JPH02287849A - Disk cache control method and disk cache device - Google Patents

Abstract

PURPOSE:To improve the overall throughput of a system by deciding the address range of an available directory memory for each task which is carried out in the system and then deciding an entry to update only the entry group in a direct memory in a range assigned to the corresponding task in a mishit state. CONSTITUTION:The comparators 13-1 - 13-n compare the process ID in the disk access information 11 with the registered process IDs in the task control registers 12-1 - 12-n respectively. When the coincidence is obtained from the comparison, a hit signal HIT1 is outputted from an OR gate 14. Then the address range of an available directory memory 17 is decided for each task which is carried out in an operating system corresponding to the multi-user/ multi-task. In a mishit state an entry is decided to update only the entry group in the memory 17 within a range assigned to the corresponding task. Thus an updating operation is carried out. As a result, the hit rate is improved and the overall throughput of the system is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a disk cache control method and a disk cache device in a disk control device compatible with a multi-user/multi-task operating system.

(Prior Art) Recent disk control devices, such as magnetic disk control devices, have two types of memory: a data memory (disk cache memory) in which a copy of a portion of a disk is stored in blocks (disk blocks, cache blocks); Many disk cache devices are equipped with a directory memory in which index information (disk address tag) of a disk address corresponding to placed disk block data is registered. Conventionally, in this type of disk cache device, in response to a disk access to a physical or logical disk address requested by the system (host device),
) method, FIFO (First-In
It has been common practice to update (replace) the contents of the corresponding entry in the directory memory using a replacement rule such as the First-Out method. In this method, for example, in an operating system that supports multi-user/multi-tasking, a task that requires large-volume and frequent disk access may be forced to sacrifice other tasks that operate on specific disk areas, causing the disk cache to become unavailable. In addition to not being able to benefit from this, there was a problem in that really necessary cache blocks were evicted from the directory memory due to streaming data that did not require caching, such as simple copying.

(Problems to be Solved by the Invention) As mentioned above, in the conventional disk cache device, the disk cache device only follows the disk address requested by the system.
Since the content of the corresponding entry in the directory memory is updated using the LRU method, FIFO method, etc., there is a problem in that the hit rate for disk access requests from an operating system compatible with multi-user/multi-task is low.

Therefore, the problem to be solved by this invention is to make it possible to significantly increase the hit rate for disk access requests from an operating system that supports multi-user/multi-tasking, thereby improving the throughput of the entire system. be.

[Structure of the Invention] (Means for Solving the Problem) The disk cache control method of the present invention includes a data memory in which a copy of part of the data on the disk is stored in block units; In a disk cache device equipped with a directory memory in which data block directory information is registered, the usable directory memory address range is determined for each task executed by the system and corresponds to the disk address requested by the system. In the event of a miss where the data block to be updated does not exist in the data memory, the entry to be updated is determined by targeting only the group of entries in the directory memory that are allocated to the corresponding task. be.

Further, the disk cache device of the present invention has n task management registers in which process identifiers indicating tasks are registered, and each of the n task management registers forms a pair and is registered in the corresponding task management register. n directory address registers are registered with address range information that specifies the address range of the directory memory to be allocated to the task indicated by the process identifier, and the disk access information created in response to a disk access request from the system and given by the system. A process identifier comparing means compares the included process identifier with the registered contents of each of the n task management registers, and based on the comparison result of this process identifier comparing means, it is determined that the process identifier matches the process identifier contained in the disk access information. register selection means for selecting a directory address register corresponding to the task management register whose registered contents are registered; and disk access information for a group of entries in the directory memory in the range indicated by the directory address register selected by the register selection means. If a miss is determined by this directory check means, a block block corresponding to the disk address included in the file exists in the data memory to determine whether there is a hit or a miss. 2. The present invention is characterized in that it is provided with updating means that determines entries to be updated and performs update processing only on a group of entries in the directory memory in the range indicated by the selected directory address register. When it is shown that the process identifier included in the disk access information does not match any of the registered contents of the n task management registers, the updating means predetermines one of the n task management registers. The contents of the selected task management register are updated to the process identifier included in the disk access information, and the contents of the directory address register corresponding to the task management register are updated to the disk access information. It is configured to update address range information for specifying the address range of the directory memory to be allocated to the task indicated by the included process identifier.

(Function) According to the above configuration, the address range of the available directory memory is determined for each task executed by the operating system that supports multi-user/multi-tasking, and the address range requested by the system is In the event of a miss in which the corresponding data block does not exist in the data memory, the entries to be updated are determined only for a group of entries in the directory memory within the range assigned to the corresponding task, and an update operation is performed. That is, all the contents of the directory memory entry group assigned to other tasks are saved. Therefore, disk access for streaming data that does not require caching, such as a simple copy, associated with the execution of the above task may discard (evict) data in a disk block that is required by another task. There is no need to worry about it getting lost.

