JP2787107B2 - Buffer control system and device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to information processing by a computer, and more particularly to a buffer control method and apparatus suitable for a real-time system.

[Conventional technology]

In the prior art, a memory (buffer area) called a buffer is prepared so that every time a file stored in the auxiliary storage device is operated, input / output of target data between the auxiliary storage device and the main storage device does not occur. It is known to (Reference, NTT Telecommunications Laboratories, S. Kido, "Effects of buffer control on large-scale DB systems," Information Processing Society of Japan
35th (late 1987) National Congress, 427-428)
In that case, a program that performs file operations, such as a file management system and a database management system, performs the following processing. FIG. 3 is a flowchart showing processing for file operations in the file management system and the database management system, and the processing will be described with reference to the flowchart.

(A) In accordance with a file operation instruction from a user program, control information for each surface of a buffer memory is searched to determine whether target data exists in a buffer.

(B) If the target data exists in the buffer,
Transfer data between the buffer and the program.

(C) When the target data does not exist in the buffer, the data is read from the auxiliary storage device onto the buffer,
Set the control information for that buffer. Thereafter, data transfer is performed between the buffer and the program.

(D) When data is updated in the buffer, the update result is transferred to the auxiliary storage device.

As described above, in the buffer management method in which the buffer is arranged in the memory that can be referred to by a plurality of tasks and the buffer is shared by the plurality of tasks, the memory use efficiency and the hit ratio (the probability that the target data exists in the buffer) are improved. In addition, it is known that the task throughput is improved.

However, in the above-described buffer management method in which a plurality of tasks share a buffer, a conflict management method for preventing erroneous data access or data destruction by simultaneously sharing a buffer among a plurality of tasks is required.

Conventionally, since contention management is performed on the entire buffer area, the following method has been adopted.

In the contention management in the buffer management system in which a buffer is shared by a plurality of tasks, the following processing is performed as shown in the flowchart of FIG.

(A) When searching in the buffer, always determine the contents of the availability control information for the entire buffer, and if not set, set the availability control information for the entire buffer.
Exclusively occupy the buffer.

If the contents of the availability control information for the entire area of the buffer have already been set, the process waits until the occupancy of the buffer is released.

(B) Whether or not the target data exists in the buffer is determined by searching the control information for each surface of the buffer.
If the target data exists on the buffer,
Release the setting of the usability control information for the entire buffer area and release the occupancy of the buffer.

(C) If the target data does not exist in the buffer, the control information for each surface of the buffer is searched for an empty buffer. Thereafter, data is read from the auxiliary storage device onto the empty buffer, and control information of the buffer is set.

(D) If the data has been updated in the buffer detected as an empty buffer, target data is read from the auxiliary storage device after transferring the update result to the auxiliary storage device.

(E) After the data has been transferred from the auxiliary storage device to the buffer, control information of the buffer is set. afterwards,
Release the setting of the usability control information for the entire buffer area and release the occupancy of the buffer.

As described above, data search in the buffer and transfer of data from the auxiliary storage device to the buffer cannot be performed at the same time.

[Problems to be solved by the invention]

The above prior art has good memory use efficiency, buffer hit rate, etc., but has the following problems.

That is, the search of data in the buffer and the transfer of data from the auxiliary storage device to the buffer cannot be performed in parallel,
When the sharing degree of the task with respect to the buffer is high, the throughput of the task decreases.

It is an object of the present invention to improve the task throughput by being able to search for data in a buffer and transfer data from an auxiliary storage device to the buffer in parallel.

[Means for solving the problem]

In order to achieve the above object, the present invention has a buffer area having a plurality of divided surfaces capable of high-speed access between a processing device and an auxiliary storage device. In the buffer control method performed through the buffer area, access control information is set for each division plane in the buffer area, and data transfer processing from the auxiliary storage device to the division plane is performed according to the availability control information. Based on this, the data transfer process and the data search process for another divided plane in the buffer area are performed in parallel.

Further, the above object is to provide availability control information for the entire buffer area capable of high-speed access, to set availability control information when operating the buffer area, to cancel the setting at the end of the operation, and to enable high-speed access. The available buffer area is divided into a plurality of parts, the usability control information is provided for each of the divided buffer areas, the usability control information is set before data is transferred from the auxiliary storage device to the buffer area, and when the data transfer is completed. ,
This can be achieved by canceling the setting.

Further, such a buffer control method can be applied to a database management system.

