JPH11120071A - Common memory access system for processes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the system which allows processes to access a common memory at the same time without waiting for other processes to end when control is performed by using the common memory that processes can access in common. SOLUTION: This system performs one piece of control by a plurality of control processes 11 to 1n and is equipped with the common memory 3 that the control processes 11 to 1n can access in common and also equipped with a common control table 4 that the control processes 11 to 1n use in common in the common memory 3. In this case, the system is provided with a common control table access process 2 which accepts access indications from the control processes 11 to 1n and accesses the common control table 4, thereby allowing the control processes 11 to 1n to access the common control table 4 through the common control table access process 2 without waiting for other processes to end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access control method for a shared memory, and more particularly, to a method for providing a shared memory that can be accessed by a plurality of processes in common and enabling a plurality of processes to access the shared memory at the same time.

[0002]

2. Description of the Related Art In a system in which one process is controlled by a plurality of processes, each process has a shared memory that can be accessed in common, and a common control table in which each process performs common control is provided in each shared memory. When a process accesses the common control table, it is necessary to perform exclusive control such as by locking the common control table before accessing the common control table so that a plurality of processes do not access at the same time. . For this reason, it is necessary to lock the table every time each process accesses the common control table, and a plurality of processes cannot access the common control table at the same time, which causes a processing delay.

As a conventional shared memory access method,
Japanese Patent Laid-Open Publication No. Hei 5-289894 discloses a method for avoiding data conflict between tasks sharing a memory in order to enable use of a subroutine that is not reentrantly programmed between tasks sharing a memory area. In a shared memory environment in which multiple tasks that share a single memory device or a single virtual memory space execute, a program area shared by all tasks, a data area shared by all tasks, and a plurality of task groups When a subroutine is called with a program area shared by tasks belonging to each group and a unique data area allocated to each task, and a subroutine address table for each task or each task group To the address of the subroutine Thus, a method is disclosed in which a subroutine of a program area shared by each group is called, and a unique data area of each task is accessed in a subroutine of a program area of a program shared by each group. .

[0004]

However, the above conventional method has the following problems.

That is, when a plurality of tasks simultaneously access a data area shared by all tasks or a data area shared by a task group, when a certain task accesses a data area shared by
Other tasks are unable to access the shared data area and need to suspend processing.

The reason is that if a task accesses the same location in the shared data area while another task is accessing the shared data area, an illegal access may occur due to contention in access processing. It is because it becomes.

Accordingly, the present invention has been made in view of the above problems, and has as its object to control a plurality of processes by using a shared memory which can be commonly accessed by the plurality of processes. An object of the present invention is to provide an access method that enables access to a shared memory without waiting for processing of another process even when accessing the shared memory at the same time.

[0008]

In order to achieve the above object, according to the present invention, an access method for a shared memory of a plurality of processes is a shared memory including a common control table commonly used by a plurality of processes executed on a computer. In a memory access control method, a common control table access control means for receiving access instructions from the plurality of processes and accessing the common control table according to the access instructions is provided, and each of the processes accesses the common control table. In this case, an access instruction is issued to the common control table access control unit without directly accessing the common control table, and the common control table is accessed via the common control table access unit. And

According to the method of accessing a shared memory of a plurality of processes according to the present invention, one control is performed by a plurality of control processes, and the plurality of control processes include a shared memory that can be commonly accessed. In a system including a common control table commonly used by the control process, a system having a common control table access process for receiving an access instruction from the control process and accessing the common control table, wherein a plurality of the control processes, When the common control table is accessed, the common control table can be accessed via the common control table access process without waiting for the processing of another control process.

[0010]

Embodiments of the present invention will be described below. An access method of a shared memory of a plurality of processes according to the present invention, in a preferred embodiment thereof,
The control process (11 to 1n in FIG. 1) accesses the common control table (4 in FIG. 1) in the shared memory (3 in FIG. 1) without directly accessing the common control table.
An access instruction is notified to a common control table access process (2 in FIG. 1) for accessing the common control table.

A common control table access process that has received an access instruction from the control process (2 in FIG. 1).
Accesses the common control table (4 in FIG. 1) in the shared memory according to the contents of the access instruction.

In the embodiment of the present invention, when a plurality of control processes try to access the common control table at the same time, an access instruction is sent to the common control table access process without directly accessing the common control table. Notice. The common control table access process that has received an access instruction from a plurality of control processes accesses the common control table in the order in which the access instructions have been received. For this reason, the control process can access the common control table without waiting for the processing of another control process, thereby improving the overall processing throughput.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention;

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. Referring to FIG. 1, in one embodiment of the present invention, a plurality of control processes 11 to 1n for performing one control are performed.
And a shared memory 3 that can be commonly accessed by the control processes 11 to 1n, and a common control table 4 provided in the shared memory 3 and commonly used by the control processes 11 to 1n.
And a common control table access process 2 that receives an access instruction from each of the control processes 11 to 1n and accesses the common control table 4.

