JPS63149741A - Descriptor table control system - Google Patents

Abstract

PURPOSE:To improve the using efficiency of a memory by constituting a local descriptor table (LDT) so as to include increases descriptors and arranging the LDT on a position capable of storing it in the whole memory. CONSTITUTION:The whole memory area 1 is used as a storage area of the LDT, and when an LDT area 50 to be increased can not be increased as it is, a blank memory area 51 capable of storing the area 50 is detected by a table processing means 2, the original LDT is copied in the area 51 and the increased descriptor is written in the area. Since it is unnecessary to prepare an area capable of storing the maximum number of possible descriptors in each LDT, the area using the memory as the LDT can be reduced and the using efficiency of the memory can be improved.

Description

[Detailed description of the invention] 〔overview〕 Code and data for each task (one process).

In a descriptor table management method in which the processor manages the memory address space using a local descriptor table (hereinafter referred to as LDT) consisting of descriptors in units of segments (blocks) such as stacks, the LDT is held for each task. This is the same as before, but when the number of descriptors increases, the LDT configuration is changed to a configuration that includes the increased number of descriptors, and this arrangement is set at a position on the entire matrix that can accommodate the increased number of descriptors. This eliminates the need for each LDT to have an area capable of storing the maximum number of descriptors that may increase, thereby improving memory usage efficiency.

[Industrial application field]

The present invention uses an LDT consisting of descriptors for each segment such as code, data, and stack for each task.
This paper relates to an improvement in a descriptor table management method in which a processor with a virtual memory function manages a memory address space.

Microprocessors with a virtual memory function, first devised by Intel and now manufactured by various companies, are created with the idea of completely separating the memory space used for each task. It has a hardware structure in which each task has a descriptor table called LDT to manage the memory address space.

When managing using LDT, the descriptor is as follows:
At least, the start address of the used address space and the stored contents (for example, code) are registered and are of a fixed size of, for example, 8 bytes.

In this case, the number of descriptors corresponding to the basic elements of the task, such as program code, data, stack, etc., remains almost the same, but for example, some tasks load data from an external storage device into memory. Then, a request to increase the descriptor corresponding to this data occurs,
Also, if there is data to be saved to an external storage device, a descriptor deletion request is generated.

Therefore, the LDT storage area requires an area that can store the maximum number of descriptors that may increase, but the LDT storage area can be made as small as possible and memory usage efficiency can be improved. is desirable.

[Conventional technology]

A conventional example will be explained below using figures.

FIG. 3 is a block diagram of a conventional descriptor table management system.

In the conventional method, in order to easily manage the LDT, the LDT of each task is collected in a certain continuous area in memory, as shown in Figure 3, and each LDT is allocated to meet the maximum memory acquisition request during program execution. In consideration of the accompanying increase in descriptors, unused empty descriptors are prepared.

To explain FIG. 3, the descriptor table area has, for example, LDT areas 30, 31, and 32 for each task 1, 2, and 3, and each LDT area contains code segments necessary from the initial work.・Descriptor 40. Data segment descriptor 41. It has a stack segment descriptor 42 and free descriptor areas 43 to 4n that are registered according to the maximum memory acquisition request during program execution.

During program execution, when a memory acquisition request or a memory erase request occurs because the memory in use becomes unnecessary, the request analysis unit 4 of the descriptor processing unit 3' determines which task it belongs to, its contents, and how many descriptors are acquired. For example, if it is a 2-disc descriptor acquisition request for task l, the search/determination unit 5' searches for an empty descriptor area in the LDTel area 30 and determines whether it can be accommodated in this area. The registration/deletion unit 6' registers necessary contents in the determined free descriptor areas 43 and 44.

If it is an erasure request, search for the erasure request descriptor.
A determination unit 5' searches for the area, and a registration/deletion unit 6' erases that portion to create a free descriptor area.

In this way, the LDT for each task is collected in a certain continuous area on the memory, and the processor manages the descriptor table using the descriptor processing section 3'.