[Action]

According to the above configuration, the division plane to which data is transferred is specified by the usability control information for each division plane, and other division planes in the buffer area can be released, so that data transfer processing from the auxiliary storage device can be performed. The data search processing in the buffer area can be performed in parallel. Therefore, the throughput of data access from the processing device is improved.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the principle of the present embodiment.
When referring to, updating, adding, or deleting data in the auxiliary storage device 4 from a task in the server, the task is performed through a buffer area (buffer memory) 6 that allows high-speed access. When a plurality of tasks use the buffer area 6 at the same time, the task using the buffer area 6 first determines the contents of the availability control information 8 on the entire buffer area.

When the usability control information 8 for the entire buffer area is not set, the usability control information 8 for the entire buffer area is set,
Exclusively occupies the entire buffer area 6.

If the usability control information 8 for the entire buffer area has already been set, the process waits until the setting is canceled.

The task that initially occupies the buffer area 6 determines the divided buffer area 10 in which the target data is present as follows.

The divided buffer area 10 has the following control information for each surface.

(1) Usability control information 12 (2) State control information 14 (a file identifier indicating which file the data existing in the divided buffer area 10 belongs to, a block number in the file, and a data update) A flag indicating whether or not a task has occurred and a flag indicating whether there is a task using the buffer area.) When searching the buffer 6, how many blocks in the file contain the target data Is calculated, and the state control information 14 in the divided buffer area 10 is sequentially searched.

At this time, the buffer area 10 in which the availability control information 12 of the divided buffer area 10 is set is not a search target because the used task is already reading data from the auxiliary storage device 4. For the buffer area 10 in which the usability control information 12 of the divided buffer area 10 is not set, it is sequentially searched for whether the file identifier as the state control information 14 and the block number in the file match. The buffer area 10 in which the file identifier and the block number in the file match is the buffer area 10 in which the target data exists.

If the target data does not exist in the divided buffer area 10, the free buffer area 10
Search for. The empty buffer area is determined as follows.

The buffer area 10 in which the file identifier which is the state control information of the divided buffer area 10 is not set or the file identifier is set but the flag indicating whether there is a task using the buffer area is not set. The buffer area 10 of FIG.

If data update has occurred on the buffer area 10 detected as an empty buffer area, that is, if a flag indicating whether data update as control information of the buffer area has occurred has been set, The data in the divided buffer area is transferred to the auxiliary storage device 4. After the data transfer to the auxiliary storage device 4 is completed, the usability control information 12 of the divided buffer area 10 is set, the occupancy of the entire buffer area 6 is released, and the divided buffer area 6 is released from the auxiliary storage apparatus 4. Transfer data to area 10.

By releasing the occupation of the entire buffer area 6, the entire buffer area 6 is released.
The other task waiting for the release of the buffer exclusively occupies the entire buffer area 6.

The entire buffer area 6 is exclusively occupied, and it is searched whether the target data exists in the divided buffer area 10.

However, the divided buffer area 10 that is determined as the operation target by the task that first occupies the entire buffer area 6 is not the search target because the availability control information 12 is set. While the availability control information 12 of the divided buffer area 10 is set, the divided buffer area 10 is not simultaneously operated by a plurality of tasks.

Accordingly, in the present embodiment, in the control method in the case where a buffer area capable of high-speed access is shared by a plurality of tasks,
The data retrieval in the buffer area and the data transfer from the auxiliary storage device to the buffer area can be executed in parallel, and the throughput of data access from the processing device can be improved. still,
In the figure, reference numeral 16 denotes a main memory device.

FIG. 2 is a principle diagram of a conventional buffer control method,
FIG. 1 is a principle diagram of the buffer control method according to the present invention, in which usability control information is added to each surface of the buffer in FIG. FIGS. 5 and 6 are flowcharts showing a shared buffer control system in which a buffer is arranged on a memory that can be referred to by a plurality of tasks and can be operated simultaneously by a plurality of tasks. Next, a control method will be described with reference to FIG. 7 in which a buffer is arranged on a memory that can be referred to by a plurality of tasks, and a shared buffer can be simultaneously operated by a plurality of tasks.

FIG. 7 shows availability control information 8 of the entire shared buffer,
Through the shared buffer 6 including the state control information 14 of each surface of the shared buffer and the availability control information 12 of each surface of the shared buffer,
A task 20 for accessing the auxiliary storage file 18, a task 24 for accessing the auxiliary storage file 22 via the shared buffer 6, and the auxiliary storage file 18, the auxiliary storage file 22
Represents the auxiliary storage device 4 which secures the information.

