JPH03229336A - Disk cache system - Google Patents

Abstract

PURPOSE:To efficiently use a disk cache memory by providing an access history holding part, and redividing the inside of the disk cache memory at every channel in accordance with the contents of the access holding part. CONSTITUTION:An access history holding part 20a holds how many times a disk device 21 in charge of by itself is accessed, and whenever the disk device 21 is accessed, its value is updated one by one. In such a state, by referring to an access history display part 20a at an arbitrary time, the access history information of this disk cache memory 5 is recognized, and based on a result of recognition, a divided using area of the disk cache memory 5 is changed. Accordingly, to a channel whose using frequency is always the highest, the memory area of a large capacity is allocated, and to a channel whose use frequency is low, a memory area of a small capacity is allocated. In such a manner, the disk cache memory 5 can be efficiently used.

Description

[Detailed Description of the Invention] [Summary] Regarding a disk cache system when disk cache memory is used by multiple CPUs, the purpose of this invention is to use multiple disk cache control channels and to efficiently use the disk cache memory. In a disk cache system consisting of a plurality of disk devices whose data writing and reading are controlled by these disk cache control channels, and a disk cache memory whose area is divided and used according to the number of disk cache control channels. , an access history storage unit is provided in each disk cache control channel to store a history of how many times the relevant disk device has been accessed, and the access history storage unit is referred to at any time to recognize access history information of this disk cache memory. The system is configured to change the divided usage area of the disk cache memory based on the recognized result.

[Industrial Application Field] The present invention relates to a disk cache system when a disk cache memory is used by multiple CPUs, and more specifically, the present invention relates to a disk cache system in which a disk cache memory is used by multiple CPUs, and more specifically, the present invention relates to a disk cache system in which the capacity of the disk cache memory is appropriately divided and allocated to multiple disk cache control channels. Concerning the disk cache system to be used.

[Prior Art] A disk cache system is effective as a means for improving the processing performance of a computer system. FIG. 3 is a conceptual diagram of a conventional disk cache system. The CPUI reads data from the disk device 3 via the disk cache control channel 2. The read data is stored in the main storage device 4 and also in the disk cache memory I75.

Thereafter, when the CPU reads data at the same address in the disk device 3, the disk cache control channel 2 notifies the CPU that the same data is stored in the disk cache memory 5. CPU] reads data from the disk cache memory 5 and processes it. In this way, by using the disk cannon system, frequently used data can be read from the disk cache memory 5, thereby improving processing speed.

On the other hand, if a disk cache system is constructed by equipping multiple disk cache control channels, further performance improvement can be expected. FIG. 4 is a configuration block diagram of a disk cache system in which a plurality of disk cache control channels are connected. Components that are the same as those in FIG. 3 are designated by the same reference numerals. The system shown in the figure has CPU10.
A plurality (n) of disk cache control channels 11 and disk devices 12 are provided.

In accordance with this, the disk cache memory 5 is divided into blocks of 81 to Bn for each channel, for example, #1
The system uses block B1 of the disk cache memory 5 as a disk cache memory. Memory blocks 81 to Bn are divided into areas of predetermined capacity according to the frequency of use of each channel.

The disk cache control channels of each channel can share one disk cache memory 5.

[Problems to be Solved by the Invention] However, once the disk cache memory 5 is divided and allocated to each disk cache control channel 11, the capacity of the disk cache memory that can be used by each disk cache control channel 11 is Since it is fixed, if the conditions of jobs executed on the computer system change, the frequency of use of each disk cache memory may become uneven, and it is not necessarily the case that each disk cache control channel 11 is the most effective. The memory allocation will not be such that it can operate normally. As a result, memory usage efficiency deteriorates.

The present invention has been made in view of such problems, and an object of the present invention is to provide a disk cache system that can efficiently use disk cache memory.

[Means for Solving the Problems] FIG. 1 is a block diagram of the principle of the present invention. Components that are the same as those in FIG. 3 are designated by the same reference numerals. In the figure, 20
5 is a plurality of disk cache control channels; 21 is a plurality of disk devices whose data writing and reading are controlled by these disk cache control channels 20;
is a disk cache memory whose area is divided and used according to the number of disk cache control channels 20. Reference numeral 20a denotes an access history holding unit that stores a history of how many times the disk device 21 has been accessed, and is provided in each disk cache control channel 20.

