JPH0264832A - Disk cache memory control device - Google Patents

Abstract

PURPOSE:To prevent an adverse influence from being given to the performance of a whole computer system by sorting a disk cache memory area in the order of the high frequency of access with respect to a data block stored in the area. CONSTITUTION:A chain of control information is constituted by using two pieces of information in a position on the main storage device of the computer system in a control information area corresponding to the disk cache memory which is precedingly positioned in the order relation of the access frequency that is stored in a storage area 1, and a position on the main storage device which is succeedingly positioned by the order relation of the access frequency that is stored in a storage area 2. The chain is controlled so that the data blocks stored in the corresponding areas are sorted in a descending order form the high frequency of access to the low frequency. Thus, the adverse influence is prevented from being given to the performance of the whole computer system.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a disk cache memory management device that speeds up access in a randomly accessible low-speed auxiliary storage device, and in particular, to a disk cache memory management device that speeds up access in a low-speed auxiliary storage device that can be randomly accessed. The present invention relates to a disk cache memory management device that increases speed.

[Prior Art] A magnetic disk device, which is an auxiliary storage device, performs data access - times by dividing it into blocks of a specific size, and randomly accesses any data block on the storage medium. However, the access speed is slow. For this reason, computer systems using such slow storage media use disk cache memory to speed up randomly generated accesses to arbitrary data blocks stored in the auxiliary storage. is being used.

This disk cache memory always holds data stored in data blocks corresponding to data access units to a finite number of auxiliary storage devices in a specific area of the computer's main storage device. When a data block stored in auxiliary storage is accessed, the contents of the data block held in a specific area on this main storage are Checks whether the required data block exists, and if so, accesses the data block held in a specific area on main storage without accessing auxiliary storage. This is what we do.

By the way, the conventional disk cache memory management device provides a management information area corresponding to the cache memory area corresponding to each data block, and stores the data stored in the corresponding cache memory in the management information area.
Sets the time the block was read from auxiliary storage. Thereafter, each time an access to the corresponding data block occurs, the access count stored in the management information area is updated, and the frequency of access to the corresponding data block is always displayed in the management information area. It holds the basic information for calculating.

Additionally, if a new data block that is not stored in the disk cache memory is accessed while all areas on the disk cache memory are in use, this new data block When selecting space for storing individual disks,
Data blocks stored in the cache memory stored in the management information area corresponding to the cache memory area are transferred from the auxiliary storage device to the disk cache.
Calculates the access frequency of the corresponding data block based on two pieces of information: the time it was read into the memory area and the number of accesses to that data block, and then calculates it from among all disk cache memory areas. The area that stores the data blocks that are least frequently accessed is selected, and new blocks are stored in that area.

[Problems to be solved] Two conventional disk cache memory management devices do not store data on the disk cache memory when all areas on the disk cache memory are in use. When a new data block is accessed, management information areas corresponding to all disk cache memory areas are searched to select a disk cache memory area to store the data block. , the number of accesses to the individual data blocks stored therein, and the data
It was necessary to calculate the frequency of access to a data block based on the time the block was read from the auxiliary storage device into the disk cache memory area. However, searching for the management information area corresponding to all disk cache memory areas increases the overhead as the number of disk cache memory areas increases, which has a negative impact on the performance of the entire computer system. There was a problem with giving. This is particularly true for computer systems that use central processing units with relatively low processing power, such as microprocessors.

Furthermore, since time information is used as described above, there is also the problem that it cannot be adopted in small-scale computer systems that do not have a clock.

The present invention has been made in view of the above-mentioned problems, and provides disk cache memory management that does not adversely affect the performance of the entire computer system even when the number of disk cache memory areas increases. The purpose is to provide equipment.

[Means for solving problems] In order to achieve the above object, the disk cache memory management device of the present invention
access frequency order relationship information storage means for storing information representing an order relationship according to the access frequency of the data block in the management information of the memory area; an access frequency order relation information update means for updating an access frequency order relation in which the access frequency order relation exists; and a new data block that is not stored on the disk cache memory in a situation where all areas on the disk cache memory are in use. When access occurs, select the lowest order in the disk cache memory area,
After actually reading the data block, the data block is stored in the management information area with the lowest order relationship.

With this configuration, disk cache,
When all memory space is in use, the disk
When a new data block that is not stored in the cache memory is accessed, each data block is stored between the individual disk cache memory areas in which it is stored. An ordering relationship is established based on the frequency of access to a data block, without using information that quantitatively represents the time elapsed since the data block was stored in the disk cache memory, such as access time. , - This ordering relationship is updated every time a data block is accessed, and all disk cache memory areas on the disk cache memory are allocated to the most frequently accessed data blocks stored there. If a new data block that is not stored in the disk cache memory is accessed in a situation where all the areas on the disk cache memory are in use by sorting the data in order, the data will be accessed. - Select the last one in the sorting list as the disk cache memory area for storing the block.

