JPH10247161A - Memory management system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accept the synchronous processing such as an interrupt, etc., and to always perform the acquisition/release processing even in a synchronous processing mode by preserving the processing situation right before the acquisition/release processing, restoring the preserved processing situation against the report of an exception, and then executing again the acquisition/ release processing. SOLUTION: The processing situation obtained before the acquisition/release processing is preserved when the acquisition/release processing of a memory is started in a process A (101). When the asynchronous processing like an interrupt, etc., occurs during the memory acquisition/release processing of the process A and then this acquisition/release processing is executed (103), the process A discriminates whether the memory acquisition/release processing is presently executed or not (104). If this processing is executed, the occurrence of the exception processing is notified to the said processing (105). In an exception processing mode, the preserved situation is restored (107) and the memory acquisition/ release processing is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory management system for dynamically acquiring / releasing a memory of a system by a plurality of interrupt processes, and more particularly to a memory management system in a system in which responsiveness to an external event such as an interrupt is important. .

[0002]

2. Description of the Related Art Conventionally, in this type of memory management, execution of asynchronous processing such as interrupts is prohibited during memory acquisition / release processing by a certain processing, or memory acquisition / release processing is performed. In general, there is a restriction that it must not be performed in asynchronous processing.

[0003] Due to such a limitation, during the memory acquisition / release processing in a certain processing, the memory acquisition / release processing cannot be performed by asynchronous processing such as interrupt processing. Further, in order to enable the memory acquisition / release processing to be always performed in the asynchronous processing, an interrupt cannot be executed during the memory acquisition / release.

That is, execution of asynchronous processing such as interruption during memory acquisition / release processing is prohibited. For example, while a certain application is acquiring memory, it is not possible to switch to another task by interruption.

As a system for dynamically managing this kind of memory, for example, there is a memory control system disclosed in Japanese Patent Application Laid-Open No. 3-68044. Appropriate permission / prohibition of securing a system shared memory for each user task. Has been proposed so that other user tasks are not inconvenienced due to runaway of a specific user task or the like by controlling the user task.

[0006]

As described above, in the conventional memory management method, during the memory acquisition / release processing,
In order to prohibit asynchronous processing such as interrupt processing from performing memory acquisition / release processing, or to enable memory acquisition / release processing to be performed constantly in asynchronous processing, interrupts must be issued during memory acquisition / release. Had been banned.

However, since the time required for the memory acquisition / release processing changes according to the memory utilization status,
The conventional memory management method has a problem that it is difficult to predict the worst case interrupt prohibition time, and it is difficult to guarantee the real-time responsiveness of the system.

Although various techniques for sharing a memory with a plurality of tasks have been proposed as in the above-mentioned Japanese Patent Application Laid-Open No. 3-68044, memory acquisition / processing in a certain process has been proposed.
No technique has been proposed for accepting an interrupt during the release processing and enabling memory acquisition / release processing by the interrupt processing.

An object of the present invention is to make it possible to accept an asynchronous process such as an interrupt even during a memory acquisition / release process, and to perform a memory acquisition / release process at all times even in the asynchronous process. It is an object of the present invention to provide a memory management method that can always accept asynchronous processing requiring real-time responsiveness.

[0010]

According to the memory management method of the present invention which achieves the above object, when a memory acquisition / release processing is performed in the first processing, a processing status immediately before the acquisition / release processing is stored. A step of notifying an occurrence of an exception to the first processing when the second processing by interruption performs a memory acquisition / release processing during the memory acquisition / release processing; Recovering the processing status saved in the first processing and executing the memory acquisition / release processing again when the notification of the exception is received during the memory acquisition / release processing by the processing. Features.

According to a second aspect of the present invention, when the second process by the interruption is the acquisition / release of the memory, it is determined whether the acquisition / release of the memory is being performed in the first process. If the memory is being acquired / released, the occurrence of the exception is notified to the first process, and if the memory is not being acquired / released, the process returns from the interrupt.

According to a third aspect of the present invention, in the memory management method, the process of restoring the saved processing status is defined as an exception process, and the exception process is called upon notification of the exception. . In addition, the first processing is performed when the memory is not acquired / acquired unless the exception is notified.
The release processing is continued as it is.

[0013]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart for explaining the processing content of a memory management method that guarantees real-time responsiveness according to an embodiment of the present invention.

When a certain process A starts a memory acquisition / release process, the status of the process before acquisition / release is stored (step 101). That is, the contents of various registers and the program count (processing status; context) immediately before the memory acquisition / release processing are stored. As a result, by restoring the saved processing status, the memory acquisition /
It is possible to return to the state before the release processing. After the status has been saved, a memory acquisition / release process is performed (step 102).

During the memory acquisition / release processing of the processing A, a processing B, which is an asynchronous processing such as an interrupt, occurs.
When the memory acquisition / release processing is performed in (step 10
3) The process B determines whether the memory acquisition / release process is being performed by another process (process A) (step 104).
If the memory acquisition / release processing is being performed in another processing, the occurrence of exception processing is notified to the processing (step 10).
5). If memory acquisition / release processing is not being performed in other processing,
Alternatively, the process returns from the interrupt after the end of the notification of the occurrence of the exception process.

