is executing a preemption prohibition interval, and determining that a preemption prohibition interval is being executed , Setting a flag that records that the preemption is performed by the real-time task in the preemption prohibition section, restoring the saved resource state, pre-executing the real-time task, and when the real-time task ends. The preempted non-real-time task re-acquires execution rights, the step of determining whether the flag is set, and the determination of the flag being set, the processing of the non-real-time task The pre The head resuming from Nputo inhibition interval, when the flag is determined not to be set, characterized by comprising a resuming from where the preempted processing non-real-time tasks.

  Furthermore, the real-time control method according to claim 3 is the real-time control method according to claim 1 or claim 2, wherein the execution task is determined as a real-time task or a non-real-time task as processing in the preemption prohibition section; When the execution task is determined to be a non-real-time task, it includes a step for determining whether or not the processing for the preemption prohibition section is reduced, and a step for prohibiting the preemption for the realtime task when it is determined that the processing for the preemption prohibition section is low. It is characterized by that.

The real-time control method according to claim 4 is a real-time control method in a system in which a real-time task that requires real-time processing and a non-real-time task that does not require real-time processing coexist.
As preemption prohibition section processing, determining whether an execution task is a real-time task or a non-real-time task; determining an execution task as a real-time task; allocating a first resource; determining an execution task as a non-real-time task; Allocating a second resource,
While executing a non-real-time task, processing a real-time task wake-up request interrupt, a step in which the real-time task preempts execution, and when the real-time task ends, the pre-empted non-real-time task reacquires execution rights. And resuming execution from the location where the non-real-time task is preempted using the allocated second resource.

Furthermore, the real-time control method according to claim 5 is a real-time control method in a system in which a real-time task requiring real-time processing and a non-real-time task not requiring real-time processing are mixed.
In the run queue processing for managing executable tasks, a step of determining whether a task is a real-time task or a non-real-time task, a step of using a first run queue when a task is determined to be a real-time task, and a task being a non-real-time task The second run queue is used, the real-time task wake-up request interrupt is processed while the second run queue is used, the real-time task preempts execution, and the real-time task ends. And a step of restarting the preempted process.

  The real-time control method of the present invention has the above steps, and since a real-time task can be preempted even in a section where preemption is prohibited in the conventional preemption kernel, the real-time task is waited for processing of other non-real-time tasks. The process can be completed within the required time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The real-time control method of the present invention is a system in which a real-time task that requires real-time processing and a non-real-time task that does not require real-time processing, such as digital TV and DVD player, which requires real-time properties such as video processing and audio processing. It is a computer control method used for home appliances etc. in which non-real-time tasks that do not require real-time properties such as user interface processing that accepts instructions from users and tasks, and the real-time control method in such a system is described below. explain.
[Embodiment 1]
Embodiment 1 of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a flowchart showing a processing procedure when a real-time task wake-up request interrupt occurs during execution of a non-real-time task.

  When a real-time task wake-up request interrupt occurs during execution of a non-real-time task, this real-time task wake-up request interrupt is processed (step 101), and it is determined whether or not the non-real-time task being executed is executing a preemption prohibition section ( Step 102). The preemption prohibition section is set to protect an OS resource that requires exclusive control. During execution of this section, the conventionally executed task is not preempted by another task.

  If it is determined that the non-real-time task being executed is executing the preemption prohibited section, a flag is set (step 103). This flag records that preemption is performed by the real-time task in the preemption prohibition section, and is used for reference in step 106 described later. If it is determined in step 102 that it is not a preemption prohibition section, this flag is not set.

  After step 103, or when it is determined that the non-real-time task being executed in step 102 is not executing the preemption prohibited section, the real-time task preempts execution (step 104). During execution of the real-time task, execution of the preempted non-real-time task is interrupted.

  When the execution of the real-time task is finished, the preempted non-real-time task re-acquires the execution right (step 105). It is determined whether or not a flag is set (step 106).

  If it is determined that the flag is set, it is preempted by the real-time task in the preemption prohibition section, so the processing of the non-real time task is restarted from the beginning of the preemption prohibition section (step 107).

If it is determined in step 106 that the flag is not set, the processing of the non-real time task is resumed from the preempted location (step 108).
FIG. 2 is a diagram showing a conventional OS and each task switch in the first embodiment when a real-time task wake-up request is generated in order to show the effect of the first embodiment. FIG. 2A shows a conventional OS task switch, and FIG. 2B shows the first embodiment.

