JPH10161932A - Disk cache control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the hit rate of disk cache and to shorten the input/output processing time. SOLUTION: When data for a user program 1 to request input are stored in a disk cache memory 7, these data are read out of the dish cache memory 7 and applied to the user program 1 by a cache control means 5 but when these data are not stored, they are read out of a file and applied to the user program 1. When it is judged while referring to input/output history information in the past to data in the file that possibility for data read out of the disk cache memory 7 to be inputted/outputted again is high the cache control means 5 improves the resident degree of these data in the disk cache memory 7. When the possibility for the data read out of the file to be inputted/outputted again is judged high, these data are stored in the disk cache memory 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a disk cache control method for controlling the degree of residence of data read from a file on a disk cache according to the characteristics of the file.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 64-82239 discloses that a file created on a magnetic disk is allocated with adjacent blocks in advance, and a file management system reads block data that does not exist in a disk cache. It describes that when requested, data of a requested block and a plurality of blocks adjacent to the requested block are read from a magnetic disk and stored in a disk cache.

[0003]

However, in the technique described in Japanese Patent Application Laid-Open No. Sho 64-82239, it is necessary to secure a group of adjacent blocks in a disk device in advance when creating a file and to allocate the block to the file. There is a problem that it is not easy to secure such close blocks in the apparatus.

[0004] Also, just because a request to read certain block data does not always follow a read request for block data adjacent to the block data, and if no read request follows, a block that is not read is not read. There is a problem that the group stays in the disk cache and the hit rate of the disk cache decreases.

An object of the present invention is to improve the hit rate of a disk cache and reduce the input / output processing time.

Another object of the present invention is to improve the hit rate of the disk cache by adjusting the degree of residence of the block data constituting the file on the disk cache based on the past access characteristics of the file. Another object is to reduce input / output processing time.

[0007]

According to a first disk cache control method of the present invention, a disk device for storing a file for inputting / outputting data in block units and a user for inputting / outputting the data between the file are provided. Program means, a disk cache memory for temporarily storing the data input / output between the file and the user program means, and the data requested by the user program means to be stored in the disk cache memory If the data has not been stored in the disk cache memory, the data is read from the file and the user program data is read from the file. Cache control means provided to the program means. In calculation system includes a file information management table for storing past output history information for said data in said file, said cache control means further with reference to the input history information,
When it is determined that there is a high possibility that the data read from the disk cache memory is input / output again, the resident degree of the data in the disk cache memory is increased.

According to a second disk cache control method of the present invention, in the first disk cache control method, the cache control means further refers to the input / output history information and stores the data read from the file. When it is determined that there is a high possibility of input / output again, the data is stored in the disk cache memory.

In a third disk cache control method according to the present invention, in the first or second disk cache control method, the cache control means further refers to the input / output history information to read data from the disk cache memory. If it is determined that there is a high possibility that other data in the file including the read data is also input / output, the resident degree of the other data in the disk cache memory is increased. .

According to a fourth disk cache control method of the present invention, in the second or third disk cache control method, the cache control means further reads out from the file with reference to the input / output history information. When it is determined that there is a high possibility that other data in a file including the data is also input / output, the other data is stored in the disk cache memory.

According to a fifth disk cache control method of the present invention, there is provided a disk device for storing a file for inputting / outputting data in block units, user program means for inputting / outputting the data to / from the file, A disk cache memory for temporarily storing the data input and output between the user program and the user program, and a disk cache for storing original data on the file replaced by the data requested by the user program for output. If it is also stored in memory,
A cache that replaces the original data on the disk cache memory and the file with the data, and replaces the original data on the file with the data when the original data is not stored in the disk cache memory. A computer system comprising a control unit and a file information management table for storing past input / output history information for the data in the file, wherein the cache control unit refers to the input / output history information, When it is determined that there is a high possibility that the data obtained by replacing the original data on the disk cache memory is input / output again, the degree of residence of the data in the disk cache memory is increased.

