JP2665180B2 - Disk cache buffer allocation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for securing a disk cache buffer, and more particularly to a method for securing a disk cache buffer in a file system for managing file I / O.

[0002]

2. Description of the Related Art Generally, a disk cache buffer is an I / O for a magnetic disk device secured on a memory.
This is a dedicated data buffer for (Input / Output: input / output). When data is read from the magnetic disk device, if the target data exists in the disk cache buffer, the data is read therefrom. Further, at the time of data writing, access to the magnetic disk device (hereinafter, referred to as disk access) is not performed by writing to the disk cache buffer on the memory. Such a disk cache buffer is used for the purpose of improving system processing performance.

Next, a conventional method for securing a disk cache buffer will be described with reference to the drawings.

FIG. 5 is a configuration diagram of an information processing system for explaining an example of a conventional method of securing a disk cache buffer. This information processing system includes a user application 1 and a file management system in a magnetic disk device. And a magnetic disk device 7. The file system 2 has a file I / O management unit 3 for performing file access in response to a request from the user application 1, a disk cache buffer 4 for holding user data, and a magnetic disk in response to a request from the file I / O management unit. A disk I / O unit 6 for accessing the disk device and an initialization unit 10 for initializing information necessary for the operation of the file system are provided. The initialization unit 10 secures a memory for a disc cache buffer. To secure the disk cache buffer to perform Also, the magnetic disk drive 7
Has a built-in data buffer 8 as an I / O dedicated buffer and a magnetic disk 9 as a magnetic recording medium.

Next, with reference to FIGS. 6, 7, 8 and 9, a description will be given of a method of securing a disk cache buffer in a conventional report processing system.

FIG. 6 is a flow chart showing the flow of the operation of the initialization processing in the conventional system, FIG. 7 is a flow chart showing the flow of the operation of the file I / O management means 3 of FIG. 5, and FIG. FIG. 9 is a configuration diagram showing the configuration of the disk cache buffer 4 shown in FIG. 5, and FIG. 9 is an operation diagram illustrating a conventional disk cache buffer reservation system.

First, referring to FIG. 6, the initialization processing means 10 of the file system 2 executed when the system is started up.
Secures a memory required for the disk cache buffer 4 (S11). In this securing process, the disk cache buffer capacity is calculated from the cache segment size and the number of cache segments set as the system prescribed values, and the capacity is secured.

The cache segment in this case is shown in FIG.
As shown in (1), it means a division unit of the entire disk cache buffer, and is composed of a segment size: m bytes and the number of segments: n, and disk access is performed in units of this segment.

The disk cache buffer 4 secured by this initialization process is resident on the memory until the system is terminated. Then, after the system is started, a data read or write request (hereinafter referred to as a data read / write request) generated from the application 1 is:
The information is transmitted to the file system 2 and received by the file I / O management unit 3.

Next, referring to FIG. 6, file I / O
The management means 3 searches whether or not the target data exists in the disk cache buffer 4 (S21). As a result of the search, if the target data exists in the disk cache buffer 4 (S22), a read (read) or a write (write) is executed for the cache segment (S23).

In S22, if the target data does not exist in the disk cache buffer 4, an unused cache segment is searched. If there is an unused cache segment (S24), the unused cache segment is searched. To read (read) or write (write) the magnetic disk device 7 via the disk I / O means 6 (S26).

If there is no unused cache segment in S24, the cache segment that has been accessed for the longest time since being accessed is searched for among the used cache segments. Then, the data of the cache segment is also discharged to the magnetic disk device 7 by the disk I / O means 6 (S25), and is read and used as a cache segment for the target data in the same manner as when there is an unused cache segment. Alternatively, a write is executed (S26).

At this time, in S25, the data discharged from the cache segment is written to the data buffer 8 in the disk device 7. If all of the data buffers 8 are in use at this point, the data is recorded on the magnetic disk 9. Note that, like the disk cache buffer 4, the data buffer 8 is divided into a plurality of cache segments. Thereafter, the file I / O management unit 3 notifies the request source application of the completion of the processing.

Next, an example of a method of using the disk cache buffer will be described with reference to an operation diagram shown in FIG.