  As shown in FIG. 2A, in the conventional OS, when a real-time task wake-up request is generated in a preemption prohibited section, the wake-up of the real-time task is waited until the non-real-time task finishes the processing of the preemption prohibited section.

  In the first embodiment, as shown in FIG. 2B, if there is a real-time task wake-up request, the real-time task is woken up immediately. In this way, if a non-real-time task wake-up request interrupt occurs during execution of a non-real-time task, and it is determined that the non-real-time task is executing a preemption-prohibited section at this time, the processing performed by the non-real-time task in the pre-emption prohibited section Is discarded, and the real-time task is preempted. When the preempted non-real-time task obtains the right to execute again in step 105, the processing is restarted from the beginning of the preemption prohibited section in step 107.

  As described above, even if a non-real-time task is executing a preemption prohibition interval, the real-time task is not waited until the non-real-time task finishes the preemption prohibition interval. (Real-time tasks can preempt execution of non-real-time tasks in any case), and real-time properties can be ensured.

Also, if the non-real-time task confirms the flag, it resumes from the beginning of the preemption prohibited section, and is executed in the resource state before the start of the preemption prohibited section, so even if the resource is rewritten by the real-time task, Operation can be guaranteed.
[Embodiment 2]
A second embodiment of the present invention will be described with reference to FIG.

  FIG. 3A shows a process executed by a task in a preemption prohibited section, and FIG. 3B shows a process procedure when a real-time task wake-up request interrupt occurs during execution of a non-real-time task.

  As shown in FIG. 3A, as preemption prohibition interval processing, it is determined whether or not the execution task is a non-real-time task at the entrance of the preemption prohibition interval (step 301). The state of the resource protected in the prohibited section is saved (step 302).

  Further, as shown in FIG. 3B, when a real-time task request interrupt occurs during execution of a non-real-time task, this real-time task wake-up request interrupt is processed (step 303), and the non-real-time task is executing a preemption prohibited section. If it is determined whether or not the preemption prohibition section is being executed, a flag is set (step 305), and the resource state saved in step 302 is restored (step 306). This flag records that preemption has been performed by the real-time task in the preemption prohibition section. If it is determined in step 304 that the preemption prohibition section is not being executed, nothing is done.

  Thereafter, the real-time task preempts execution (step 307). During execution of the real-time task, execution of the preempted non-real-time task is interrupted. When the execution of the real-time task ends, the preempted non-real-time task re-acquires the execution right (step 308) and resumes execution.

  Next, it is determined whether or not the flag is set (step 309). If it is determined that the flag is set, it is preempted by the real-time task in the preemption prohibition section. The process restarts from the beginning of the preemption prohibited section (step 310). If it is determined that the flag is not set, the processing of the non-real time task is resumed from the preempted location (step 311).

  The difference between the second embodiment and the first embodiment is that the resource state at the start of the preemption prohibition section is saved in step 302 and the resource state is restored in step 306. When a resource is rewritten by a non-real-time task during the preemption prohibition interval, the operation cannot be guaranteed if the real-time task preempts and accesses the same resource during rewriting. Therefore, in order to prevent a problem in operation even when a real-time task is accessed, the resource state at the start of the preemption prohibited section is restored in step 306. If there is a request to wake up a real-time task after the non-real-time task ends the preemption prohibition section, it is not necessary to restore the saved resource state.

  As described above, a real-time task can preempt execution of a non-real-time task at any time, and even if the resource protected by the non-real-time task is changed in the pre-emption prohibited section, it is pre-empted during the pre-emption prohibited section. The real-time task can use the resource and guarantee the operation without causing any trouble in the system.

Note that Embodiment 1 may be used if the non-real-time task only refers to the preemption prohibited section without changing the resource state.
[Embodiment 3]
A third embodiment of the present invention will be described with reference to FIG.

  FIG. 4A shows the execution of a non-real-time task when there is no real-time task wake-up request. A bold line indicates a preemption prohibited section. FIG. 4B shows a state of execution when a real-time task wake-up request is generated in the preemption prohibited section in the non-real-time task having the same processing contents in the first or second embodiment. Even if there is only a small amount of processing in the preemption prohibition section, if there is a real-time task wake-up request, the real-time task is preempted immediately, and the non-real-time task restarts processing from the beginning after re-acquiring execution rights.

