JPH03296841A - Cache control system - Google Patents

Abstract

PURPOSE:To leave effective data blocks in a cache memory as much as possible and to improve a cache hit rate by connecting all buffer cache blocks to a free list at the time of deleting a certain file and lowering all priority levels down to the lowest levels. CONSTITUTION:A file control means 1 outputs information relating to file deletion. A free buffer control means 4 receiving the information connects a buffer header to the free list 120 so that its buffer cache block is made a free state and allocated to another data block. A cache block priority control means 7 lowers the priority of the cache block header down to the lowest level and immediately allocates the disk cache block to another data block.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cache control method, and particularly to a cache control method for controlling a buffer cache memory and a magnetic disk cache memory in a file system of a computer system.

[Conventional technology]

In the file system of a computer system, part of the memory is used as a buffer cache memory for the purpose of reducing the difference between the speed of data block transfer between memories and the speed of data block transfer between the magnetic disk device and memory. In some cases, the memory is used as a magnetic disk cache memory, and another part of the memory is used as a magnetic disk cache memory.

In such a file system, when a data block is transferred from the magnetic disk device to the user program memory space based on a read request for a certain data block, the data block read from the magnetic disk device is once magnetically transferred. It was stored on the disk cache memory, further stored on the buffer cache memory, and then transferred to the user program memory space.

As a result, when a read request for the same data block occurs again, if the data block remains on the buffer cache memory (in the case of a buffer cache) or even if it does not remain on the buffer cache memory, the magnetic disk If it remains in cache memory (for disk cache hints)
, block data can be transferred from the magnetic disk device to the user program memory space by transferring it from either the buffer cache memory or the magnetic disk cache memory to the user program memory space (transfer from the magnetic disk device is not required). ), it was possible to shorten the time required to transfer the data block (data input/output).

In the cache control method that controls the buffer cache memory and magnetic disk cache memory in such a file system, the buffer cache block (an area allocated to one of the data blocks) which is a component of the buffer cache memory In addition, disk cache blocks (an area allocated to a positive integer multiple of data blocks for boat fishing), which is a component of a magnetic disk cache memory, are managed in consideration of their frequency of use.

In other words, buffer headers containing management information for buffer cache blocks on the buffer cache memory are managed by a hash table and a free list (see Figure 2 <a> and (b)). The frequency of use of a buffer cache block is taken into consideration by connecting the buffer headers of buffer cache blocks that are not used at that time (no valid data blocks are stored).

Note that the values of each entry in the hash table (Figure 2 (a)
) and (b), 0-N (N is a positive integer)) is
A block of data blocks stored in the buffer cache block corresponding to the buffer header connected to that entry (the connection is formed by the previous buffer header or entry having a pointer to the next buffer header) It corresponds to the remainder when a number is divided by a fixed value.

Further, the cache link header having management information of disk cache blocks on the magnetic disk cache memory is managed by a priority table (see FIGS. 3(a) and 3(b)). Here, in the priority table, the priority of the cache block header corresponding to the disk cache block on the magnetic disk cache memory is determined according to the frequency of use of the disk cache block (Figure 3 (a)
and 0 to M (M is a positive integer) in (b) are determined, and the frequency of use of the disk cache block is taken into consideration.

Conventionally, in this type of cache control method, control caused by actual data input/output requests (data block transfer requests) (writing data blocks to buffer cache memory or magnetic disk cache memory, buffer cache memory or magnetic disk cache Regulations for reading data blocks from memory W) L,
or has not been done.

Therefore, when a file is deleted under the control of the file control means, if the data block used by that file exists on the buffer cache memory or magnetic disk cache memory,
A data block is used until the buffer cache memory or magnetic disk cache memory runs out of space and the buffer cache block or disk cache block allocated to that data block is replaced by another data block. continued to be allocated to buffer cache blocks or disk cache blocks.