According to a sixth disk cache control method of the present invention, in the fifth disk cache control method, the cache control means further refers to the input / output history information to read only the original data on the file. If it is determined that there is a high possibility that the data obtained by replacing the data is input / output again, the data is written to the disk cache memory.

According to a seventh disk cache control method of the present invention, in the fifth or sixth disk cache control method, the cache control means further refers to the input / output history information and stores the data in the disk cache memory. If it is determined that there is a high possibility that other data in the file including the data that has replaced the original data is input / output, the degree of residence of the other data in the disk cache memory is increased. It is characterized by the following.

According to an eighth disk cache control system of the present invention, in the sixth or seventh disk cache control system, the cache control means further refers to the input / output history information and When it is determined that there is a high possibility that other data in a file including the data obtained by replacing only the original data is input / output, the other data is stored in the disk cache memory. I do.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Referring to FIG. 1, an embodiment of the disk cache control system of the present invention is a user program 1
A user memory 2, an input / output interface 3, a file management function 4, a cache control 5, a file information management table 6, a disk cache memory 7,
It comprises a cache memory management table 8, a disk device control function 9, and a disk device 10.

Next, the operation of the embodiment of the disk cache control system of the present invention will be described in detail with reference to FIG.

The user program 1 is stored in the disk device 10
To the input / output interface 3 to specify the name of the file stored in the file, the position in the file of the data to be input / output, and the address in the user memory 2 to perform the data transfer.

The input / output interface 3 converts the name of the file and the data position in the file into the block number in the disk device 10 among the input / output commands received from the user program 1, and sends it to the cache control function 5. hand over. The block number is a number indicating a position in the disk device 10 that is assigned to each block obtained by dividing an area in the disk device 10 into a certain size in ascending order.

The file management function 4 includes information on the position of blocks constituting each file on the disk device 10 and an access history indicating an input / output request issued to which block of which file and in which order. The information is stored in the file information management table 6 and managed.

The input / output interface 3 can obtain the information stored in the file information management table 6 by inquiring the file management function 4.

When the input / output command received from the input / output interface 3 is an instruction to input, that is, read from a file, the cache control function 5
It is determined whether or not the data of the block to be read is stored in the disk cache memory 7 by referring to the cache memory management table 8. If it is determined that the data is stored, the corresponding data is stored in the disk cache memory 7. If it is determined that the data is not stored in the disk cache memory 7, a disk device control command for reading the corresponding data from the disk device 10 is issued to the disk device control function 9. Then, the read data is transferred to the user memory 2.

At this time, the cache control function 5 refers to the access history information of the file information management table 6 and
If it is determined that the data read from the disk cache memory 7 is likely to be accessed again, the degree of residence of the data in the disk cache memory 7 is increased, and it is determined that the data is not likely to be accessed again. In this case, the resident degree of the data in the disk cache memory 7 is kept as it is. When it is determined that the data read from the disk device 10 is highly likely to be accessed again with reference to the access history information of the file information management table 6, the data is stored in the disk cache memory 7. If it is determined that there is no high possibility of being accessed again, the data is not stored in the disk cache memory 7.

Further, the cache control function 5 confirms that there is a high possibility that other data of the file including the data read from the disk cache memory 7 or the disk device 10 will be accessed. If the information suggests, the resident degree of the other data in the disk cache memory 7 is also increased or the other data is stored in the disk cache memory 7.

If the input / output command received from the input / output interface 3 is an instruction to output, that is, write data to a file, the cache control function 5 determines whether the block in the disk device 10 to which data is to be written is The cache memory management table 8 determines whether or not the data is already stored in the disk cache memory 7.
When it is determined that the data is stored, the data to be written is read from the user memory 2 and written to the disk cache memory 7 and the data is written to the corresponding block on the disk device 10. A disk device control command is issued to the disk control function 9.

At this time, the cache control function 5 refers to the access history information in the file information management table 6 and
If it is determined that the data written in the disk cache memory 7 is likely to be accessed again, the degree of resident of the data in the disk cache memory 7 is increased, and it is determined that the data is not likely to be accessed again. In this case, the resident degree of the data in the disk cache memory 7 is kept as it is.