  FIG. 4C shows a state of execution in the third embodiment when a real-time task wake-up request is generated in a preemption prohibited section with non-real-time tasks having the same processing contents. Means for prohibiting preemption of the real-time task is provided at a portion where the processing of the preemption prohibition interval is reduced in the preemption prohibition interval. Specifically, this is handled by setting a preemption prohibition flag.

  During the processing of the preemption prohibition section, the step of setting the preemption prohibition flag for prohibiting the preemption of the real-time task is executed subsequent to step 302 of the second embodiment, for example, as shown in FIG.

  That is, as the processing of the preemption prohibition section, if the execution task is determined as a non-real-time task in step 301 and the state of the resource protected in the preemption prohibition section is stored in step 302, whether or not the processing of the preemption prohibition section has decreased (Step 401), the process ends when it is determined that the remaining processing of the preemption prohibition section is not small, and when it is determined that the remaining is small, a preemption prohibition flag for prohibiting the preemption of the real-time task is set (step 402).

  After this preemption prohibition flag is set, even if a real-time task wake-up request is generated, the preemption of the real-time task is made to wait until the processing of the preemption prohibition section is completed. That is, in step 304, it is determined whether or not the non-real-time task is executing the preemption prohibition section. If it is determined that the preemption prohibition section is determined, it is determined whether or not the preemption prohibition flag is set (step 403). If it is determined that is set, the processing of the non-real time task is executed as it is (step 404), and the process is terminated.

  If there are only a few preemption prohibition intervals, it may take more time to restore the resource state in the second embodiment, or the waiting time may not affect the processing of the real-time task. In this case, if the non-real-time task is executed until the end of the preemption prohibition section, it is not necessary to redo the processing of the entire preemption prohibition section, and the performance of the entire system can be improved.

  As described above, if a real-time task wake-up request occurs while a non-real-time task is being executed in a pre-emption prohibited section and the remaining processing of the pre-emption prohibited section is low, pre-emption is disabled and the non-real-time task By executing it to the end, the performance of the entire system can be improved.

In the first embodiment, since the resource state saving process is not executed, the flowchart in which step 302 is deleted in FIG. 5 is executed as the preemption prohibition section process. In the flowchart of FIG. The above step 403 and step 404 are executed in between.
[Embodiment 4]
A fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 6A shows a process executed by a task in a preemption prohibition section, and FIG. 6B shows a process procedure when a real-time task wakeup request interrupt occurs during execution of a non-real-time task.

  As shown in FIG. 6A, as the processing of the preemption prohibition section, at the entrance of the preemption prohibition section, it is determined whether the execution task is a real-time task or a non-real-time task (step 501). When the first resource is allocated (step 502) and the execution task is determined to be a non-real-time task, the second resource is allocated (step 503).

  As shown in FIG. 6B, when a wake-up request interrupt for a real-time task occurs during execution of a non-real-time task, the real-time task wake-up request interrupt is processed (step 504), and the real-time task preempts execution ( Step 505). During execution of the real-time task, execution of the preempted non-real-time task is interrupted.

  When the execution of the real-time task is completed, the non-real-time task re-acquires the execution right (step 506), and the process is resumed from the preempted location using the allocated second resource (step 507).

In this way, real-time tasks can preempt execution of non-real-time tasks at any time, and by allocating resources to be protected in the pre-emption prohibited section and allocating them separately for real-time tasks and non-real-time tasks, Even if the real-time task preempts execution while the real-time task is executing the preemption prohibition interval, resource contention can be avoided and the operations of the real-time task and the non-real-time task can be guaranteed.
[Embodiment 5]
A fifth embodiment of the present invention will be described with reference to FIG.

FIG. 7A shows a run queue process for managing executable tasks, and FIG. 7B shows a process procedure when a real-time task wakeup request interrupt occurs during the second run queue process.
As shown in FIG. 7A, in the run queue process, it is determined whether the task is a real-time task or a non-real-time task (step 601). If the task is determined to be a real-time task, the first run queue is used (step 602). If the task is determined to be a non-real-time task, the second run queue is used (step 603).