(Embodiment) FIG. 1 shows a block configuration of a disk cache device according to an embodiment of the present invention. In this embodiment, it is assumed that the disk cache device shown in FIG. 1 is provided within a magnetic disk control device.

In FIG. 1, 11 is disk access information given in response to a disk access request from the system (operating system of the host device), including a process identifier (hereinafter referred to as process ID) indicating a task (process) executed by the system; and a disk address consisting of a cylinder address, head address, and sector address. 12-1 to 12-n are process IDs
task management register in which index information of 13-1 is registered;
~13-n is process I in disk access information ll
A comparator 14 compares the contents of the task management registers 12-1 to 12-n with the contents of the task management registers 12-1 to 12-n. Process I that matches the process ID in 11
This is an OR gate that outputs a hit signal HITI (indicating whether D is registered in any of the task management registers 12-1 to 12-n).

15-1 to 15-n are task management registers 1.2-1 to 15-n.
This is a directory address register in which directory address range information for specifying the address range (entry range) of the directory memory 17 (to be described later) to be allocated to the task indicated by the contents of 12-n is registered. This directory address range information consists of a lower limit directory address Low indicating the lower limit of the range and an upper limit directory address High indicating the upper limit of the range. The directory address range assigned to each task is determined, for example, at the time of initial setting. 16 is a selector (hereinafter referred to as WAY selector) that selects one of the registered contents of the directory address registers 15-1 to 15-n according to the output signals (comparison results) of the comparators 13-1 to 13-n. ), 17 is a data memory (disk cache memory) which will be described later.
This is a directory memory in which directory information including index information (disk address tag) of a disk address corresponding to disk data (disk block data, here sector data) placed in each block of 20 is registered. The directory address range information selected by the WAY selector 16 is used to specify the address range of the directory memory 17 to be accessed.

Reference numeral 18 indicates a group of directory information taken out from the directory memory 17 in accordance with the specification of directory address range information selected by the WAY selector 16, and reference numeral 19 indicates data in which a copy of a portion of disk data is placed in units of disk blocks of a predetermined size. It's memory. Data memory 19
The block is designated by each disk address tag in the directory information group 18 selectively retrieved from the directory memory 17. 20 is directory information group 18
Each disk address tag and disk access information 1 inside
A comparator 21 outputs an active hit signal HIT2 indicating that the corresponding disk block data exists in the data memory 19 when the two are equal.
a data selector that selects the data of the block in the data memory 19 (disk block data) specified by the corresponding disk address tag when T2 is output;
22 is a control mechanism that controls the entire disk cache device. The control mechanism 22 selects one of the task management registers 12-1 to 12-n when the hit signal HITI indicates a miss, and controls the selected task management register and the directory address register corresponding to the same register. and select one of the entries in the directory memory 17 within the range specified by the directory address register selected by the WAY selector 16 when a miss is disabled by the hit signal HIT2. It also has an update function to update the selected end and also the contents of the data memory 19.

Next, the operation of the configuration shown in FIG. 1 will be explained using disk read access as an example. First, it is assumed that a disk read access request including disk access information 11 is issued from the system to a magnetic disk control device having the disk cache device shown in FIG. The process ID in the disk access information 11 from the system is the comparator 13-1 to 13.
-n is commonly supplied to one input. Comparator 13-1
The other input of ~13-n is the task management register 12-n.
The process IDs registered in 1 to 12-n are respectively supplied. The comparators 13-1 to 13-n compare the process ID in the disk access information 11 and the registered process ID in the task management registers 2-1 to 12-n, and if they match, the Outputs a logic "1" signal.

When a logical MIH output signal is output from one of the comparators 13-1 to 13-n, the OR gate 14 selects a process ID that matches the process ID in the disk access information 11.
An active hit signal HI Tl indicating that the task is registered (hit) in any of the task management registers 12-1 to 12-n is output. At this time, the WAY selector 16 selects whether the comparator 13-i is outputting a logic "1" signal (that is, has detected a hit) in accordance with the output signals (comparison results) of the comparators 13-1 to 13-n. (1≦1≦n)
5-n) directory address register 15-
Select the registered content of No. 1, that is, the directory address range information. The directory address range information selected by this WAY selector 16 is the disk access information 1.
Specifies the address range of the directory memory 17 allocated to the task indicated by the process ID in 1,
With this specification, the directory information group 18, which is the contents of all entries in the corresponding address range (entry range) of the directory memory 17, is transferred to the directory memory 17.
7.

Each disk address tag in the directory information group 18 retrieved from the directory memory 17 is supplied to one input of the comparator 20 one by one, for example. Comparator 2
The other input of 0 is supplied with the disk address in the disk access information 11 from the system. Comparator 20
sequentially compares the disk address tag from the directory memory 17 with the disk address (which may be a predetermined part of the address) in the disk access information 11, and only if the two are equal, indicates that the corresponding disk block data exists in the data memory 19. It outputs an active HI signal HIT2 indicating that it is to be executed (hit). When the comparator 20 outputs the hit signal HI T2 of logic ff "1", that is, the comparator 20 outputs the hit signal HI
When the target data is detected, the data in the block in the data memory 19 corresponding to the disk address tag (in the directory information group 18) used for hit detection or the registered entry in the directory memory 17, immediately becomes the target data. Selected by the selector 21.

