JPH11249937A - Computer system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a computer system which improves the performance of the file read/write speed for an auxiliary storage device. SOLUTION: This computer system is provided with a file system 14, which issues a read instruction or a write instruction based on a file operation instruction from a user program 13 as a file operation function, and a device driver 16 which issues a control instruction to a control circuit 17 which performs file read/write control for an auxiliary storage device 18, based on the instruction issued from the file system 14. The device driver 16 controls the control circuit 17 so that direct data transfer may be performed between the auxiliary storage device 18 and user data 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer system capable of reading and writing files to and from an auxiliary storage device at high speed.

[0002]

2. Description of the Related Art In a computer system, an operating system (hereinafter abbreviated as "OS") is used in order to facilitate a user program to operate various devices.
Is provided. As one function of the OS, a function of reading and writing data from and to an auxiliary storage device, that is, a file operation function is provided. FIG. 5 is a conventional example showing the concept of file operation in a computer system. As shown in the figure, in order to realize a file operation, the functions are provided by a hierarchical structure of a file system 24, an intermediate buffer 25, and a device driver 26. The reason for providing the functions in a hierarchical structure is to enhance the versatility of the functions. The file system 24, the intermediate buffer 25, and the device driver 26 operate in the kernel mode 22 having a high access right in order to prevent unauthorized access by the user program 23 or the like. On the other hand, the file system 24
Storage device 2 using the interface provided by
User program 23 that performs file operations on file 8
Operates in the user mode 21 having a low access right. In FIG. 5, the left side of the dashed line 20 shows the flow of the file operation command, and the right side shows the flow of the file data. The operation in the file operation will be described with reference to FIG.

When reading a file stored in the auxiliary storage device 28, first, a command to write a file from the user program 23 is transmitted to the file system 24. The file system 24 analyzes the command, obtains the location of the file in the auxiliary storage device 28, and transmits the read command of the location to the intermediate buffer 25. The intermediate buffer 25 sequentially issues the received read command to the device driver 26 so as to read the read command in units of the data area size of the intermediate buffer 25. The device driver controls the control circuit 27 to transfer data from the auxiliary storage device 28 to the data area of the intermediate buffer 25 as shown by the path 30. The intermediate buffer 25 transfers the data transferred as indicated by the path 31 to the user data 29 in the user mode 21. When the processing of all divided read commands is completed by the intermediate buffer 25, control returns to the user program.

On the other hand, when writing a file to the auxiliary storage device 28, first, a write command to the file is transmitted from the user program 23 to the file system 24. The file system 24 calculates a position in the auxiliary storage device 28 where the file is to be recorded, and transmits a write command to the position to the intermediate buffer 25. The intermediate buffer 25 sequentially issues instructions to the device driver 26 so as to write the received write instruction in units of the data area size of the intermediate buffer 25. At the same time, the intermediate buffer 25 sequentially transfers the user data 29 to the intermediate buffer with the data area size as shown in the path 31. On the other hand, the device driver 26
The control circuit 27 controls the transfer of data from the data area of the intermediate buffer 25 to the auxiliary storage device 28 as shown by the path 30. As described above, the file operation is performed via the intermediate buffer 25.

[0005]

Here, the computer system is controlled by a control program on the OS. The OS operates in two modes: a user mode and a kernel mode. As described above, the user program 23 operates in the user mode 21 and the file system 2 operates in the user mode.
The programs 4 and below operate in the kernel mode 22. The data area in the user mode and the data area in the kernel mode are managed separately by the OS.
When transferring data between the two, the intermediate buffer 25
Is to be done via This intermediate buffer 2
Reference numeral 5 generally has a plurality of buffer areas each having a data area size of about 64 kilobytes. When transferring data having a size larger than this size, the transfer command is executed in a plurality of times. On the other hand, in the auxiliary storage device 28 used in the computer system, better performance is obtained when reading or writing is performed in the largest possible size unit. However, since the intermediate buffer 25 issues a read or write command in the data area size of the intermediate buffer 25, this portion is a bottleneck in data transfer performance between the auxiliary storage device 28 and the user data 29. That is, the transfer between the auxiliary storage device and the intermediate buffer and the transfer between the intermediate buffer and the user data are performed twice, so that the efficiency is reduced. In addition, the former transfer is applied by hardware transfer using a control circuit of the auxiliary storage device, whereas the latter transfer is generally realized by software in many cases.
Performance degradation due to this point is also large.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide a computer system that improves the performance of a file reading speed and a writing speed with respect to an auxiliary storage device.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, as a file operation function, at least a read instruction or a write instruction based on a file operation instruction from a user program is provided. A computer system for executing a file system that issues instructions, and a device driver that issues control instructions to a control circuit that performs read / write control of a file in an auxiliary storage device based on the instructions issued by the file system. The computer system is characterized in that the driver controls the control circuit so as to directly transfer data between the auxiliary storage device and designated user data. According to a second aspect of the present invention, in the computer system according to the first aspect, the file system directly issues a read command or a write command to the device driver.