  As shown in FIG. 7B, when a wake-up request interrupt for a real-time task occurs during the second run queue process, this real-time task wake-up request interrupt is processed (step 604), and the real-time task preempts execution ( Step 605). While the real-time task is being executed, the execution of the second run queue is interrupted. When the execution of the real-time task is completed, the second run queue process is resumed from the preempted location (step 606).

  In this way, by dividing the run queue into a real-time task and a non-real-time task, it is possible to avoid a problem in the system even if the real-time task preempts execution while the non-real-time task is executing the second run queue. it can.

  The real-time control method according to the present invention can preempt execution of a non-real-time task in any case of a real-time task, and includes a mixture of non-real-time processing that performs control of home appliances that require real-time processing and user interface processing. It is useful as a system for network home appliances.

It is a flowchart explaining the real-time control system in Embodiment 1 of this invention. It is a figure for demonstrating the effect of the real-time control system. It is a flowchart explaining the real-time control system in Embodiment 2 of this invention. It is a figure for demonstrating Embodiment 3 of this invention. It is a flowchart explaining the real-time control system in Embodiment 3 of this invention. It is a flowchart explaining the real-time control system in Embodiment 4 of this invention. It is a flowchart explaining the real-time control system in Embodiment 5 of this invention.

Claims (5)

In a real-time control method in a system where real-time tasks that require real-time processing and non-real-time tasks that do not require real-time processing coexist,
Processing a real-time task wake-up request interrupt while executing a non-real-time task;
Determining whether a non-real-time task being executed is executing a preemption prohibited section; and
When determining that the preemption prohibition section is being executed, a step of setting a flag for recording that the preemption is prohibited by the real-time task in the preemption prohibition section;
A real-time task that preempts execution;
When the real-time task ends, the preempted non-real-time task reacquires execution rights;
Determining whether the flag is set;
Resuming that the flag is set, resuming processing of the non-real-time task from the beginning of the preemption prohibition section;
And a step of resuming processing of the non-real time task from a preempted location when it is determined that the flag is not set. In a real-time control method in a system where real-time tasks that require real-time processing and non-real-time tasks that do not require real-time processing coexist,
As preemption prohibition section processing,
Determining whether the execution task is a real-time task or a non-real-time task;
When the execution task is determined to be a non-real-time task, it includes a step of saving the resource state protected in the preemption prohibition section process,
Processing a real-time task wake-up request interrupt while executing a non-real-time task;
Determining whether a non-real-time task being executed is executing a preemption prohibited section; and
When it is determined that the preemption prohibition section is being executed, a flag for recording that the preemption is performed by the real-time task in the preemption prohibition section is set, and the saved resource state is restored.
A real-time task that preempts execution;
When the real-time task ends, the preempted non-real-time task reacquires execution rights;
Determining whether the flag is set;
Resuming that the flag is set, resuming processing of the non-real-time task from the beginning of the preemption prohibition section;
And a step of resuming processing of the non-real time task from a preempted location when it is determined that the flag is not set. As processing of preemption prohibition section,
Determining whether the execution task is a real-time task or a non-real-time task;
When the execution task is determined to be a non-real-time task, a step of determining whether or not the processing of the preemption prohibition section has decreased,
3. The real-time control system according to claim 1, further comprising a step of prohibiting pre-emption of a real-time task when it is determined that the remaining processing of the pre-emption prohibition section has been reduced. In a real-time control method in a system where real-time tasks that require real-time processing and non-real-time tasks that do not require real-time processing coexist,
As preemption prohibition section processing,
Determining whether the execution task is a real-time task or a non-real-time task;
Allocating a first resource if the execution task is determined to be a real-time task;
Allocating a second resource when the execution task is determined to be a non-real-time task,
Processing a real-time task wake-up request interrupt while executing a non-real-time task;
A real-time task that preempts execution;
When the real-time task ends, the preempted non-real-time task re-acquires execution rights;
Resuming execution from the location where the non-real-time task is preempted using the allocated second resource. In a real-time control method in a system where real-time tasks that require real-time processing and non-real-time tasks that do not require real-time processing coexist,
Determining whether a task is a real-time task or a non-real-time task in the run queue process for managing executable tasks;
Determining that the task is a real-time task, using the first run queue;
Determining that the task is a non-real time task, using a second run queue;
Processing a real-time task wake-up request interrupt while using the second run queue;
A real-time task that preempts execution;
And a step of resuming the preempted process when the real-time task is completed.

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