First, the cache segments (number: 200, segment size: 1K) in the file system 2
B, total 200 KB) holds requested user data a, b, c, d,... The data buffer (number: 2, size 10K) in the magnetic disk device 7
B) also holds data A and B used in the past, respectively. In this case, the user data v, x, z (each 1K
When the write request of B) occurs, the file system 2
Since all of the cache segments in are in use,
User data is discharged in the order of a, c, and b.

Therefore, A of the data buffer in the magnetic disk device writes A to the magnetic disk medium in order to receive the user data a from the cache segment (in the figure). Then, in order to receive the user data c, the data buffer B in the magnetic disk device 7 is written to the magnetic disk medium (in the figure). In order to receive the user data b, the user data a is written on the magnetic disk 9 (in the figure).

As a result, in the cache segment in the file system 2, the user data v, x, z,
.. exist, and user data b and c exist in the data buffer in the magnetic disk device 7. The I / O processing to the magnetic disk device 7 accompanying this processing is performed three times.

[0018]

In the conventional disk cache system described above, if the size of the cache segment in the file system is smaller than the data buffer size in the magnetic disk device, the data buffer cannot be used efficiently. There are drawbacks.

For example, referring to FIG. 9, there is a problem in writing the user data z. The writing of the cache segment b generated by this writing involves a process of writing the data (1 KB) of the user data a in the data buffer to the magnetic disk A.

Here, originally, the user data a, b
Are consecutive data, and therefore should be held in A of the data buffer at the same time. However, since one data buffer is allocated to one input / output process from the file system, it is not batch-processed as discontinuous data.

As a result, 10 KB for 1 KB of valid data
A data buffer of KB is allocated, and invalid data of 9 KB is also handled at the same time. Therefore, the data buffer cannot be used effectively, and disk access frequently occurs, resulting in a decrease in system performance.

An object of the present invention is to solve such a disadvantage and to provide a more efficient and high-performance information processing system.

[0023]

SUMMARY OF THE INVENTION The present invention relates to a method for reserving a disk cache buffer in an information processing system including a magnetic disk device having a built-in data buffer and a file system having a disk cache buffer. A connection disk recognizing means for recognizing a disk device, disk-based cache buffer information storing information including a model number of the magnetic disk device and a cache segment size, and a model number of the magnetic disk device obtained by the connection disk recognizing means. A disk cache buffer reserving means for retrieving the disk-specific cache buffer information and reserving a memory required for the disk cache buffer from the obtained cache segment size.

[0024]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an information processing system for realizing an embodiment of a method for securing a disk cache buffer according to the present invention. The information processing system according to the present embodiment includes:
As shown in FIG. 1, the initialization processing means 5 of the file system 2 recognizes a magnetic disk device to be connected and sets an optimum cache segment size by using a connection disk recognition process 5a and a connection disk recognition process. It has disk-specific cache buffer information 5b and a disk cache buffer securing process 5c for securing a memory for a disk cache buffer. The rest of the configuration is the same as the conventional one.

The user application 1, the file system 2, the file I / O management means 3, the cache buffer 4, the disk I / O means 6, the magnetic disk device 7, the data buffer 8 and the magnetic disk 9 The configuration is the same as that of the information processing system, and the same reference numerals as those of the information processing system shown in FIG. The disk cache buffer securing processing 5c in the initialization processing means 5 has the same function as the initialization processing means 10 shown in FIG.

Next, referring to FIGS. 2, 3 and 4, a description will be given of a method of securing a disk cache buffer according to the present invention.

FIG. 2 is a flow chart showing the flow of the operation in the initialization processing means 5 in FIG. 1, and FIG. 3 is a configuration diagram showing the configuration of cache buffer information for each magnetic disk device according to the present invention. FIG. 4 is an operation diagram illustrating a method for securing a disk cache buffer in the information processing system of the present invention.

First, referring to FIG. 2, in the file system 2 initialization processing means 5 executed when the system is started, a connection disk recognition processing 5a for recognizing a magnetic disk device to be connected is performed. The model number of the magnetic disk device 7 connected via the / O means 6 is obtained (S1). Next, based on the disk model number obtained in this recognition processing, a corresponding cache segment size is searched and obtained from the disk-specific cache buffer information 5b including the disk model number and the cache segment size shown in FIG. 3 (S2).