The task 20 performs a process of reading data A and B from the auxiliary storage file 18.

The task 24 performs a process of reading the data a and b from the auxiliary storage file 22.

Now, it is assumed that the two tasks have the same priority level of the processing unit allocation, and that no input / output occurs to the auxiliary storage device except for the data transfer between the auxiliary storage file and the shared buffer. In the case of starting operation almost simultaneously in the order of 24, task 20, task
This embodiment will be specifically described with reference to a time chart of FIG. 24 and a state transition diagram of the shared buffer.

In FIG. 8, reference numeral 26 denotes a time chart of the tasks 20 and 24. Reference numeral 28 denotes a state transition diagram of the shared buffer 6 due to the execution of the task 20.
Reference numeral 30 denotes a state transition diagram of the shared buffer 6 by the task 24.

When the execution of the task 20 is started, the availability control information of the entire shared buffer is set to occupy the entire shared buffer 32 (time t = 1), and it is determined whether or not the data A to be read exists in the shared buffer. Search for.

Whether or not the data to be read exists in the shared buffer is determined as follows.

 The following control information is provided for each surface of the shared buffer.

(1) action enable / disable control information; (2) state control information (a file identifier indicating which file is the data on the shared buffer, a block number in the file, and whether or not data has been updated on the shared buffer) A flag indicating whether there is a task using the buffer and whether there is a task using the buffer.) When searching in the shared buffer, the file identifier of the control information for each surface of the shared buffer matches the block number in the file. Are sequentially searched to see if they are The matched buffer is the target buffer. At this time, the buffer in which the usability control information is set is not searched.

A file identifier which is control information of each side of the shared buffer,
And if all the block numbers in the file do not match,
Detect a free buffer. An empty buffer is detected as follows.

A buffer in which the file identifier as the control information of the shared buffer is not set, or a buffer in which the flag indicating the presence / absence of the task which is the control information of the shared buffer is not set is set as an empty buffer.

The task 20 searches whether or not the data A exists on the shared buffer by the above search method, but the data A is not on the shared buffer. Therefore, the empty buffer block 32
a is detected, its availability control information is set, and the empty buffer block 32a is occupied. Then shared buffer 32
The setting of the entire usability control information is released, and (time t =
2) Read data A from the auxiliary storage file 18 into the occupied block 32a of the shared buffer 32 (time t = 2-5).

The task 24 starts executing at the same time as the task 20 starts reading data from the auxiliary file, sets the availability control information of the entire shared buffer, occupies the entire shared buffer 34 (time t = 3), and reads the data to be read. It is searched whether or not a exists in the shared buffer. At this time, the buffer 32a searched as a free buffer by the task 20 is not detected by the task 24 as a search target buffer because the availability control information is set.

Since the data a is not on the shared buffer, the availability control information of the empty buffer block 34a is set and the empty buffer block 34a is occupied. Thereafter, the setting of the availability control information of the entire shared buffer 34 is canceled (time t = 4), and the occupied block 34 of the shared buffer 34 is deleted from the auxiliary storage file 22.
Read data a into a. (Time t = 5 to 8) After the reading of the data A is completed, the task 20 releases the setting of the availability control information of the shared buffer block 32a and enables the task 24 to access the shared buffer block 32a.

After reading the data a, the task 24 releases the setting of the availability control information of the shared buffer block 34a, and enables the task 20 to access the shared buffer block 34a.

Task 20 performs the same processing on data B as on data A. The task 24 performs the same processing on the data b as on the data a.

According to the present embodiment, while task 20 is transferring data from auxiliary storage file 18 to shared buffer 6, task 24
Since the shared buffer 6 occupies the shared buffer 6 and can execute processing, the throughput is improved as compared with the time chart of FIG.

Next, a case will be described in which the task 20 for accessing the auxiliary storage file 18 via the shared buffer 6 and the task 24 for accessing the auxiliary storage file 22 via the shared buffer 6 have different priority levels of processor assignment.

If task 20 has a higher processing unit assignment priority level than task 24, even if tasks 20 and 24 start operations almost simultaneously, task 20 is assigned a processing unit only if task 20 has a shared buffer. Since the input and output are occurring between the CPU and the auxiliary storage device, the operations of the tasks 20 and 24 are the same as those in FIG. Therefore,
There is an effect that the throughput is improved as compared with the time chart in FIG.