If it is determined that the block in the disk device 10 to which data is to be written is not stored in the disk cache memory 7, the data to be written is read from the user memory 2 and the corresponding block in the disk device 10 is read. Then, a disk device control command is issued to the disk device control function 9 in order to write the data.

At this time, the cache control function 5 refers to the access history information in the file information management table 6 and
If it is determined that the data written to the disk device 10 is likely to be accessed again, the data is written to the disk cache memory 7 and if it is determined that the possibility of being accessed again is not high, The data is not stored in the disk cache memory 7.

Further, the cache control function 5 suggests that the access history information of the file information management table 6 indicates that there is a high possibility that other data of the file including the data written in the disk cache memory 7 will be accessed. In such a case, the resident degree of the other data in the disk cache memory 7 is increased or the other data is stored in the disk cache memory 7.

[0030]

Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 2 shows an embodiment in which a write request for file A on the disk device is issued.

In this embodiment, the file A is composed of five blocks. The blocks are A1, A2, A3, A4, A5 in order from the top of the file,
It is scattered on the disk device 10. Of these five blocks, A1 and A2 are the disk cache memory 7
Data is stored in the upper part, and the other areas of the disk cache memory 7 are all used by data of other files.

The file information management table 6 stores an access history indicating a certain number of past access histories indicating an input / output request for the file A and in which order the block is issued. According to the above, it is understood that a read request is always issued to each block of the file A immediately after data is written.

In this state, block A in file A
It is assumed that a data write request has been issued to Nos. 3 and A4. Since these blocks are not stored in the disk cache memory 7 and have not been accessed within a certain period in the past, it can be said that their use frequency is low at the present time. However, according to the access history of the other blocks of the file A to which the two blocks belong, it can be understood that a read request for the same block has occurred immediately after the writing of data to a certain block has occurred. Similarly, it can be determined that there is a high possibility that reading is requested for the blocks A4 and A4.

Such an access history for each file is stored in the file information management table 6 in FIG. 1, and can be referred to by the cache control function 5 making an inquiry to the file management function 4.

The cache control function 5 determines, based on the above judgment, the blocks A3 and A4 for which a write request has been issued.
Is written to the disk device and is also stored in the disk cache memory 7, and the least frequently used block among the blocks currently stored in the disk cache memory 7 is deleted.
And A4.

Thereafter, when a data read request is issued to the block A3 or A4, it is necessary to access the disk device 10 because the data of these blocks is stored in the disk cache memory 7. Therefore, data transfer to the user memory 2 can be performed at high speed.

FIG. 3 shows an embodiment in which a data read request for file B on the disk device is issued.

In this embodiment, the file B is composed of six blocks. The block is B1, B2
B3, B4, B5, B6, which are scattered on the disk device 10. All of these six blocks have data stored in the disk cache memory 7 and can transfer data without accessing the disk device 10 in response to a read request from the user program 1. However, the priority is lowered because access has not been performed for a relatively long time as compared with other blocks in the disk cache memory 7, and when it becomes necessary to store a new block in the disk cache memory 7 next time, Instead, it is assumed that the block is a candidate for a block to be deleted. Such information is stored in the cache memory management table 8 in FIG.

The file information management table 6 stores an access history as an input / output request issued to the file B for a fixed number of times in the past. It can be seen that the request is a request and the access is sequentially from B1 which is the first block of the file to B6 which is the last block.

In this state, block B in file B
Assume that a data read request has been issued for No. 1. Since the block B1 has data in the disk cache memory 7, the data can be transferred to the user memory 2 without accessing the disk device 10. At the same time, the cache control function 5 raises the priority of B1 because there has been access to B1 which has been a candidate for a block to be deleted because of its low usage frequency.