Subsequently, a disk cache buffer securing process 5c for securing a memory required as the disk cache buffer 4 is performed using the determined cache segment size (S3). In this securing process, the cache buffer capacity is calculated based on the obtained cache segment size and the number of cache segments, and the amount corresponding to the capacity is secured.

Since the maximum cache buffer capacity is constant, the number n of cache segments conventionally set as a system-specified value is a variable value obtained by dividing the maximum cache buffer capacity by the cache segment size.
When these are expressed by formulas, cache buffer capacity = (cache segment size m) × (cache segment number n) cache segment number n = (maximum cache buffer capacity) ÷ (cache segment size).

Further, the processing in the file system 2 from the application 1 until the data read / write request is executed after the system is started and is completed is the same as that of the conventional system. Although omitted, the operations of the cache segment in the file system 2 and the data buffer 8 in the magnetic disk device 7 are different from those of the conventional system.

Next, a method of using the disk cache buffer according to the present invention will be described with reference to the operation diagram of FIG.

First, the cache segments in the file system 2 (number: 20, segment size: 10K)
B) holds the requested user data a to k, l to u. The data buffer (number: 20, segment size: 10 KB) in the magnetic disk device 7
Data A and B used in the past are stored. In this case, when a write request for the user data v, x, z (1 KB each) occurs, all of the cache segments in the file system 2 are in use, and the segments a to k used most recently are discharged. Is done.

Thus, the data buffer A in the magnetic disk device 7 writes A to the magnetic disk to receive the cache segments a to k (in the figure).
Then, a cache segment for the user data v is allocated. Further, the user data x and z are also recorded in the same cache segment as v with the segment size of 10 KB. As a result, the user data v to z are stored in the disk cache buffer 4 in the file system 2.
And user data a to k and B exist in the data buffer 8 in the magnetic disk device 7.
Further, the I / O processing to the magnetic disk device 7 accompanying this processing is performed only once.

[0036]

As described above, according to the disk cache buffer securing method of the present invention, since the size of the cache segment in the file system is the same as the size of the data buffer in the magnetic disk device, data can be efficiently stored. The buffer can be utilized, and the number of times of writing from the data buffer to the magnetic disk device can be reduced. Therefore, there is an effect that an efficient and high-performance information processing system can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an information processing system for realizing a disk cache buffer securing method according to the present invention.

FIG. 2 is a flowchart showing a flow of an operation in an initialization processing means 5 of FIG. 1;

FIG. 3 is a configuration diagram showing a configuration of cache buffer information for each magnetic disk device according to the present invention.

FIG. 4 is an operation diagram illustrating a method for securing a disk cache buffer according to the present invention.

FIG. 5 is a configuration diagram showing an information processing system for explaining a conventional method of securing a disk cache buffer.

FIG. 6 is a flowchart showing an operation flow of an initialization process in a conventional method.

7 is a flowchart showing an operation flow of the file I / O management means 3 of FIG.

8 is a configuration diagram showing a configuration of a disk cache buffer 4 of FIG.

FIG. 9 is an operation diagram illustrating a method of securing a disk cache buffer according to a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 User application 2 File system 3 File I / O management means 4 Disk cache buffer 5, 10 Initialization processing means 5a Connection disk recognition processing 5b Disk-specific cache buffer information 5c Cache buffer reservation processing 6 Disk I / O means 7 Disk device 8 Data buffer 9 Magnetic disk

Claims (1)

(57) [Claims] 1. A method for reserving a disk cache buffer in an information processing system including a magnetic disk device having a built-in data buffer and a file system having a disk cache buffer, wherein the connection disk recognition recognizes the magnetic disk device to be connected. Means, disk-based cache buffer information storing information comprising a model number of the magnetic disk device and cache segment size, and searching for the disk-based cache buffer information based on the model number of the magnetic disk device obtained by the connected disk recognizing means. A disk cache buffer securing processor for securing a memory required for the disk cache buffer from the determined cache segment size.