On the other hand, if a hit is not detected in any of the comparators 13-1 to 13-n, that is, if the hit signal HITI output from the OR gate 14 is not active, the task management register is 12-
The task management register [-j<1≦j≦n] that has been used most recently among the task management registers 1 to 12-n is selected, and the contents of the selected task management register 12-j are included in the disk access information 11. is updated to the process ID of Along with this update process, the contents of the directory address register 15-j corresponding to the schedule management register 12-j specify the address range of the directory memory 17 allocated to the task indicated by the process ID in the disk access information 11. Updated directory address range information for. The above update processing is performed by the control mechanism 22. Then, the contents of the entries in the directory memory 17 (directory information group] 8) in the range indicated by the updated directory address range information are retrieved, and from then on, the WAY selector 16 selects the address register 15-1.
~15-n is selected and directory information group 18
The same operation as above is performed.

Similarly, if the comparator 20 does not detect a hit,
That is, the signal h output from the comparator 20 is
If T2 is not active, for example, LRU
Depending on the method, the contents of the entry most recently used among the group of entries in the directory memory 17 within the range specified by the directory address range information selectively output from the WAY selector 16, or the disk in the disk access information 11. Updated with new directory information including addresses. Along with this update process, this directory memory 1
The contents of the block in the data memory 19 corresponding to the entry in the disk access information 11 are updated to the data on the disk (disk block data) indicated by the disk address in the disk access information 11. The above update processing is performed by the control mechanism 22.

[Effects of the Invention] As detailed above, according to the present invention, multi-user/
For each task executed in an operating system that supports multitasking, the address range of the available directory memory is determined, and in the event of a miss in which the data block corresponding to the disk address requested by the system does not exist in the data memory, the system will respond accordingly. Since the entries to be updated are determined and updated only for the group of entries in the directory memory that are allocated to the task, even if the above task involves a large number of frequent disk accesses, However, there is no risk that the directory memory entries allocated to other tasks will be updated, and therefore there is no risk that data in disk blocks needed by other tasks will be evicted. The hit rate for disk access requests from compatible operating systems can be greatly increased, and the throughput of the entire system can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a disk cache device according to an embodiment of the present invention. 11...Disk access information, 12-1~l2-
n...Task management register, 13-1 to 13-n,
20... Comparator, 15-1 to 15-n... Directory address register, 16... WAY selector, 17
. . . Directory mesori, 18 . . . Direct information group, 19 . . . Data memory, 21 . . . Data selector, 22 . . . Control mechanism. Applicant's agent Patent attorney Takehiko Suzue

Claims (3)

[Claims] (1) In a disk cache device equipped with a data memory in which a copy of some data on the disk is stored in block units, and a directory memory in which directory information of the data blocks stored in this data memory is registered, the system The usable address range of the directory memory is determined for each task executed by the system, and in the event of a miss in which the data block corresponding to the disk address requested by the system does not exist in the data memory,
A disk cache control method characterized in that an entry to be updated is determined only from the group of entries in the directory memory that are allocated to a corresponding task. (2) In a disk cache device equipped with a data memory in which a copy of a portion of data on the disk is stored in block units, and a directory memory in which directory information of the data blocks stored in this data memory is registered, a task is performed. n number of task management registers in which process identifiers indicating the above are registered; n directory address registers in which address range information specifying the address range of the directory memory is registered; a process identifier included in the disk access information given by the system in response to a disk access request from the system; A process identifier comparison means that compares each registered content of the task management register, and based on the comparison result of this process identifier comparison means, the task management register whose registered content matches the process identifier included in the disk access information. register selection means for selecting said directory address register corresponding to said register address register; and register selection means for selecting said directory address register corresponding to said register address register; a directory check means for determining hit/miss hit by checking whether a data block corresponding to a disk address exists in the data memory; and when a miss hit is determined by the directory check means, the register selection means updating means for determining and updating the entries to be updated only for the group of entries in the directory memory in the range indicated by the directory address register selected by the disk cache device. . (3) The updating means determines that the comparison result of the process identifier comparing means indicates that the process identifier included in the disk access information does not match any of the registered contents of the n task management registers. If so, one of the n task management registers is selected according to a predetermined replacement rule, the contents of the selected task management register are updated to the process identifier included in the disk access information, and the task management register is updated to the process identifier included in the disk access information. The content of the directory address register corresponding to the register is updated to address range information for specifying the address range of the directory memory to be allocated to the task indicated by the process identifier included in the disk access information. A disk cache device according to claim 2.