[Example] Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a configuration diagram of a management information area corresponding to a disk cache memory area in a disk cache memory management device according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a storage area for information (previous information) indicating the position on the main storage device of the computer system of the management information area corresponding to the disk cache memory area located immediately before in the order of access frequency; 2 is information indicating the position on the main storage device of the computer system of the management information area corresponding to the disk cache memory area located immediately after the disk cache memory area in the order of access frequency (immediate information)
3 is a storage area for information identifying data blocks stored in the corresponding disk cache memory area (data block identification information); 4 is a storage area for the computer system in the corresponding disk cache memory area. This is a storage area for information (address information) representing a location on the main storage device.

The location on the main storage device of the computer system of the management information area corresponding to the disk cache memory area located immediately before in the order of access frequency stored in storage area 1, and the access stored in storage area 2. The chain of these management information is created using two pieces of information: the location on the main storage of the computer system of the management information area corresponding to the disk, cache, and memory area that is located immediately after the disk in the order of frequency. This chain is managed so that it is always sorted according to the access frequency of the data blocks stored in the respective disk cache memory areas.

Next, FIG. 2 shows the disk cache memory management system in the disk cache memory management device of FIG.
FIG. 3 is a diagram showing memory management information.

In the figure, numerals 5 to 9 are management information corresponding to disk cache memory areas, which are linked in order of access frequency from highest to lowest.

In the initial state, there is no management information area corresponding to the disk cache memory area that constitutes this management information. It is assumed that this management information includes management information areas corresponding to all disk cache memory areas when all areas on the disk cache memory are in use. To process accesses to new data blocks that occur until this state is reached, the free disk cache memory area is used and the data blocks necessary for that area are read from the auxiliary storage device. After storing, data is set in the management information area corresponding to the area, and the management information is added to the position indicated by management information 9.

When a data block stored in disk cache memory is accessed, the disk cache that stores the required data block is accessed regardless of whether there is free space in the disk cache memory area. - If the management information area corresponding to the memory area is located in management information 5 at the agricultural level in the management information,
Assume that the disk cache memory area is simply accessed.

On the other hand, if the management information area corresponding to the disk cache memory area storing the required data block is located in 6 to 9 of the disk cache memory management information, that disk cache memory area At the same time, the contents of storage areas 1 and 2 in FIG. 1 are updated in order to access the management information and replace the location of the management information in the disk cache memory management information with that of another location. By performing this process every time a data block stored on the disk cache memory is accessed, it corresponds to the disk cache memory area that constitutes the disk cache memory management information 5 to 9. The chain of management information areas is sorted in descending order of access frequency to the data blocks stored in the disk cache memory area corresponding to each management information area.

In addition, if the disk cache memory area is all in use and a new data block that is not stored in the disk cache memory is accessed, the disk cache memory management information 5 to 9 As mentioned above, the disk cache memory management information 5 is used as the disk cache memory area for storing newly required data blocks.
It is possible to easily select the area for the disk cache memory area management information located at the position of the management information 9 that stores the least frequently accessed data block among the data blocks 9 to 9.

In this way, in this embodiment, the disk cache memory management method in the disk cache method is such that each data block is stored between the individual disk cache memory areas where each data block is stored. An ordering relationship is established based on the frequency of access to the data blocks in the data block, and this ordering relationship is updated each time the data block is accessed - times, and all disk cache memory areas on the disk cache memory are Sort the data blocks stored therein in order of the most frequently accessed data blocks, and sort all the disks in the disk cache memory.
When a new data block that is not stored in the disk cache memory is accessed while the cache area is in use, it is used as a disk cache memory area to store that data block. , a method is adopted in which the last item in a certain sequence is selected through sorting.

[Effects of the Invention] As explained above, the present invention not only simplifies the conventionally complicated and inefficient disk/cache/memory management processing, but also enables small-scale processing using a central processing unit with relatively low processing power. A disk cache system that can speed up access to auxiliary storage devices using an efficient disk cache method even in modern computer systems.
This has the effect of providing a memory management device.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a management information area corresponding to a disk cache memory area in a disk cache memory management device according to an embodiment of the present invention, and FIG.
FIG. 3 is a diagram showing chained disk cache memory management information in the disk cache memory management device shown in the figure. 1-4: Storage area 5-9: Disk cache memory management information chart in order of access frequency

Claims (1)

[Claims] an access frequency order relationship information storage means for storing information representing the order relationship according to the access frequency of the data block in the management information of each disk cache memory area; an access frequency order relationship information update means for updating the access frequency order relationship stored in the information area;
If a new data block that is not stored in the disk cache memory is accessed while all areas on the cache memory are in use,
and area selection means for selecting the lowest order relation among the disk cache memory areas, and after actually reading the data block, storing the data block in the management information area with the order relation being the lowest order. A disk cache memory management device characterized by: