JPH04235625A - Buffer control system - Google Patents

Abstract

PURPOSE:To attain the input/output of a block to a data base when a device control CPU has the load of 8 low level. CONSTITUTION:A data base 110 is provided together with a buffer 12 which holds the block to be inputted to end outputted from the data base 110. Then a CPU load measuring means 5 is ended to count the number of programs executed within a prescribed time together with a CPU load estimating means 16 which estimetes the load of a CPU based on the measuring result of the means 15, and a buffer control means 14 which performs the input/output of a block to the data base 110 when the CPU load obtained based on the results of both means 15 end 16 is lower then a reference level.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a buffer management system, and more particularly to an input/output management system for blocks of database data stored on a secondary storage device.

0002

[Prior Art] Conventionally, when this type of system outputs data to a database provided on a secondary storage device such as a magnetic disk device, data of a size called a database block is used for database access within the system. buffer, and then output to the database. Normally, the buffer has a capacity that can store multiple blocks, and even if the program execution body requests output, the output is not actually output to the database immediately so as to reduce the number of input/outputs. When the buffer became full or when creating a state called a rest point in the program that allowed the program to backtrack, the data in the buffer was output to the database.

Next, the conventional system will be explained with reference to the drawings.

FIG. 5 is a block diagram showing the configuration of a conventional buffer management system. In the figure, 10 is a processing unit such as a central processing unit, 11 is a secondary storage device such as a magnetic disk that stores a database 110, and 13 is an input/output means. In the processing device 10, a buffer 12 capable of storing a plurality of blocks and a buffer management means 14 are provided.

In such a configuration, the program execution body 1
When a requests the buffer management means 14 to output a block, the buffer control means 14 updates the block on the buffer 12.

[0006] When the buffer 12 becomes full, the buffer control means 14 makes an output request to the input/output means 13, and the input/output means 13
to create space in the buffer 12. Also,
When the program execution body 1a requests to create a static point,
The buffer management means 14 sends the buffer 12 to the input/output means 13.
The input/output means 13 outputs all the contents of the buffer 12 to the database 110.

However, in the conventional buffer management system described above, the contents of the buffer 12 are transferred to the database 110 only when the buffer 12 becomes full or when the program execution unit 1a requests to create a quiet point.
Therefore, even if the load on the CPU (not shown in the figure) is high at that time, the load on the CPU will further increase and the CPU
There was a drawback that the high load state of U was concentrated at one time.

[0008]

OBJECTS OF THE INVENTION The present invention has been made to solve the above-mentioned conventional drawbacks, and its purpose is to provide a buffer management system that can input and output blocks to and from a database when the CPU load is low. It is to be.

[0009]

[Configuration of the Invention] A buffer management system according to the present invention includes:
A buffer management system for a device having a database, a buffer for holding blocks to be input/output to the database, and an input/output means for inputting/outputting the blocks to/from the database, the buffer management system being for controlling the device. The present invention is characterized by comprising a load prediction means for predicting the load on the CPU, and a control means for causing the input/output means to execute input/output of the block to the database when the predicted load value is less than a predetermined value.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a buffer management system according to the present invention, and parts equivalent to those in FIG. 5 are designated by the same reference numerals. In the figure, 11
0 is a database on the secondary storage device 11, 12 is a buffer, 13 is an input/output means for performing input/output between the database 110 and the buffer 12, 14 is a buffer management means, 2
0 is CPU load measuring means 15 and CPU load predicting means 1
6 and a reference value setting means 17;
8 is an output requesting means, and 19 is an output block number changing means.

The buffer management system of this embodiment having such a configuration predicts the load on the CPU of the device in which this system is installed using the load prediction means 20, and intensively updates the database 110 when the load is low. It inputs and outputs blocks to and from the

Next, the operation of actual input/output control will be explained using FIG. 2. In the system shown in FIG. 2, 10 is a processing unit such as a central processing unit, 11 is a secondary storage device such as a magnetic disk that stores a database 110, and 13 is an input/output means. In the processing device 10, a buffer 12 capable of storing a plurality of blocks and a buffer management means 14 are provided.

When the program execution body 1a requests the buffer management means 14 to output a block, the buffer management means 14 updates the block on the buffer 12.

The CPU load measuring means 15 measures the load of a CPU (not shown) at regular intervals. For example, it counts the number of program executables activated during a certain period from a certain time.

The CPU load predicting means 16 calculates a predicted value of the CPU load based on the measured value by the CPU load measuring means 15. For example, if the measurement period is T, the previous measurement value is L, the previous measurement value is M, and the current measurement value is N, the predicted value K is: K=L+(L-M)/T+{(L- M)/T-
(M-N)/T}/T.

The reference value setting means 17 sets a reference value for the CPU load prediction value, at which the output requesting means 18 requests the buffer management means 14 to output a block when the value is less than the reference value.

The output block number changing means 19 sets a reference value of the CPU load such that the number of blocks output by the output requesting means 18 to the buffer management means 14 is changed when the predicted CPU load value or the measured CPU load value is less than that value. do. When the CPU load is less than the reference value, the output block number changing means 19 causes the output requesting means 18 to change the number of blocks to be output requested. That is, when the CPU load is low, it is sufficient to increase the number of blocks and output them intensively.

[0019] As the CPU load, the predicted CPU load value and C
Which of the CPU load measurement values to use is determined by the increase rate of the CPU load measurement values. For example, if the measurement period is T, the previous measurement value is L, the previous measurement value is M, and the current measurement value is N, then the increase rate J of the CPU load measurement value is:
It is determined by J={(LM)/T-(MN)/T}/T. When the increase rate of the CPU load measurement value is positive, the CPU load measurement value is used as the CPU load, and when the increase rate of the CPU load measurement value is negative, the CPU load predicted value is used as the CPU load.

Refer to FIGS. 3 and 4 for the processing flow when the reference value set by the reference value setting means 17 is X and the reference value set by the output block number changing means 19 is Y in the system configured as described above. and explain.

In FIG. 3, first, the CPU load measuring means 15 measures the load of the CPU (not shown) (step 31).
). Then, the CPU load measuring means 15 converts the measured value into CPU
It is sent to the U load prediction means 16 (step 32). The CPU load prediction means 16 calculates a predicted value based on this (step 33). Then, the CPU load prediction means 16 sends the predicted value to the output block number changing means 19 (step 34
).

The CPU load measuring means 15 also sends the measured value to the output block number changing means 19. (Step 35). The output block number changing means 19 determines whether the increase rate of the CPU load measurement value is positive or negative (step 36). When the increase rate is positive, the CPU load measurement value is set as the CPU load (step 37), and when the increase rate of the CPU load measurement value is negative, the CPU load measurement value is set as the CPU load (step 37).
The predicted U load value is set as the CPU load (step 38).

Turning to FIG. 4, if the CPU load is below the reference value Y, the output request means 18 instructs the buffer management means 14 to change the number of blocks to be output to, for example, G (
Step 39→40).

Next, the reference value setting means 17 sends the reference value X to the output requesting means 18 (step 41). The CPU load prediction means 16 also sends the predicted value to the output request means 18 (step 42). If the predicted CPU load is less than the reference value X, the buffer management means 14 is requested to output the block (steps 43→44).

In response to this, the buffer management means 14 issues a block output request to the input/output means 13 (step 45).
). The input/output means 13 outputs the block from the buffer 12 to the database 110 (step 46).

When the buffer 12 becomes full, the buffer control means 14 makes an output request to the input/output means 13, and the input/output means 13 outputs the data to the database 110 and fills the buffer 13. Create space in Further, when the program execution body 1a requests to create a static point, the buffer management means 14
requests the input/output means 13 to output all the contents of the buffer 12, and the input/output means 13 outputs all the contents of the buffer 12 to the database 110.

Note that the above is an example of outputting blocks in the buffer to the database, but conversely, when outputting blocks in the database to the buffer, C
Output can be performed according to the PU load.

[0028]

Effects of the Invention As explained above, the present invention enables block input/output from a buffer to a database to be performed intensively when the CPU load is low by predicting the CPU load, thereby reducing the load on the CPU. Don't concentrate, CP
This has the effect of allowing U to be operated efficiently.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a buffer management system according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram when input/output control is performed by the buffer management system of FIG. 1;

FIG. 3 is a flowchart showing processing operations in the system of FIG. 2;

FIG. 4 is a flowchart showing processing operations in the system of FIG. 2;

FIG. 5 is a block diagram showing the configuration of a conventional buffer management system.

[Explanation of symbols]

12 Buffer 13 Input/output means 17 Standard value setting means 18 Output request means 20 Load prediction means

Claims (2)

[Claims] 1. A buffer management system for an apparatus having a database, a buffer for holding blocks to be input/output to the database, and input/output means for inputting/outputting the blocks to/from the database, comprising: The apparatus further comprises a load prediction means for predicting a load on a control CPU of the apparatus, and a control means for causing the input/output means to input/output the block to the database when the predicted load value is less than or equal to a predetermined value. Features a buffer management system. 2. The load prediction means includes means for measuring a load on a control CPU of the apparatus, means for predicting a load on the CPU based on past measurement results by the load measurement means, and both of these. 2. The buffer management system according to claim 1, further comprising means for changing the number of blocks to be input/output to said database in accordance with a value from said means.