JPH05334173A - Memory management system - Google Patents

Abstract

PURPOSE:To efficiently manage an idle buffer by dually managing a buffer pool. CONSTITUTION:Usable buffer pools are divided into a usable buffer pool and a buffer pool to be used after writing and the usable buffers are successively searched from a buffer management table 1. At first a buffer 2p is detected and extracted from the usable buffer pool. Since the buffer 2p has a usable mark, a process uses the buffer 2p. In the case of releasing the buffer 2p, a using mark put on the buffer 2p is changed to a usable mark, and when a writing mark is put on the buffer 2p, the buffer 2p is returned to a buffer 3 to be used after writing. When a writing mark is not put on the buffer 2p, the buffer 2b is returned to the usable buffer pool 1.

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 managing a buffer provided on a main memory of a computer system, for example.

[0002]

2. Description of the Related Art Conventionally, as this type of system, for example, Ma
Urice J. There was one shown in "Design of UNIX Kernel" by Bach, page 32 (UNIX is a registered trademark of AT & T).

FIG. 4 is a block diagram showing a conventional buffer management system. In the figure, 1 is an available buffer management table for managing available buffers, 2a, 2
p, 2k are available buffers, 2c, 2d, 2e, 2
Reference numerals h, 2i, 2j, 2m, 2n, and 2o indicate buffers currently in use, and 2L, 2b, 2f, and 2g indicate buffers that can be used after writing to the external storage device. Reference numeral 3 indicates an available buffer pool.

In the system having such a configuration, buffer acquisition is performed based on the step diagram shown in FIG.

In step 1, the available buffer pool 3 is searched sequentially from the available buffer management table 1. Since we first found buffer 2L, we skip step 2 and proceed to step 3. In step 3, the buffer 2L is taken out from the available buffer pool 3. That is, the buffer 2L is deleted from the available buffer management table 1. Since the buffer 2L is marked for writing, the data stored in the buffer 2L is written in the external storage device in step 4, and the process returns to step 1.

Returning to step 1, the available buffer pool 3 is searched again from the available buffer management table 1. Since the buffer 2L has been deleted from the buffer management table 1 in the first search, this time the buffer 2p is first deleted.
Can be found. Since the buffer is found, the process jumps to step 3, and the buffer 2p is deleted from the available buffer management table 1. Since the buffer 2p is marked as available, the process that has acquired the available buffer uses the buffer 2p.

The process using the buffer 2p releases the buffer based on the step diagram shown in FIG. In step 1, the in-use mark attached to the buffer 2p is changed to available. In step 2, the buffer 2p is returned to the available buffer pool 3. That is, it is registered in the available buffer management table 1. Even if the process has marked the buffer 2p for writing, the buffer is released by the same process.

[0008]

In the conventional buffer management system, the available buffer and the buffer available after writing are mixed and managed in the available buffer pool 3 in a unified manner as described above. If a process acquires a buffer and it is available after writing, the data stored in the buffer can be written to the external storage device and then used again from the beginning. I had to find a buffer, which was a very inefficient problem.

The present invention has been made to solve the above problems, and an object thereof is to obtain a memory management system capable of efficiently accessing a memory.

[0010]

In the buffer management device according to the present invention, for example, the available buffer pool is divided into two, that is, the available buffer pool and the buffer pool that can be used after writing, and the buffer pool is binaryly divided. It is managed and has the following elements. (A) A first area management unit that manages an available memory area in the memory area, and (b) a second area management unit that manages an available memory area in the memory area after a predetermined process. Means, (c) Acquisition means for acquiring one memory area from the memory area managed by any one of the first and second area management means.

[0011]

In the memory management system configured as described above, the first area management means manages the usable memory area, and the second area management means manages the usable memory area after writing. Let Then, when acquiring the memory area, the available memory area managed by the first area managing means is first acquired, and, for example, the usable memory area after writing managed by the second area managing means is acquired. The available memory area can be acquired without being lost.

[0012]

【Example】

Example 1. FIG. 1 is a block diagram showing an embodiment of the present invention. 1, 2a to 2o and 3 are exactly the same as those in the conventional system. Reference numeral 4 is a write buffer management table for managing buffers that can be used after writing. Reference numeral 5 indicates a buffer pool that can be used after writing. Further, 10 is a first area management unit that manages a memory area that can be immediately used in the memory area, and 20 is a memory area other than the memory area that is managed by the first area management unit. Second area management means for managing a memory area that can be used after the acquisition, and 30 is acquisition means for acquiring one memory area from the memory area managed by any one of the first and second area management means. is there.