FIG. 2 is a flowchart showing a processing flow of an embodiment of the present invention. The operation of one embodiment of the present invention will be described below with reference to FIGS.

In the control process 1n, the shared memory 3
When an event for accessing the common control table 4 occurs in step (step 21), an access instruction is notified to the common control table access process 2 irrespective of the processing of other control processes (step 22).

The common control table access process 2 comprises:
When an access instruction is received from the control process 1n, the access instruction is received, and it is determined whether or not there is a process that has not yet accessed the common control table 4 (step 23). If there is, the process waits for completion of the process that has not yet accessed the common control table 4 (step 24).

In step 23, if there is no process that has not yet accessed the common control table 4, the common control table 4 is accessed according to the access instruction received from the control process 1n (step 25).

Regardless of the result of the determination in step 23, the control process 1n continues the processing after notifying the access instruction.

FIG. 3 is a diagram for explaining an embodiment in which the present invention is applied to a character search system for a file. As a control process, a plurality of character strings for searching a specific character string in a file are searched. Is provided with a character string counter for storing a search result as a common control table of a shared memory.

More specifically, referring to FIG. 3, a plurality of character string search processes 11 to 1n for searching a file for a specific character string, and a plurality of character string search processes 11 to 11n.
1n, a character string counter 4 'for storing search results from the character string search processes 11 to 1n in the shared memory 3, and access from the character string search processes 11 to 1n. A common control table access process 2 for receiving an instruction and updating a character string counter 4 'in the shared memory 3.

A plurality of character string search processes 11 to 1n
Searches for a character string from a file independently, and when a character string to be searched is found (step 21 in FIG. 2), notifies an access instruction to the common control table access process 2 (step 22 in FIG. 2). ). Upon receiving the access instruction, the common control table access process 2 determines whether or not there is a process that has received the access instruction and has not yet updated the character string counter 4 '(step 23 in FIG. 2). If there is a process that has not yet updated the character string counter 4 ', the process waits for completion of a process that has not yet updated the character string counter 4' (step 2 in FIG. 2).
4).

In step 23 of FIG. 2, if there is no process that has not yet updated the character string counter 4 ', the character string counter 4' is updated according to the access instruction received from the character string search processes 11 to 1n. (Step 25 in FIG. 2). Then, irrespective of the determination result in step 23, the character string search processes 11 to 1n continue the search processing of the character string from the file after notifying the access instruction.

[0024]

As described above, according to the present invention,
When multiple control processes access the common control table in the shared memory at the same time, each control process issues an access instruction to the common control table access process regardless of whether another control process is accessing the common control process. , The access to the common control table is enabled, and by continuing the processing after the access to the common control table, there is an effect that the overall throughput is improved.

The reason is as follows. That is,
When multiple control processes directly access the common control table in the shared memory at the same time, it is necessary to exclusively access the common control table. Although it is necessary to access the control table, in the present invention, when the control process accesses the common control table, it issues an access instruction to the common control table access process, and This is because the method of accessing the common control table becomes a single process to access the common control table, and it is not necessary for the control process to perform control to exclusively access the common control table.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an embodiment and an example of the present invention.

FIG. 2 is a flowchart for explaining the operation of one embodiment of the present invention.

FIG. 3 is a diagram showing an embodiment in which the present invention is applied to a character string search of a file.

[Explanation of symbols]

 11-1n control process (character string search process) 2 common control table access process 3 shared memory 4 common control table 4 'character string counter

Claims (3)

[Claims] 1. One control is performed by a plurality of control processes.
In a system including a shared memory commonly accessible by the plurality of control processes, and a common control table used by the control processes in the shared memory, an access instruction from the control process is received; A common control table access process for accessing a control table, wherein the plurality of control processes, when accessing the common control table, do not wait for the processing of another control process, and via the common control table access process. A shared memory access method for a plurality of processes, wherein the shared control table is made accessible. 2. An access control method for a shared memory including a common control table commonly used by a plurality of processes executed on a computer, wherein an access instruction from the plurality of processes is received, and the common control is performed according to the access instruction. A common control table access control means for accessing a table, wherein each of the processes, when accessing the common control table, does not directly access the common control table, but issues an access instruction to the common control table access control means. And accessing the common control table via the common control table access means. 3. The shared memory access method for a plurality of processes according to claim 2, wherein said common control table access control means accesses said common control table in accordance with an access instruction from said process.