[Problem to be solved by the invention]

In the conventional cache control method described above, if a data block used by a file is present in the buffer cache memory or magnetic disk cache memory when the file is deleted, the data block is immediately deleted. Since there is no control over the allocated buffer cache block or disk cache block, the buffer cache block corresponding to the buffer header that is not managed by the free list or the cache connected to the entry indicating a high priority in the priority table If a file related to a data block stored in a disk cache block corresponding to a block header is deleted, the data block that is no longer needed will be stored in the buffer cache memory or magnetic disk for a longer time than other data blocks. It will remain in the cache memory (
(A valid data block may be evicted first), and the cache hint rate in buffer cache memory and magnetic disk cache memory is poor.

In view of the above, an object of the present invention is to connect all buffer cache blocks in which data blocks used by a certain file are stored when the file is deleted to a free list, and to remove such data. To provide a cache control method that improves the cash hit rate by leaving as many valid data blocks as possible on a buffer cache memory or magnetic disk cache memory by setting all the priorities of disk cache blocks in which blocks are stored to the lowest level. There is a particular thing.

[Means to solve the problem]

The cache control method of the present invention includes a file control means that performs management control such as creation and deletion of files on a magnetic disk device, a file that is managed and controlled by this file control means, and a data block used for the file. a file block control means that manages the correspondence between the user program memory space and the buffer cache memory and controls the transfer of data blocks between the user program memory space and the buffer cache memory; a free buffer control means that connects a buffer of a buffer cache block allocated to a data block used for the file to a free list when a deletion notification is received;
Based on the control by the huff table control means and the free buffer control means, a buffer cache block to be used for data block transfer is selected and provided to the file block control means, and a buffer cache block is selected and provided to the file block control means. A buffer cache control means that controls the transfer of data blocks, and controls the priority of disk cache flocks managed in a priority table, so that when a file deletion notification is received, the data blocks used for that file are a cache block priority control means for controlling the assigned disk cache block to have the lowest priority; and a disk cache to be used for data block transfer based on control by the magnetic disk cache block control means and the cache block priority control means. magnetic disk cache control means for selecting a block and providing it to the buffer cache control means and controlling the transfer of data blocks between the magnetic disk cache memory and the magnetic disk device using the magnetic disk device control means; and file management information transmitting means for providing a notification regarding deletion of a file to the free buffer control means and the cache block priority control means when the file is deleted by the file control means.

[Effect]

In the cache control method of the present invention, the file control means performs management control such as creation and deletion of files on the magnetic disk device, and the file block control means is used for the files and files whose management control is performed by the file control means. The free buffer control means manages the correspondence with the data blocks that are used and controls the transfer of data blocks between the user program memory space and the buffer cache memory, and the free buffer control means uses unused buffer cache blocks when transferring data blocks. When a file deletion notification is received, the buffer cache control means connects the buffer header of the buffer cache block allocated to the data block used for that file to the free list, and the buffer cache control means performs hash table control. The buffer cache flow to be used for data block transfer based on the control by the free buffer control means and the free buffer control means.
7 is selected and provided to the file block control means to control the transfer of data blocks between the buffer cache memory and the magnetic disk storage memory, and the cache block priority control means selects and provides the file block control means with respect to the disk cache blocks managed in the priority table. When a file deletion notification is received, the magnetic disk cache control means controls the priority of the disk cache block assigned to the data block used for that file to be the lowest. Based on the control by the disk cache block control means and the cache block priority control means, a disk cache block to be used for data block transfer is selected and provided to the buffer cache control means, and the magnetic disk device control means is used to select the disk cache block to be used for data block transfer, and to use the magnetic disk device control means to select the disk cache block to be used for data block transfer. The file management information transmission means controls the transfer of data blocks to and from the magnetic disk device, and when a file is deleted by the file control means, the file management information transmission means sends a notification regarding the deletion of the file to the free buffer control means and the cache block priority. control means.

〔Example〕

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the cache control method of the present invention. means 3, free buffer control means 4, magnetic disk cache control means 5, magnetic disk cache block control means 6,
Cache block priority control means 7, hash table control means 8, file block control means 9, magnetic disk device control means 10, priority table 11, hash table 12 (free list 120 is attached) and buffer header group 1
3, cache block header group 14, user program memory space 15, and buffer cache memory 1
6, a magnetic disk cache memory 17, and a magnetic disk device 18.

FIGS. 2(a) and 2(b) are diagrams showing a specific example of how the buffer header group 13 is managed by the hash table 12 and free list 120. Buffer header G connected to free list 120 in FIG. 2(a)
Buffer cache blocks corresponding to and H are in a free state S (unused state jli), and when a request to use a buffer cache block occurs, these buffer cache blocks are allocated first.

FIGS. 3A and 3B are diagrams showing specific examples of how the cache block header group 14 is managed by the priority table 11. In FIG. 3(a), cache block header A connected to entry O
′ has the lowest priority, and the disk cache blocks corresponding to cache block headers E′ and F′ connected to entry M have the highest priority. Allocated to data blocks.

Next, the operation of the cache control system of this embodiment configured as described above will be explained.

First, the operation when a data block is transferred based on file creation or data input/output to an existing file under the control of the file control means 1 and the file block control means 9 will be described.

The file block control means 9 is used to transfer a specific data block to the buffer cache control means 3 in response to a request for file creation or data input/output to a file from a user program via the file control means 1. request a buffer cache block on buffer cache memory 16 that is available.

Upon receiving this request, the buffer cache control means 3 passes control to the hash table control means 8.

The hash table control means 8 checks the hash table 12 and the buffer header group 13 managed by the hash table 12 to determine whether there is a buffer cache block already allocated to the data block.
Browse and explore.

If it is determined that there is a buffer cache block already allocated to the data block, the hash table control means 8 sends a message to the buffer cache control means 3 and the file block control means 9 (via the buffer cache control means 3). Passes a pointer to the buffer header corresponding to the buffer cache block.

If it is determined that there is no buffer cache block allocated to that data block yet, the hash table control means 8 controls the buffer cache control means 3.
Control is passed to the free buffer control means 4 via.

The free buffer control means 4 refers to the free list 120 and transfers a pointer to the buffer corresponding to the unused buffer cache program on the buffer memory 16 to the buffer cache control means 3 and the file. It is passed to the block control means 9 (via the buffer cache control means 3).

The file block control means 9, which has received the pointer to the buffer ladder, uses the buffer cache block corresponding to the buffer header to control the data block between the user program memory space 15 and the buffer cache memory 16. Control transfers.

Next, the buffer cache control means 3 requests the magnetic disk cache control means 5 for a disk cache block on the magnetic disk cache memory 17 that can be used for transferring the above-mentioned specific data block.

Upon receiving this request, the magnetic disk cache control means 5 passes control to the magnetic disk cache block control means 6.

The magnetic disk cache block control means 6 checks the cache block header group 14 managed by the priority table 11 via the cache block priority control means 7 to determine whether there is a disk cache block already allocated to the data block. Browse and explore.

If it is determined that there is a disk cache block already allocated to the data file 7, the magnetic disk cache block control means 6 controls the magnetic disk cache control means 5 and the buffer cache control means 3 (magnetic disk cache block control means 6). via control means 5)
a pointer to the cache block header corresponding to that disk cache block.

If it is determined that there is no disk cache block allocated to the data block yet, the magnetic disk cache block control means 6 refers to the priority table 11 under the control of the cache processor 7 disk priority control means 7 and assigns the magnetic disk cache memory 17 A pointer to the cache block header corresponding to the disk cache block with the lowest priority above is passed to the magnetic disk cache control means 5 and the buffer cache control means 3 (via the M1 disk cache control means 5).

The priorities of the disk cache blocks on the magnetic disk cache memory 17 are controlled by the cache block priority control means 7, with frequently used disk cache blocks having a high priority and less frequently used disk cache blocks having a low priority. It is controlled as follows.

The buffer cache control means 3 which has received the pointer to the cache block header corresponds to the disk cache block corresponding to the cache block header and the buffer header received from the hash table control means 8 as described above. The buffer cache block is used to control the transfer of data blocks between the buffer cache memory 16 and the magnetic disk cache memory 17.

Further, the magnetic disk cache control means 5 that has received the pointer to the cache block header uses the disk cache block corresponding to the cache block header to control the communication between the magnetic disk cache memory 17 and the magnetic disk device 18. Transferring data blocks (
Asynchronous writing from the magnetic disk cache memory 17 to the magnetic disk device 18 and magnetic disk device [
18 to the magnetic disk cache memory 17) (performed using control by the Wa disk device control means 10).