In the memory management system having such a configuration, the buffer is acquired based on the step diagram shown in FIG.

In step 1, the available buffer pool 3 is searched sequentially from the available buffer management table 1. First I found buffer 2p, so step 2,
Step 3 skips to step 4. In step 4, the buffer 2p is taken out from the available buffer pool 3.
That is, available buffer management table 1 to buffer 2
delete p. Since the buffer 2p is marked as available, the process that came to acquire the available buffer uses the buffer 2p.

The process using the buffer 2p releases the buffer based on the step diagram shown in FIG. In step 1, the in-use mark attached to the buffer 2p is changed to available. Buffer 2p in step 2
If it is marked to be written, the buffer 2p is returned to the available buffer pool 5 after writing. If the buffer 2p is not marked for writing, the buffer 2p is returned to the available buffer pool 3.

As described above, according to this embodiment, the data stored in the external magnetic storage device is stored in the buffer cache on the main storage via the external storage control device, and the data read instruction from the central processing unit is issued. In a buffer management method that enables a fast response to, a first buffer pool that stores each available buffer and a second buffer pool that stores an available buffer after writing are provided. Alternatively, it is characterized by comprising means for acquiring an available buffer from the second buffer pool and means for releasing an unnecessary buffer to the first or second buffer.

Then, as described above, the available buffer pool is divided into the available buffer pool and the buffer pool that can be used after writing, and the buffer pool is dually managed to obtain a free buffer. Can be done efficiently.

The process of writing back the cache data to the disk occurs in the following four cases. 1. If there is no buffer available in the cache area, write the buffer contents back to disk and free the buffer. 2. When you remove a disk, write back the contents of the buffer corresponding to that disk. 3. Synchronous request from the user (makes all buffer contents the same as the corresponding disk contents). 4. The OS requests synchronization at equal time intervals. In the case of the synchronous requests of 3 and 4 above, in the conventional technique, an available buffer pool (a large size buffer pool)
Had to find a buffer to write back from and process it. On the other hand, according to this embodiment, since the contents of the buffer in the buffer pool that can be used after writing should be returned when synchronizing, there is an advantage that the response to the synchronization request can be made efficiently.

Example 2. In the first embodiment, the buffer management in which the data stored in the external magnetic storage device is stored in the buffer cache via the external storage control device and the data from the central processing unit can be responded to the read command at high speed. However, the management may be performed not only in the cache memory and the buffer but also in other memory. Further, the memory is not limited to a volatile memory such as a main memory, but may be a non-volatile memory such as a magnetic disk.

Example 3. Further, although not particularly mentioned in the first embodiment, the size of each memory area constituting the memory may be divided into predetermined units such as 1 byte or 1 bit, or the predetermined units may be used. It may be of any length without being delimited.

Example 4. In the first embodiment described above, the case in which the first buffer pool storing each available buffer and the second buffer pool storing the buffer available after writing are provided is described. What is stored in the pool does not have to be a buffer that can be used after writing, and it is sufficient that a buffer having different access efficiency from that of the usable buffer stored in the first buffer pool is stored.

[0022]

As described above, according to the present invention, a usable memory area can be efficiently acquired from a plurality of memory areas.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a step diagram of buffer acquisition showing an embodiment of the present invention.

FIG. 3 is a step diagram of buffer release showing an embodiment of the present invention.

FIG. 4 is a buffer configuration diagram showing a conventional buffer management system.

FIG. 5 is a step diagram showing a conventional buffer acquisition method.

FIG. 6 is a step diagram showing a conventional buffer release method.

[Explanation of symbols]

1 Available buffer management table 2a, 2p, 2k Available buffer 2c, 2d, 2e, 2h, 2i, 2j, 2m, 2n, 2
o In-use buffer 2L, 2b, 2f, 2g Usable buffer after writing 3 Usable buffer pool 4 Write buffer management table 5 Usable buffer pool after writing 10 First area management means 20 Second area management means 30 Acquisition means

Claims (1)

[Claims] 1. A memory management system comprising a plurality of memory areas for storing data and having the following elements: (a) first area management means for managing available memory areas among the memory areas; ) A second area management means for managing a memory area that can be used after a predetermined process in the memory area, and (c) a memory area managed by any one of the first and second area management means. Acquisition means to acquire one memory area.