Next, a case where the operation of the task 20 is started at almost the same time in the order of the task 20 and the task 24 when the priority level of the processing device assignment is lower than that of the task 24 will be described. No.
In FIG. 10, reference numeral 36 denotes a time chart of the tasks 20 and 24. Reference numeral 38 denotes a state transition diagram of the shared buffer 6 due to the execution of the task 20. Reference numeral 40 denotes a state transition diagram of the shared buffer 6 due to the execution of the task 24. When the execution of the task 20 is started, the entirety of the shared buffer 42 is occupied (time t = 1), and it is searched whether the data A to be read exists in the shared buffer. Data A is not in the shared buffer, so free buffer
The usability control information of the shared buffer 44a is set, and the setting of the usability control information of the entire shared buffer 44 is canceled (time t = 2).
When the occupation of the entire shared buffer is released, the task 24 starts operating, sets the availability control information of the entire shared buffer, and occupies the entire shared buffer 46 (time t =
3) Search whether the data a to be read exists in the shared buffer. At this time, the buffer 44a searched by the task 20 as an empty buffer is not a buffer to be searched from the task 24 because the availability control information is set. Since the data a is not in the shared buffer, the availability control information of the empty buffer block 46a is set, the empty buffer block 46a is occupied, and the availability control information of the entire shared buffer 46 is released (time t = 4). Auxiliary storage file
Data a is read from 22 to the occupied block 46a of the shared buffer 46. (Time t = 5-7).

Task 20 operates while task 24 is transferring data between auxiliary storage file 22 and the shared buffer, and issues a data transfer instruction to the auxiliary storage device, but since task 24 has already used the auxiliary storage device, , Waiting for the auxiliary storage device to become usable (time t = 5 to 7). At the same time when the data transfer of task 24 is completed, task 20 reads data A. (Time t = 10).

Task 20 performs the same processing on data B as data A, and task 24 performs the same processing on data a.

According to the present embodiment, there is an effect that the throughput is improved as compared with the time chart in FIG.

Next, database management that secures a plurality of frequently accessed files in different auxiliary storage devices in the database and improves the task throughput by using the same shared buffer when accessing each file. 1 shows an embodiment of a system.

 FIG. 12 shows the configuration of the database.

Task 50 accesses a file 54 in auxiliary storage 52 via a database management system, and task 56 accesses a file 60 in auxiliary storage 58. FIG. 13 shows a time chart 62 of the task 50 and the task 56, and a time chart 64 of the task 50 and the task 56 when the files to be accessed in the task 50 and the task 56 are secured in the same auxiliary storage device.

As task 50 begins reading data from the file in auxiliary storage 52, task 56 operates to read data from the file in auxiliary storage 58. (Time t =
4) At this time, the task 50 and the task 56 access different auxiliary storage devices.
The data transfer from the auxiliary storage device 58 to the shared buffer can be executed without waiting for the end of the data transfer from the shared storage 52 to the shared buffer.

As a result, the task throughput is improved as compared with the time chart 64 when a plurality of files are secured in the same auxiliary storage device.

〔The invention's effect〕

According to the present invention, retrieval of data in a buffer area capable of high-speed access and transfer of data from the auxiliary storage device to the buffer area can be performed in parallel, thereby improving the throughput of data access from the processing device. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the basic principle of one embodiment of the present invention,
FIG. 2 is an explanatory view showing the principle of the prior art, FIG. 3 is a flowchart of an example of a file operation program focusing on buffer control processing, FIG. 4 is a flowchart showing a shared buffer control method according to the prior art, and FIGS. FIG. 6 is a flowchart showing a shared buffer control method according to the present embodiment;
FIG. 7 is a diagram showing the basic concept of the shared buffer, FIGS. 8 and 10 are time charts showing an embodiment of the present invention and a state transition diagram of the shared buffer, and FIGS. 9 and 11 are based on the conventional method. Time chart and state transition diagram of shared buffer, twelfth
FIG. 13 and FIG. 13 are explanatory diagrams showing a configuration and an embodiment in which the present invention is applied to a database management system. 2 ... Processing device, 4 ... Auxiliary memory device, 6 ... Buffer memory (buffer area), 8 ... Buffer memory availability control information, 12 ... Usability control information for each surface of the buffer memory.

