JP2607595B2 - Queuing table search method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a table which retrieves a target table from a group of tables queued under the management of a nucleus which is a core of an OS (Operating System), or a table retrieved. Related to a queuing table search method for referring to, for example, an event-driven real-time
The present invention relates to a technique which is effective when applied to improvement of real-time property (immediate responsiveness) to an external interrupt generated asynchronously at the time of a queuing table search in an OS.

(Prior art)

With the role and importance of OSs increasing with the expansion of application fields of microcomputer systems, real-time OSs applied to industrial applications such as measurement control systems usually support multitasking for the purpose of real-time control. Therefore, a real-time processing speed that can immediately execute an external device or an internal processing request is required. In particular, when real-time performance is emphasized, immediate responsiveness to an asynchronous external interrupt is required.

By the way, the nucleus, which is the core of the real-time multi-task processing of the OS, recognizes an asynchronous event that occurs from an external device or from inside, and executes a task corresponding to the processing result of the event. Is scheduled according to the priority, and a system call (processing request) from a task is received to perform the processing. For example, the nucleus is an MPU
A scheduler that schedules the order of assigning (micro-processing units) to tasks according to task priorities; task management to manage task states such as task creation, activation, termination, and deletion; and time monitoring for task execution control Function modules such as timer management, which performs task allocation, memory management, which secures the allocation of memory areas required for tasks, and synchronization / communication management, which performs synchronization / communication processing between tasks, as well as interrupt processing due to external interrupts and interruption to tasks It is composed of non-tasks such as an interrupt handler that reports occurrence and an exception handler that performs processing for exception interrupts and system call error processing.

These function modules accept system calls and perform predetermined processing. For example, when a task is generated by a task management system call, a task-specific ID (identification), priority, and the like of the task are added. A start address and the like are assigned to a working area of the OS. Such allocation to the working area is also performed on the event flags, mailboxes and semaphores generated by the synchronization / communication management, and also on the IDs and sizes of the memory pools generated by the memory management. In this manner, various information allocated to the working area of the OS is queued in a management block corresponding to the content to form a table group.

Under the management of the nucleus, the various queuing tables configured as described above are appropriately assigned based on system calls issued from tasks and system calls issued from non-tasks such as interrupt handlers and exception handlers. Additions and deletions are made.

By the way, when various external interrupts are input during nucleus processing, this processing is interrupted each time, and when the cause of the interruption is released, the processing returns to the original state. When a system call that starts a new task from a task is issued,
A system call instructing addition or deletion of a queuing table to the working area of the OS may be made from a task started by the system call. Furthermore, there is a case where a non-task such as an interrupt handler issues a system call for directly adding or deleting a queuing table. In such a case,
When the cause of the interruption caused by the interrupt is released and the state returns to the original state, the contents of the working area of the OS have already been changed.

Conventionally, when a change in the contents of the working area of the OS due to an interrupt may undesirably affect the nucleus processing after the cancellation of the interruption factor, a method of masking an external interrupt during the processing has been adopted.

An example of a document describing a real-time OS is "Microcomputer Handbook" P546 to P556 issued by Ohmsha on December 25, 1985.

[Problems to be solved by the invention]

However, for external devices and internal processing requests,
In a real-time OS that requires real-time processing speed that can perform immediate processing, if the period for masking external interrupts during nucleus processing becomes longer, the requirement for immediate response to asynchronous external interrupts may be satisfied. Can not be done and the performance degradation cannot be avoided. According to the study of the present inventors, a particular problem is a case where a queuing table formed in the working area of the OS is searched. In other words, the number of a series of queuing tables corresponds to the maximum number of tasks that can be registered in the OS, and the processing time for selecting such tables one by one and examining their contents is extremely long depending on the position of the target table. In the meantime, if all the high-priority processes are put in the waiting state, the performance of an OS that advocates real-time performance is reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a queuing table search method in which the immediate response to an interrupt generated asynchronously is improved.