[0008] Further, the invention described in claim 3 is based on claim 2.
The computer system according to claim 1, wherein the file system determines whether the user-data is directly accessible from the control circuit, and directly issues a read command or a write command to the device driver when the user system is directly accessible. Features. According to a fourth aspect of the present invention, in the computer system according to the second aspect, a read command or a read command to the device driver is issued only when the file system issues a file data read command or a file data write command. It is characterized in that a write instruction is issued directly.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a computer system according to an embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 1 is a diagram showing a configuration example of a computer system of the present invention. As shown in the figure, the computer system 1 includes a CPU (Central Processing Unit) 2 for executing a program and the like, a memory 3 on which a program is loaded and a data area is secured, and A bus 5 for connection is provided. Here, the computer system 1 refers to a system that performs file operations on an auxiliary storage device such as a so-called personal computer, workstation, or word processor. Memory 3 is RAM (Random Access)
Memory). When the computer system 1 starts up, the file system 14, the device driver 16, and the intermediate buffer 15 operating in the kernel mode are stored in the memory 3 by loading a file provided as a program, or an area is secured. Is done. Then, at the start of the execution of the user program, the user program is loaded onto the memory 3, and the user data area 19 'is secured if necessary. The intermediate buffer 15 here includes a program for exchanging data via the buffer area in accordance with an instruction from the file system 14, in addition to a so-called buffer area.

On the other hand, a control circuit 17 for controlling an auxiliary storage device 18 in accordance with a command from a device driver 16 is connected to the bus 5 of the computer system 1 via a predetermined interface 4. The control circuit 17 is provided as a SCIS mode or a PCI card as a specific example. The auxiliary storage device 18 is composed of a non-volatile recording medium such as a bird disk, a floppy disk, a magneto-optical disk, a compact disk, a flash memory, and a drive mechanism for them. Note that the auxiliary storage device 18 here may be provided outside the computer system 1 or may be built in the computer system 1. The recording medium constituting the auxiliary storage device 18 is managed with a predetermined recording block size generally called a sector. The area recorded on the recording medium is roughly divided into a data area 42 for recording file data and a FAT (File Allocation Table) area 41 for managing file data recorded in the data area 42. You. In the FAT area 41, attribute information such as a file name to be recorded, file arrangement information, information on a file directory entry, and the like are recorded. Further, by referring to the FAT area, it is possible to know which part of the data area is an unused area.
The FAT here is a general term for table information for managing file data. Thus, for example, U
The i-node in NIX is also included in this. In addition,
A display device 3 such as a CRT (Cathode Ray Tube) and an input device 7 such as a mouse and a keyboard are connected to the computer system 1 via an interface (not shown).

Hereinafter, the operation of the file operation of the computer system 1 for the auxiliary storage device 18 will be described with reference to the drawings. FIG. 1 is a diagram showing an operation concept of a file operation in the computer system 1 of the present invention. FIG.
, The file system 14, the intermediate buffer 15, and the device driver 16 operate in the kernel mode 12 having high access authority, and the user program 13 operates in the user mode 11 having relatively low access authority.
In FIG. 1, the left side of the dashed line 10 shows the flow of the file operation command, and the right side shows the flow of the file data. FIG. 3 shows the computer system 1
6 is a flowchart showing the operation of a file operation in FIG. Hereinafter, the operation of the file operation will be sequentially described with reference to FIG. First, when the user program 13 issues a file operation command, the file system 14 accepts the file operation command (step S1). Here, the “file operation command” refers to a file read command or a file write command to the auxiliary storage device 18. In addition,
The file operation command also includes information necessary for file operation, such as the start address of the user data 19 in the memory 3 and the name of the file to be operated.

Next, the file system 1 analyzes the file operation command and refers to the FAT to determine in which position of the auxiliary storage device 18 the file is recorded, or in which position. Is obtained (step S2). Here, the FAT is referred to when referring to the FAT area 41 in the auxiliary storage device 18 or when reading a part or all of the data of the FAT area 41 into the memory 3 in advance and referring to it. is there. Next, the file system 14 determines from the kernel mode 12 whether the user data 19 from which the file is to be read or written is visible, that is, whether or not the control circuit 17 can directly access the user data 19 (step S3). With this determination, it is possible to cope with the case where the user data 19 is directly accessible from the control circuit 17 and the case where it is not possible.