[Operation 1] The access history holding unit 20a holds information on how many times the access history holding unit 20a has been accessed by itself or by the disk device 21 in charge. In other words, the access history holding unit 20a updates its value by 1 each time the disk device 21 is accessed. Then, at any time, the access history holding unit 20a is referred to and the access history information of this disk cache memory 5 is recognized.
The divided usage area of the disk cache memory 5 is changed based on the recognized result. As a result, a large capacity memory area is always allocated to the most frequently used channel, and a small capacity memory area is allocated to the least frequently used channel.

In this way, the disk cache memory 5 can be used efficiently.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention. Components that are the same as those in FIGS. 1 and 4 are designated by the same reference numerals. In the figure, 4 is a main storage device, 5 is a disk cache memory, and 10 is a CPU provided for each channel.
, 20 is a disk cache control channel provided for each channel, 20a is an access history holding memory provided in each disk cache control channel 20 and holds the number of accesses of the disk device, and 21 is a disk cache control channel for each channel. This is a disk device connected to channel 20. The operation of the system configured as described above will be explained as follows.

The embodiment shown in the figure shows an example in which the disk cache memory 5 is divided at the time of system startup. When the system is started up, the cache memory division information is stored in each disk device from the access history holding section 20a (because the information does not volatilize). When the system is started, one of CPU10 is connected to disk device 21.
The information is read from , and the disk cache memory 5 is divided into blocks B1 to Bn according to the frequency of use of the disk device 21. In this case, a large memory capacity is allocated to channels that are used frequently, and a small memory capacity is allocated to channels that are used less frequently.

If division information is not stored in the disk device 21, the memory capacity is divided by the number of disk cache control channels 20 to divide the memory evenly.

When the system startup is completed and the system starts operating, each disk cache control channel 20
Each time a disk access from U10 is received, a disk cache operation is performed. In addition, each time, the access history (number of disk access requests, read hit rate, write hit rate, cache memory usage size, number of evictions, etc.) is written in the access history holding unit 20a.

Then, at the end of the system operation, this history is notified to the software in response to an access history read command from the software. The software receives the access history of the disk cache memory 5 up to the present from each disk cache control channel 20, compares the data, creates disk cache memory partition information for the next system startup, and Store it in one of 21.

In the embodiments described above, the capacity of the disk cache memory 5 is changed by software creating disk cache memory division information. This division of the disk cache memory 5 may be executed in response to a disk cache memory re-division request issued by software at any time during system operation. When this command is received from the software, the disk cache operation is temporarily invalidated, and then each disk cache control channel 20 divides the disk cache memory again based on the usable capacity specified by the software. After that, enable disk cache operation.

Although the above-mentioned embodiment shows the case where the disk cache memory 5 is provided separately from the main storage device 4, the present invention is not limited to this, and the disk cache memory 5 may be provided within the main storage device 4. Good too. In this case, a specific area of the memory map must be designated as a disk cache memory area.

[Effects of the Invention] As described above in detail, according to the present invention, an access history holding section for storing the history of disk device accesses is provided in the disk cache control channel, and the disk cache memory is stored according to the contents of this access holding section. By re-dividing the data for each channel, the disk cache memory can be used efficiently.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle of the present invention, Fig. 2 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 3 is a diagram showing the configuration of a conventional disk cache system, and Fig. 4 is a diagram showing the configuration of a conventional disk cache system. FIG. 1 is a block diagram illustrating the configuration of a disk capture system. In FIG. 1, 5 is a disk cache memory, 20 is a disk cache control channel, 20a is an access history holding unit, and 21 is a disk device.

Claims (1)

[Claims] A plurality of disk cache control channels (20), a plurality of disk devices (21) whose data writing and reading are controlled by these disk cache control channels (20), and a disk cache control channel (20). ), the area of which is divided according to the number of disk cache memory (
5), an access history storage unit (20a) is provided in each disk cache control channel (20) to store a history of how many times the disk device (21) has been accessed, and an arbitrary At the same time, the access history storage unit (20a) is referred to to recognize the access history information of this disk cache memory (5), and based on the recognized result, the access history information of the disk cache memory (5) is recognized.
) A disk cache system characterized in that it is configured to change the divided usage area of the disk.