Continued on the front page (72) Inventor Kohei Seki 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture Within Hitachi Process Computer Engineering Co., Ltd. (72) Inventor Takashi Owaki 5-2-1 Omika-cho, Hitachi City, Ibaraki Prefecture No. Hitachi, Ltd. Omika Plant (72) Inventor Toshimasa Matsubara 5-2-1 Omikacho, Hitachi City, Ibaraki Prefecture Within Hitachi Process Computer Engineering Co., Ltd. (56) References JP-A-63-83821 (JP, A) JP-A-60-175158 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G06F 3/06 G06F 12/08

Claims (7)

(57) [Claims] A buffer area having a plurality of divided surfaces capable of high-speed access is provided between a processing device and an auxiliary storage device, and when the processing device accesses the auxiliary storage device, the buffer area is provided. In the buffer control method performed via, setting the usability control information for each divided surface in the buffer area,
The data transfer processing from the auxiliary storage device to the division plane is performed based on the availability control information, so that the data transfer processing and the data search processing of another division plane in the buffer area are performed in parallel. Buffer control method. And a buffer area having a plurality of divided surfaces capable of high-speed access between the processing device and the auxiliary storage device. Access from the processing device to the auxiliary storage device includes a buffer area. In the buffer control method performed through the buffer area, use availability control information is provided for each divided plane in the buffer area, and when starting data transfer processing from the auxiliary storage device to the divided plane, the use information of the divided plane is set, and By releasing the setting of the use information at the end of the transfer processing, the data transfer processing from the auxiliary storage device to the division plane and the data search processing of other division planes in the buffer area can be executed in parallel. A buffer control method characterized in that: 3. A buffer area having a plurality of divided surfaces capable of high-speed access is provided between a processing device and an auxiliary storage device, and when the processing device accesses the auxiliary storage device, the buffer area is provided. In the buffer control method performed through the control unit, the usability control information for each divided plane in the buffer area is provided together with the usability control information for the entire buffer area, and the usability control information of the buffer area is set when the buffer area is operated. When the operation is completed, the setting is released, and when data is transferred to the division plane in the buffer area, the usability control information for each division plane is set, and when the data transfer is completed, the setting is released. A buffer control method wherein a transfer process and a data search process in the buffer area are performed in parallel. 4. A buffer area having a plurality of divided surfaces capable of high-speed access between a processing device and an auxiliary storage device, and access from the processing device to the auxiliary storage device is performed by using the buffer area. In the buffer control device performed through, a usability control information device for each division plane in the buffer area is provided, and at the start of data transfer processing from the auxiliary storage device to the division plane, the usability control information device includes By setting the usage information and releasing the setting of the usage information at the end of the data transfer processing, the data transfer processing from the auxiliary storage device to the division plane and the data search processing of the other division plane in the buffer area Characterized by being able to execute in parallel. 5. A buffer area having a plurality of divided surfaces capable of high-speed access between a processing device and an auxiliary storage device, wherein an access from the processing device to the auxiliary storage device includes the buffer area. A buffer control device for controlling the use of the buffer area, wherein a control information apparatus is provided for each divided plane in the buffer area together with the control information for the entire buffer area, and the control information of the buffer area is set when the buffer area is operated. When the operation is completed, the setting is released, and when data is transferred to the division plane in the buffer area, the usability control information for each division plane is set, and the setting is released at the end of data transfer. A buffer control device for performing a data transfer process and a data search process in the buffer area in parallel. 6. A buffer area having a plurality of divided surfaces capable of high-speed access between a processing device and an auxiliary storage device, wherein the access from the processing device to the auxiliary storage device includes the buffer area. In a database management system using a buffer control method performed through the database, use availability control information for each division plane in the buffer area is provided, and when the data transfer process from the auxiliary storage device to the division plane is started, the usage information of the division plane is used. And setting of the use information is canceled at the end of the data transfer processing, so that the data transfer processing from the auxiliary storage device to the division plane and the data search processing of other division planes in the buffer area can be performed. A database management system characterized by using a buffer control method that can be executed in parallel. 7. A buffer area having a plurality of divided surfaces capable of high-speed access between a processing device and an auxiliary storage device, and an access from the processing device to the auxiliary storage device includes the buffer area. In a database management system using a buffer control method that is performed via a database, use enable / disable control information for each division plane in the buffer area is provided together with enable / disable control information for the entire buffer area, and use of the buffer area is performed when the buffer area is operated. Set the availability control information and release the setting at the end of the operation, and when transferring data to the division plane in the buffer area, set the usability control information for each division plane and change the setting at the end of data transfer. A database management system characterized by using a buffer control method for performing the data transfer processing and the data search processing in the buffer area in parallel by canceling the data transfer processing.