If the access is not possible, the file system 14 sequentially issues a data read command or a write command from the auxiliary storage device 18 to the intermediate buffer 15 based on the arrangement information obtained in step S2, as in the conventional system. Issue (step S4). The intermediate buffer 15 accesses the auxiliary storage device 18 via the device driver 16 and the control circuit 17 in units of the data area size of the intermediate buffer 15 and transfers data between the user data 19 and the auxiliary storage device 18 to the data area of the intermediate buffer 15. (Step S5).

On the other hand, if the access is possible, the file system 14 sends a data read command or a write command from the auxiliary storage device 18 directly to the device driver 16 based on the arrangement information obtained in step S2. Issue (step S6). At this time, the instruction is issued so that the number of data transfers is reduced as much as possible. Thereby, the number of times of data transfer is reduced, and the transfer efficiency is increased. Based on an instruction from the file system 14, the device driver 16
7 is controlled so as to directly execute data transfer between the auxiliary storage device 18 and the user data 19 as shown by the path 20 in FIG. 1 (step S7). Control circuit 17
In this method, high transfer efficiency can be obtained because data is transferred by hardware. Note that as a data transfer method performed here, DMA (Direct Memory Access) transfer or the like is used.

When the file operation based on the command issued by the user program 13 is completed, the control is returned to the user program 13. Generally, when reading and writing the data portion of the file, the data can be transferred without passing through the intermediate buffer 15, and the processes in steps S6 and S7 are performed. The “file data” here refers to data other than FAT information, and refers to data recorded in the data area 42 in FIG. On the other hand, it is preferable that FAT information, for example, file arrangement information, file attributes, directory entry information, and the like be transferred via the intermediate buffer 15 for stable operation. Since the amount of FAT information is small, even if the FAT information is transferred via the intermediate buffer 15, it does not lead to a decrease in the overall transfer efficiency. Therefore, the file system 14 may determine in step S3 whether to proceed to step S6 or step S4 depending on whether to read or write file data or to read or write other data.

Since the above-described file operation is performed in the computer system 1, data transfer without the intermediate buffer 15 is possible. Thus, the transfer between the control circuit 17 and the user data 19 is performed by the control circuit 1
7 using the hardware transfer function
High-speed data transfer can be realized without the intervention of U2 processing. Further, in hardware transfer, data can be read and written in a single operation, so that high-speed data transfer can be realized. Further, even if the data amount of the file is large, the read or write command issued from the file system 14 is not divided into read or write commands in units of the data area size of the intermediate buffer 15, thereby reducing the number of transfers. Can be achieved.
Further, the process of software transfer of data by the intermediate buffer 15 is also eliminated. Therefore, the performance of the reading speed and the writing speed of the file with respect to the auxiliary storage device 18 can be improved. Further, when the user data 19 is accessible from the kernel mode, the data transfer is executed directly using the path 20 shown in FIG. 1, so that the frequency of the data transfer can be reduced.

Next, a file operation in the computer system 1 when UNIX is used as the OS will be described as a specific example. FIG. 4 is a diagram showing an operation concept of file operation when UNIX is provided as the OS. Note that the device configuration of the computer system and the operation flow in file operation are basically the same as those in FIGS. FIG.
, Reference numeral 32 denotes a user program, and reference numeral 33 denotes a user program.
Is a virtual file system, 34 is UNIX
Reference numeral 35 denotes a buffer cache (intermediate buffer), and reference numeral 36 denotes a software stack of a device driver. The user program 32 operates in a user mode, and the virtual file system 33, UNIX file system 34, buffer cache 35, and device driver 36 operate in a kernel mode. Reference numeral 37 denotes a control circuit of an auxiliary storage device such as a hard disk, and reference numeral 38 denotes an auxiliary storage device. An example in which one control circuit 37 controls a plurality of auxiliary storage devices 38 is shown. Reference numeral 39 denotes user data on the user program. Reference numeral 40 denotes an auxiliary storage device 38 and user data 39.
Reference numeral 41 denotes an instruction path other than reading / writing of file data, and reference numeral 42 denotes an instruction path in reading / writing of file data.

The operation of file operation when UNIX is provided as the OS is as follows. Here, the user data 39 is read only when reading / writing file data.
And the auxiliary storage device 38 is controlled so that data transfer is performed directly. When the user program 32 reads and writes file data, read and write commands are transmitted as in the command path 42. That is, when the user program 32 issues a command to read or write file data using a read function (read function of file data), a write function (related to writing of file data), or the like, a lower-level function sends the command through the virtual file system 33. The command is transmitted to the UNX file system 34 (step S
1).