(Problem to be solved by the invention) L D T 6J [In terms of area, if a descriptor acquisition request in response to a memory acquisition request during program execution cannot be responded to, the system will go down, so it is necessary to respond to the acquisition request. However, in the conventional method described above, the LDT area is divided for each task, and each LDT requires an area with enough free descriptors to meet acquisition requests. Since it is a region, it occupies a large area in the memory, and there is a problem that the memory usage efficiency is poor.

[Means for solving problems]

The above problem can be solved by the principle block of the present invention shown in FIG.
When increasing the area 50 of T, a table processing means 2 is provided for copying the original LDT and writing the increased descriptor to the increasing area 51, and the processor manages the memory address space. This problem is solved by the descriptor table management method of the present invention.

[Effect]

When the descriptor cannot be increased, the table processing means 2 finds a free memory area 51 that can accommodate it, copies the original LDT and writes the increased descriptor to the area 51. by doing,
This eliminates the need for each LDT to have an area that can store the maximum possible number of descriptors.
As a result, the memory area used can be reduced, and memory usage efficiency can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 2 is a block diagram of a descriptor table management system according to an embodiment of the present invention.

In FIG. 2, the entire memory area 1 is data and code.

It can be used commonly for stacks, LDTs, etc.

Therefore, with reference to FIG. 2, a case will be explained in which, for example, the data entity 30 of task l increases and a request is made to increase the LDT 20 of the 3-disk scriber by 1 disk scriber.

The states of the entire memory area 1 shown in (a) and (b) indicate the state after a certain period of time, and the state changes from the state of a) to the state of (b), and the shaded area is an empty memory area.

When there is a request to acquire an l descriptor to the LDT 20 of the 3-disc scriber in task 1, the request analysis unit 4 analyzes this request and determines that it is from task 1, its contents, and that it is an acquisition request for 1-disc scriber. is analyzed and this fact is sent to the search/judgment section 5.

In the search/judgment section 5, the hunt section 7 of the table processing section 2
In the memory area 1 shown in FIG. The contents of the LDT 20 are copied here, and the new contents are registered in the registration/deletion section 6 for the added one disk descriptor, and the original LDT 20 portion is deleted and made into a free descriptor area.

The result obtained in this manner is shown in (b).

In the case of a deletion request, the request analysis section 4 analyzes the request, informs the search/judgment section 5 of the request, and sends the corresponding deletion portion of the LDT via the hunt section 7 of the table processing section 2. The descriptor area is searched and deleted by the registration/deletion unit 6 to become a free descriptor area.

In this way, in response to a descriptor increase request, the free area of the entire memory area l that can accommodate this is used as appropriate, so there is no need to make each LDTSI area an area that can accommodate the maximum descriptor increase request. , L
The memory area used as a DT can be made smaller and the memory can be used more effectively.

〔Effect of the invention〕

As explained in detail above, according to the present invention, in response to a descriptor increase request, the free area of the entire memory area l that can accommodate this is used appropriately, so each LD'r area can respond to the maximum descriptor increase request. Since there is no need to use a memory area, the memory area used as the LDT can be made smaller, and the memory can be used more effectively.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram of a descriptor table management system according to an embodiment of the invention, and FIG. 3 is a block diagram of a conventional descriptor table management system. In the figure, ■ is the entire memory area, 2 is the table processing section, table processing means, 3.3" is the descriptor processing section, 4 is the request analysis section, 5.5" is the search/judgment section, and 6.6" is the registration.・Delete section, 7 is hunt section, 8 is copy section, 10.11, 12.51 are free memory areas, 43 to 4n
indicates a free descriptor area, and 30.31.32.50 indicates a local descriptor table area. 3rd scarcity 2,1.

Claims (1)

[Scope of Claims] A descriptor table management method in which a processor manages a memory address space using a local descriptor table consisting of descriptors for each segment such as code, data, and stack for each task, comprising: storage of the local descriptor table; The area is the entire memory area (1), and the local descriptor table area (5) due to a descriptor increase request.
0), if it cannot be increased immediately, find a free memory area (51) within the total memory area (1) that can accommodate the increasing local descriptor table, and add the original local descriptor table to this area (51). - A descriptor table management system characterized by having table processing means (2) for copying the descriptor table and writing increased descriptors.