Next, the operation when a certain file is deleted under the control of the file control means 1 will be explained.

In this case, since no transfer request is made to the data block used for the file, the free buffer control means 4 and cache block priority control means 7 cannot be called by the procedure described above.

Therefore, the file control means 1 sends a notification regarding the deletion of the file to the free buffer control means 4 and the cache block priority control means 7 via the file management information transmission means 2. data block number, etc.).

The free buffer control means 4 that has received this notification, if there is a buffer cache block allocated to the data block (here, the puffer cache block corresponding to the buffer header F in FIG. 2(a)) ), connect the buffer header F of the buffer cache block to the free list 120 (see FIG. 2(b)), and transfer the buffer cache block to other data blocks as a free buffer cache block. be able to be assigned.

When the cache block priority control means 7 receives the above notification, if there is a disk cache link assigned to the data block (here, the cache block header C' in FIG. 3(a)
8), the cache block header C' of that disk cache block has the lowest priority, and as shown in FIG. 3(b), the cache block header C' has the lowest priority. (the disk cache block corresponding to cache block header C' is allocated to other data blocks before the disk cache block corresponding to cache block header A'), and the disk cache block corresponding to cache block header C' is allocated to other data blocks before the disk cache block corresponding to cache block header A') To enable cache blocks to be immediately allocated to other data blocks.

〔Effect of the invention〕

As explained above, the present invention performs cache control to allocate buffer cache blocks and disk cache blocks that were allocated to data blocks that are no longer needed due to file deletion to other data blocks as soon as possible. It is possible to prevent a situation in which a valid data block is evicted from the buffer cache memory or magnetic disk cache memory while the data block that has become invalid still remains in the buffer cache memory or magnetic disk cache memory. This has the effect of improving efficiency and reducing data input/output time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIGS. 2(a) and (b) explain the manner in which buffer header groups are managed by the Huffsh table and free list in FIG. 1. FIGS. 3(a) and 3(b) are diagrams for explaining the manner in which cache block header groups are managed by the priority table in FIG. 1. In the figure, 1... File control means, 2... File management information transmission means, 3... Buffer cache control means, 4... Free buffer control means, 5... Magnetic disk cache control means, 6 ...Magnetic disk cache block control means, 7.. Cache block priority control means, 8.. Hash table control means, 9.. File block control means, 10.. Magnetic disk device control means, 11. ...Priority table, 12.. Huffsh table, 13.. Buffer header group, 14.. Cache block header group, 15.. User program memory space, 16.. Buffer cache memory, 17.. Magnetic disk cache memory. , 18...Magnetic disk device, 120. Free list. Figure 2 (Q) Figure 2 (b)

Claims (1)

[Scope of Claims] A file control means that performs management control such as creation and deletion of files on a magnetic disk device, and a correspondence between files that are managed and controlled by this file control means and data blocks used for the files. a file block control means for managing the data block and controlling the transfer of data blocks between the user program memory space and the buffer cache memory; a free buffer control means for connecting a buffer header of a buffer cache block allocated to a data block used in the file to a free list when a notification related to the file is received; a hash table control means; and the free buffer control means. A buffer cache that selects a buffer cache block to be used for data block transfer based on control by the buffer cache block and provides the selected buffer cache block to the file block control means, and controls data block transfer between the buffer cache memory and the magnetic disk cache memory. A control means controls the priority of the disk cache block managed in the priority table, and when a notification regarding deletion of a file is received, the priority of the disk cache block assigned to the data block used for the file is determined. Cache block priority control means performs control to make the lowest priority, magnetic disk cache block control means and said buffer cache control means select a disk cache block to be used for data block transfer based on control by said cache block priority control means. a magnetic disk cache control means for controlling the transfer of data blocks between the magnetic disk cache memory and the magnetic disk device using the magnetic disk device control means; and when a file is deleted by the file control means; and file management information transmitting means for providing a notification regarding deletion of the file to the free buffer control means and the cache block priority control means.