Further, the cache control function 5 inquires of the file management function 4 that the data read request for the file B is highly likely to be made by sequential access from the first block of the file, and the remaining of the file B is It is determined that a read request will be issued to the blocks B2 to B6 soon. As a result, before access to the blocks B2 to B6 has not yet occurred, the information in the cache memory management table 8 is updated, and the priority of the blocks B2 to B6 is increased so that the blocks B2 to B6 are not immediately deleted from the disk cache memory 7. deep.

Thereafter, if the file B is sequentially accessed and a data read request is issued to the blocks B2 to B6, those blocks are still stored in the disk cache memory 7 with a high probability. Since it is left as it is, data transfer to the user memory 2 can be performed at high speed without accessing the disk device 10.

[0044]

As described above, the present invention adjusts the resident level of the block data constituting a file on the disk cache based on the past access characteristics of the file, thereby achieving the hit of the disk cache. This has the effect of improving the rate and shortening the input / output processing time.

[Brief description of the drawings]

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

FIG. 2 is a diagram for explaining processing when a data write request for a file on a disk device is issued in the embodiment of the present invention.

FIG. 3 is a diagram for explaining processing when a data read request for a file on a disk device is issued in the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 User program 2 User memory 3 I / O interface 4 File management function 5 Cache control function 6 File information management table 7 Disk cache memory 8 Cache memory management table 9 Disk unit control function 10 Disk unit

Claims (8)

[Claims] 1. A disk device for storing a file for inputting / outputting data in block units, a user program unit for inputting / outputting the data to / from the file, and an input / output between the file and the user program unit. A disk cache memory for temporarily storing the data to be output, and, if the data requested by the user program means to be input is stored in the disk cache memory, read the data from the disk cache memory Wherein the data is not stored in the disk cache memory, the data is read from the file and the cache control means is provided to the user program means. For the data in the file A file information management table for storing past input / output history information, wherein the cache control unit can further input / output the data read from the disk cache memory with reference to the input / output history information A disk cache control method for increasing the degree of resident of the data in the disk cache memory when it is determined that the data is high. 2. When the cache control unit further determines that the data read from the file is highly likely to be input / output again with reference to the input / output history information, the cache control unit deletes the data. 2. The disk cache control method according to claim 1, wherein the data is stored in the disk cache memory. 3. The cache control unit may further refer to the input / output history information to input / output other data in a file including the data read from the disk cache memory. 3. The disk cache control method according to claim 1, wherein when it is determined to be high, the resident degree of the other data in the disk cache memory is increased. 4. The method according to claim 1, wherein the cache control unit further refers to the input / output history information and has a high possibility of inputting / outputting other data in a file including the data read from the file. 4. The disk cache control method according to claim 2, wherein when the determination is made, the other data is stored in the disk cache memory. 5. A disk device for storing a file for inputting / outputting data in block units, user program means for inputting / outputting the data to / from the file, and input / output between the file and the user program means. A disk cache memory for temporarily storing the output data; and a case where the original data on the file replaced by the data requested by the user program means is also stored in the disk cache memory. Replacing the original data on the disk cache memory and the file with the data, and replacing the original data on the file with the data if the original data is not stored in the disk cache memory. Computer system with cache control means A file information management table for storing past input / output history information for the data in the file, wherein the cache control unit further refers to the input / output history information, and A disk cache control method, wherein when it is determined that there is a high possibility that the data obtained by replacing the original data is input / output again, the resident degree of the data in the disk cache memory is increased. 6. When the cache control unit further determines with reference to the input / output history information that the data obtained by replacing only the original data on the file is likely to be input / output again. 6. The disk cache control method according to claim 5, wherein said data is written to said disk cache memory. 7. The cache control unit further refers to the input / output history information to input / output other data in a file including the data obtained by replacing the original data on the disk cache memory. 7. The disk cache control method according to claim 5, wherein when it is determined that there is a high possibility that the data is deleted, the resident degree of the other data in the disk cache memory is increased. 8. The cache control unit further refers to the input / output history information to input / output other data in a file including the data obtained by replacing only the original data in the file. 8. The disk cache control method according to claim 6, wherein the other data is stored in the disk cache memory when it is determined that there is a high possibility that the data is stored.