When the UNIX file system 34 determines that the instruction is a file operation instruction, the UNIX file system 34 directly executes a special processing function (direct access function) provided in the device driver 36 without going through the mechanism of the buffer cache 36. Call to read file data,
Alternatively, a write command is transmitted (step S6). When high-speed data transfer using the hardware of the control circuit 37 is performed, it corresponds to m1ock (memory lock) so that the memory space in the user mode can be seen from the kernel mode somewhere in this stage. It is necessary to complete the process of mapping the user data 39 to the physical memory space using the function (mapping process). This is to suppress processing performance degradation due to page faults in the virtual storage. And finally, in the case of a read command, the direct access function in the device driver 36 reads the data from the auxiliary storage device 38 to the user data 39.
In the case of writing, an instruction is issued to the control circuit 37 so that the data is directly transferred from the user data 39 to the auxiliary storage device 38. Then, as shown in the path 40, the transfer of the file data is performed without passing through the buffer cache (step S7).

Next, when information other than file data, for example, directory entry information and file arrangement information is read (step S3), reading and writing are performed using the same ordinary path 41 as the conventional method. That is, the read command and the write command are transmitted to the buffer cache 3
5 (step S4), the buffer cache 3
5 performs a process of temporarily storing data in a memory area in the buffer cache 35 and then transferring the data (step S5). Since this memory area is always allocated to the physical memory space, there is no need to perform a map process. Since the transfer between the buffer memory area and the user memory 39 is performed by software, the user memory 3 is automatically transferred by the page fault function of the UNlX.
Nine map processes are performed. In UNIX, since the memory space in the user mode can or cannot be directly accessed from the kernel mode, the determination shown in step S3 in FIG. 3 is necessary. As described above, in the computer system 1, the file operation is performed when UNIX is provided as the OS.

As described above, data is directly transferred between the user data and the auxiliary storage device. Therefore, the data does not pass through the intermediate buffer, and the reading speed and the writing speed for the auxiliary storage device can be improved. Further, since the file system issues a read / write command directly to the device driver without passing through the intermediate buffer, even a read / write command having a large file size can be transmitted to the device driver as one command. As a result, data transfer between the user data and the auxiliary storage device can be realized at one time. The effect is great because file data is generally recorded in a continuous area in the auxiliary storage device. Further, since the transfer efficiency greatly depends on the transfer speed of file data having a large data amount, the transfer efficiency can be increased by performing direct transfer between the user data and the auxiliary storage device at least in the transfer of the file data. it can. In addition, since the reading speed and writing speed for the auxiliary storage device can be improved only by adding new functions to the file system and device driver, there is no need to change the conventional file recording format, circuit configuration of the control circuit, etc. High-speed file input and output.
An OS program including the functions of the file system 14 and the device driver 16 shown in FIG. 1 is recorded on a computer-readable recording medium, and the program recorded on this recording medium is read by a computer system to perform file operations. You may do so. As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes a functional change within a scope not departing from the gist of the present invention.

[0022]

As described above, according to the computer system of the present invention, by reading or writing file data without using an intermediate buffer, data transfer between the auxiliary storage device and user data can be performed directly. It is possible to do. Therefore, the performance of the reading speed and writing speed of the file with respect to the auxiliary storage device is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an operation concept of a file operation in a computer system of the present invention.

FIG. 2 is a diagram showing a configuration of a computer system of the present invention.

FIG. 3 is a flowchart showing an operation of a file operation.

FIG. 4 is a diagram showing an operation concept of a file operation when UNIX is provided as an operating system.

FIG. 5 is a diagram showing an operation concept of a conventional file operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Computer system 2 CPU 3 Memory 5 Bus 6 Display device 7 Input device 11 User mode 12 Kernel mode 13 User program 14 File system 15 Intermediate buffer 16 Device driver 17 Control circuit 18 Auxiliary storage device 19 User data 19 'User data area 20 Data Transfer path 41 FAT area 42 Data area

Claims (4)

[Claims] 1. The file operation function includes at least:
A file system that issues a read command or a write command based on a file operation command from a user program, and a device that issues a control command to a control circuit that performs file read / write control on an auxiliary storage device based on the command issued by the file system A computer system for executing a driver, wherein the device driver controls the control circuit so as to directly transfer data between the auxiliary storage device and designated user data. 2. The computer system according to claim 1, wherein the file system issues a read command or a write command directly to the device driver. 3. The file system according to claim 1, wherein the control circuit determines whether the user data is directly accessible or not, and when the user data is directly accessible, directly issues a read command or a write command to the device driver. 3. The computer system according to claim 2, wherein: 4. The file system according to claim 2, wherein the file system issues a read command or a write command directly to the device driver only when issuing a file data read command or a file data write command. Computer system.