The above and other objects and novel features of the present invention are as follows.
It will be apparent from the description of this specification and the accompanying drawings.

[Means for solving the problem]

The outline of a representative invention among the inventions disclosed in the present application will be briefly described as follows.

In other words, in a queuing table search method in which the contents are checked while sequentially pointing to a plurality of queued tables that are allowed to be added and deleted under the control of the nucleus, and a search process is performed to reach a target table. A first process for resetting the table change flag in a state where interrupt acceptance is prohibited before performing a search process on the queued top table, and an interrupt for enabling interrupt acceptance after the first process A second process for forming an open period, and changing the table change flag to a set state when an interrupt is received during the interrupt open period and the interrupt involves deletion or addition of the queued table. Third processing, after the end of the interrupt release period or the interrupt release period After the accepted interrupt processing is completed, the state of the table change flag is determined, and if the determination result is the set state, the first processing is performed again to search the queued top table. And a fourth process for restarting the process.

(Operation)

According to the above-described means, when an interrupt is generated during the interrupt release period included in a series of steps for sequentially selecting a plurality of tables queued in the working area of the OS and searching for the target table, An interrupt handler corresponding to the type of interrupt, for example, an interrupt vector number, is activated. When a table is added to or deleted from a group of tables to be searched based directly or indirectly on a system call issued during the processing of this interrupt handler operating in the supervisor mode, a flag corresponding to this is added. Is set. If an interrupt is generated during the interrupt release period, but no table is added or deleted from the search target table group due to this, and if no interrupt is generated during the interrupt release period, the above flag is reset. Keep. The state of this flag is checked after the end of the interrupt release period, or at a step after the interrupt handler returns to the original control state after an interrupt occurs during the interrupt release period. As a result of this inspection, if the flag is kept in the reset state, since addition or deletion of tables from the table group to be searched has not been performed from the start of the search to the present, the next table search loop Moved to execution. on the other hand,
As a result of the inspection, if the flag is inverted to the set state, it means that addition or deletion has been performed on any of the tables to be searched, and such a change in the table is searched. In order to cope with the possibility of affecting the completed table, the search processing of the queuing table is restarted from the top table, ignoring past search results that may be stochastically invalid.

In this way, it is possible to cope with a change in the search target table due to notification of an event from an external interrupt and to enable an interrupt during the search of the queuing table, thereby improving the immediate response of the OS to an asynchronous interrupt. is there.

〔Example〕

The queuing table search method according to the present embodiment is applied to a microcomputer system having an event-driven real-time OS. Although not shown, the microcomputer system includes a main unit such as a micro processing unit, a random access memory (RAM), and a ROM.
(A read-only memory), an auxiliary storage device, and an input / output controller are interfaced so that information can be exchanged with each other, and the input / output controller, the main storage device, and the auxiliary storage device hold the information. A predetermined task is processed using various data and programs. Real-time OS
Are stored in a ROMized auxiliary storage device, although not particularly limited.

The nucleus that forms the core of the real-time OS is not particularly limited, but a scheduler that schedules the order in which microprocessing units (not shown) are assigned to the tasks in accordance with task priorities, and task states such as task creation, activation, termination, and deletion. Functions such as task management for managing tasks, timer management for monitoring time for task execution control, memory management for allocating memory areas required for tasks, and synchronization and communication management for synchronization and communication processing between tasks It is composed of modules and non-tasks such as an interrupt handler for notifying an interrupt process due to the occurrence of an external interrupt and the occurrence of an interrupt to a task, and an exception handler for performing a process for an exception interrupt and a system call error process.

Various working areas of the real-time OS and user memory areas required for tasks are formed in the main storage device (not shown).

The working area of the real-time OS includes various management blocks such as a task management block and a memory management block set corresponding to the function module of the OS, and each management block is queued under the control of the real-time OS. This constitutes a group of tables. Note that the queued table group or a table included in the table group is also referred to as a queuing table hereinafter.For example, each of the tables constituting the task management block includes an ID and a priority unique to the generated task, and furthermore, Queued including the start address of Further, each table constituting the memory management block is queued including information such as the ID of the allocated memory pool and its size. Further, queues for task activation requests and memory pool generation requests are also formed in the working area as queuing tables.

Under the management of the nucleus, the various queuing tables configured as described above are appropriately assigned based on system calls issued from tasks and system calls issued from non-tasks such as interrupt handlers and exception handlers. Additions and deletions are made.

FIG. 1 is a flowchart showing one embodiment of a queuing table search method according to the present invention, and FIG. 2 is a flowchart of a table change module for adding or deleting a queuing table.

First, the table change module shown in FIG. 2 adds and deletes a queuing table, that is, generates and deletes a task, generates and deletes a memory pool, and generates and deletes an event flag, a mailbox, and a semaphore. Module that processes system calls for Although this module is shown as one module, it is actually included in each function module such as task management and memory management that constitute the real-time OS. The table change module sets a table change flag to “1” when processing a system call involving addition or deletion of a queuing table.

In the queuing table search process, first, the external interrupt is prohibited (step S1), the table change flag is reset to "0" (step S2), and the first table address to be searched is pointed (step S2).
S3).

Before checking the pointed table, release the external interrupt once (step S4), disable the external interrupt again (step S5), and then check the table change flag (step S6). If the result is reset, The contents of the previously pointed table are checked by collation with the designated information for search (step S7). When it is determined that the table does not match the target table (step S8), it is determined whether the search has been performed to the end of the queued table (step S8).
S9) If it is in the middle, point to the address of the table arranged next (step S10), and return to step S4. Thus, a search loop is formed while the address points of the table are sequentially updated.

In the search processing of the queuing table of the present embodiment, an external interrupt release period (step S4 to step S5) is formed for each search loop, during which the external interrupt IRQ is set.
Is generated, the search process is interrupted, and the process returns to the original process after the cause of the interrupt is removed.

At this time, if the interrupt IRQ issues a system call that starts a new task from a non-task such as an interrupt handler, the task started by the system call adds or deletes the queuing table to the working area of the OS. An instructing system call may be made. Furthermore, there is a case where a non-task such as an interrupt handler issues a system call for directly adding or deleting a queuing table. At this time, the table change flag is set to "1" by the table change module shown in FIG.

When the queuing table is added or deleted due to the external interrupt IRQ generated during the interrupt release period,
Step S6 of the search loop corresponding to the interrupt release period
Detects the set state of the table change flag. In this case, addition or deletion is performed on any of a series of queuing tables to be searched, and such a change in the table affects the searched table. In order to deal with the possibility, the search processing is returned to step S2 in order to restart the search processing of the queuing table from the head table while ignoring the past search results that may be stochastically invalid.

In this way, if there is a target table while the queuing tables are sequentially selected and their contents are checked, the process branches off from the search loop in step S8 and the queuing table search processing is normal. Then, the external interrupt is released (step S12), and the series of search processing ends.
If there is no table that matches the target table in the final table, the process branches from the search loop in step S9, and processing is performed to the effect that the queuing table search process is abnormal (step S13). The external interrupt is released (step S12), and the series of search processing ends.

According to the above embodiment, the following effects can be obtained.

(1) In the case where a queuing table formed in the working area of the OS is searched, the number of a series of queuing tables corresponds to the maximum number of tasks that can be registered in the OS. The processing time for selecting and examining the contents can be extremely long depending on the position of the target table. However, in the search processing of the queuing table of the present embodiment, the external interrupt release period (steps S4 to S4) is performed in one search loop. Since step S5) is formed, all the high-priority processes are not put into a wait state until a series of search processes are completed, and queuing is performed by improving the immediate response to an external interrupt generated asynchronously. You can search the table.