When the process returns from the asynchronous process and returns to the interrupted process A, it is determined whether or not the exception process has been notified (step 106). If the exception process has been notified, the exception process is started.

In the exception processing, the situation saved in step 101 is restored (step 107).

Then, as a result of the restoration of the situation, the memory acquisition / release processing of step 102 is started again.

If no exception occurs during the memory acquisition / release processing, the memory acquisition / release processing in step 102 succeeds, and the memory acquisition / release processing ends.

With the above processing, it is possible to accept an asynchronous process such as an interrupt even during the memory acquisition / release processing, and the memory acquisition / release processing can always be performed in the asynchronous processing.

[0021]

Next, an embodiment of the present invention will be described in detail with reference to FIG. The embodiment shown in FIG. 2 shows an example of a program in C language for realizing the memory management method of the present invention. In this embodiment, only the process of acquiring the memory is described, but the process of releasing the memory can be similarly performed. In this embodiment, an external interrupt is assumed as an example of the asynchronous processing.

Here, "ID" is a type of an identifier of a processing flow, and "struct context" is a structure name of a data area for storing a processing state.

In FIG. 2, the procedure "mem_new"
Is a process for acquiring a memory. This memory acquisition routine lists the “ID” of the process during the memory acquisition process in the list “li”.
st ". The structure of this list is "idli
st ”structure. The “idlist” structure includes a field “ID” for storing the processing “ID”, a field “cx” for storing the status, and a list link field.

The procedure "mem_exception" is an exception process. This processing is performed by the procedure “raise_ex
It is assumed that it is set to be called when an exception is notified by “ception”.

Next, the contents of the embodiment shown in FIG. 2 will be described.

(1) When the procedure "mem_new" starts processing, the procedure "save_context" saves the current processing status (contents of various registers and program counts).

(2) Obtain the ID of the current process and register it in the list "list".

(3) Perform memory acquisition processing. Here, the free list of the memory is searched, a free memory area satisfying the required size is searched, and the process of reducing the size of the acquired memory block is performed.

(4) When the memory acquisition processing is completed, the processing is registered in the list and the current processing is deleted.

(5) If the list is not empty, it means that another process has interrupted the memory acquisition of its own process and performed the memory acquisition process.

(6) In this case, an exception is notified to the processing during acquisition of the memory connected to the list list.

(7) In the process notified of the exception, an exception process “mem_exception” is called. This processing is performed in “raise_exception” in (6).
After returning to the process to which the exception has been notified, the process is called immediately before the interrupted process is continued.

(8) Exception processing “mem_excepti”
on ", the procedure" recover_contex "
By "t", the situation saved in (1) is restored. As a result, the processing is executed again from the memory acquisition / release processing of (2).

Although the present invention has been described with reference to the preferred embodiments and examples, the present invention is not necessarily limited to the above embodiments and examples.

[0035]

As described above, according to the memory management method of the present invention, when the memory acquisition / release processing is performed in the first processing, the processing status immediately before the acquisition / release processing is stored, and By interrupt during acquisition / release processing of
When the process performs memory acquisition / release processing, the occurrence of an exception is notified to the first processing, and when the exception is received during the memory acquisition / release processing by the first processing, the information is saved. By restoring the processing status and executing the memory acquisition / release processing again, asynchronous processing such as an interrupt can be accepted even during the memory acquisition / release processing, and the memory is always acquired during the asynchronous processing. / Release processing can be performed, and memory management that can always accept asynchronous processing that requires real-time responsiveness is realized.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating the contents of a memory management method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a program example as an embodiment for realizing the memory management method of the present invention.

[Explanation of symbols]

 101 Status Save Process 102 Memory Acquisition / Release Process 103 Memory Acquisition / Release Process by Interrupt 105 Exception Occurrence Notification Process 107 Save Status Restore Process

Claims (4)

[Claims] When performing a memory acquisition / release process in a first process, a step of saving a processing status immediately before the acquisition / release process; and a second process performed by an interrupt during the memory acquisition / release process. When the process performs a memory acquisition / release process, the first
Notifying the occurrence of an exception to the processing of step (a), and restoring the processing state saved in the first processing if the notification of the exception is received during the memory acquisition / release processing by the first processing And executing a memory acquisition / release process again. 2. At the end of the memory acquisition / release processing in the second processing due to the interruption, it is determined whether the memory is being acquired / released in the first processing. 2. The memory management method according to claim 1, wherein the occurrence of the exception is notified to the first process, and if the memory is not being acquired / released, the process returns from the interrupt. 3. The memory management method according to claim 1, wherein a process of restoring the saved processing status is defined as an exception process, and the exception process is called upon notification of the exception. 4. The memory management method according to claim 1, wherein in the first processing, if the exception is not notified, the memory acquisition / release processing is continued as it is.