For example, if 100 tables are queued and the target table is the last table, and the conventional search logic requires 20 μsec for one search loop, the target table is searched. An external interrupt is put into a wait state while 2000 μsec corresponding to 100 search loops elapses. On the other hand, in the method of the present embodiment, the processing of steps S4, S5, and S6 is added to one search loop, and the time required for one search loop slightly increases. Since the open period is provided, the immediate response to the external interrupt at the time of searching the queuing table is remarkably improved.

(2) When an external interrupt is generated during the external interrupt release period (step S4 to step S5) formed for each search loop, if the queuing table is added or deleted by the interrupt, the table is changed. The table change flag of the module is set to "1", the state of the table change flag is checked for each search loop in step S6, and when the set state is detected, such a change in the table is set in the searched table. In order to cope with the possibility of influence, ignore past search results that may be stochastically invalid and restart the queuing table search process from the top table, so that external interrupts are performed for each search loop Opening an external interrupt for each search loop, responding appropriately to changes in the search target table that may occur by opening It can be.

(3) From the above-mentioned respective effects, the immediate response of the real-time OS to an interrupt generated asynchronously can be improved.

The invention made by the present inventor has been specifically described based on the embodiments, but the present invention is not limited thereto, and can be variously modified without departing from the gist thereof.

For example, the queuing table search method of the present invention is not limited to application to a real-time OS,
The present invention can be applied to an OS for program development as well as an OS for program development that enables real-time processing.

In the above description, the case where the invention made by the present inventor is mainly applied to the search processing of the objective table which is the field of use as the background has been described. However, the present invention is not limited to this. The present invention can also be applied to a case where the contents are referred to while sequentially searching. INDUSTRIAL APPLICABILITY The present invention can be applied to a condition in which a predetermined process is performed while cyclically selecting at least a queued table.

〔The invention's effect〕

The effects obtained by the representative inventions among the inventions disclosed in the present application will be briefly described as follows.

That is, a series of steps for searching for a target table from the queuing table includes forming an interrupt release period that allows external interrupts to be accepted, and thereafter detecting a flag indicating a change in the queuing table, If there is a change in the queuing table due to an interrupt that occurred during the interrupt release period, it is probabilistically invalid to address the possibility that such a change in the table may have affected the searched table. By restarting the queuing table search process from the top table etc. ignoring the past search results that may possibly occur, the queuing table Enables interrupts in the middle of a search, thereby providing an immediate response to interrupts that occur asynchronously. Sex can be obtained queuing table search method with improved, with it, there is an effect that it is possible to improve the immediate response of the OS to interrupts generated asynchronously.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a queuing table search method according to the present invention, and FIG. 2 is a flowchart of a table change module for adding or deleting a queuing table. S4 to S5: Interrupt release period, S6: Table change flag detection step, IRQ: External interrupt.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Tsuyoshi Shimizu 1450 Kamisumihoncho, Kodaira-shi, Tokyo Inside Musashi Plant of Hitachi, Ltd. (56) References JP-A-59-189452 (JP, A) Akira Tokubo 58-28611 (JP, B2)

Claims (1)

(57) [Claims] 1. A queuing table for searching for contents while sequentially pointing to a plurality of queued tables permitted to be added and deleted under the control of a nucleus and performing a search process for reaching a target table. In the search method, a first process in which the table change flag is reset in a state where interrupt acceptance is disabled before performing a search process on the queued top table, and an interrupt can be accepted after the first process A second process for forming an interrupt release period, and setting the table change flag when an interrupt is received during the interrupt release period and the interrupt involves deletion or addition of the queued table. And a third process for changing the interrupt release period after the end of the interrupt release period or the interrupt release period The state of the table change flag is determined after the interrupt processing accepted in the middle is completed, and if the determination result is the set state, the first table is queued by performing the first processing again. A queuing table search method, comprising the steps of: starting a search process again;