JP3710351B2 - Data processing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data processing apparatus including an external storage unit, for example, a hard disk device, and more particularly to delayed writing to the external storage unit.
[0002]
[Prior art]
The magnetic disk device has an advantage that the cost per unit capacity is lower than that of the memory, but has a disadvantage that the access time is longer than that of the memory due to its mechanical operation. Therefore, in the computer system, hierarchical storage is used in which the main memory is composed of an expensive but high-speed semiconductor memory, while the magnetic disk device is used as an external storage device. In hierarchical storage, a difference in access speed between a memory and a magnetic disk device is absorbed using a disk cache mechanism.
[0003]
This conventionally used disk cache is provided by an operating system (OS) on a main body including a central processing unit. When the magnetic disk device is accessed, the disk cache mechanism stores a copy of the accessed address data in the disk cache on the main memory. When a magnetic disk access request to the same address is made, the actual magnetic disk is not accessed, and the read / write to the disk cache on the memory is handled. However, when there is a write request to the magnetic disk, the actual data on the magnetic disk and the data in the disk cache become inconsistent, so the contents of the disk cache are written to the magnetic disk at a predetermined timing. I do.
[0004]
Here, if the main body stops unexpectedly, the contents of the disk cache are not reflected on the magnetic disk, and there is a risk of inconsistency between the two. Therefore, the OS application interface is provided with a type of disk I / O request that does not pass through the disk cache, and important data can be directly written to the magnetic disk device to protect it.
[0005]
FIG. 5 is a block diagram for explaining cache control in a conventional computer. FIG. 6 is a flowchart of disk I / O processing in an OS in a conventional computer, and is a diagram for explaining cache control. When an application program operating on the OS 4 in the main body 2 requests access to the magnetic disk device 6, the type of the request is determined by the request determination logic 8 (S30). The request determination logic 8 determines whether the request type is a normal I / O request made via a disk cache or a direct access request for issuing an I / O request directly to the disk controller 10 without using it. . For example, if the access request issued by the application program APP1 is a normal I / O request, based on the determination S30 in the request determination logic 8, the disk cache memory on the memory 14 via the disk cache logic 12 provided by the OS Is read / written (S32), and the completion of the READ / WRITE is notified to APP1 (S34), and the READ / WRITE request processing from APP1 is completed (S36). The disk cache logic 12 reflects the contents of the disk cache in the memory 14 to the magnetic disk device 6 at a predetermined timing.
[0006]
On the other hand, for example, when the access request issued by the application program APP2 is a direct access request, the OS issues an I / O request directly to the disk controller 10 based on the determination S30 in the request determination logic 8, and the The direct data read / write with the disk device 6 is realized (S38). Upon completion, the APP2 is notified of the completion of READ / WRITE (S34), and the READ / WRITE request processing from the APP2 ends (S36).
[0007]
[Problems to be solved by the invention]
Conventionally, from the viewpoint of protecting important data as described above, a magnetic disk device may be accessed directly from the main body without using a disk cache on a memory. In this case, the actual access time to the magnetic disk device can be seen from the application of the main body, and there is a problem that the processing cannot be performed quickly.
[0008]
The present invention has been made to solve the above-mentioned problems, and it is possible to reduce the access time while avoiding inconsistency in the storage contents of the main body and the magnetic disk device due to the influence of the main body failure or the like. An object of the present invention is to provide a data processing apparatus in which the above is prevented.
[0009]
[Means for Solving the Problems]
The data processing apparatus according to the present invention, the storage control unit, a storage control unit cache memory, whether the data write request to the external storage unit is from a said cache of said main processing unit, from said cache A determination unit configured to determine based on whether or not the data requested to be written is a block unit; and the data determined by the determination unit not to be from the cache is temporarily stored in the storage control unit cache memory Write control means for performing delayed writing to the external storage unit, while writing data determined by the determination means to be from the cache to the external storage unit without going through the storage controller cache memory It has.
[0010]
In the data processing apparatus according to the present invention, the determination unit further performs the determination in consideration of a data size of the data.
[0011]
In the data processing device according to the present invention, the storage control unit determines whether the data requested to be written to the storage control unit cache memory and the external storage unit is from the cache of the main processing unit. Judgment based on the data size, if the data size is less than a predetermined threshold, determine that the data is not from the cache, and if the data size is greater than or equal to the predetermined threshold, the data from the cache A determination unit that determines that the data is not from the cache by the determination unit and temporarily stores the data in the storage control unit cache memory to perform delayed writing to the external storage unit; Means for storing data determined to be from the cache by the storage controller cache memory And write control means for writing to the external storage unit without passing through, and has a.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a schematic block diagram of a computer system for explaining cache control according to an embodiment of the present invention. The main body 50 (main processing unit) of the computer system is basically the same as that conventionally used. That is, the OS 52 performs basically the same processing as the flowchart of FIG. 6 and reads / writes data from / to the magnetic disk device 56 (external storage unit) via the disk controller 54 (storage control unit). Specifically, when an application program operating on the OS 52 requests access to the magnetic disk device 56, the type of the request is determined by the request determination logic 58 (S30). The request determination logic 58 determines whether the request type is a normal I / O request made via a disk cache or a direct access request for issuing an I / O request directly to the disk controller 54 without using it. . For example, when the access request issued by the application program APP1 is a normal I / O request, based on the determination S30 in the request determination logic 58, the memory 62 passes through the OS cache logic 60 that is the disk cache logic provided by the OS. Data is read from and written to the upper disk cache memory (S32). Upon completion of the read / write, APP1 is notified of completion of READ / WRITE (S34), and the READ / WRITE request processing from APP1 is completed (S36). . The contents of the disk cache in the memory 62 are delayed and written to the magnetic disk device 56 at a predetermined timing based on the OS cache logic 60, and the contents are reflected in the magnetic disk device 56.
[0014]
On the other hand, for example, when the access request issued by the application program APP2 is a direct access request, the OS issues an I / O request directly to the disk controller 54 based on the determination S30 in the request determination logic 58 to read / write data. Perform (S38). Upon completion, the APP2 is notified of the completion of READ / WRITE (S34), and the READ / WRITE request processing from the APP2 ends (S36).
[0015]
As described above, the main body 50 issues a write request to the magnetic disk device 56 according to the control of the OS 52. This write request is processed by the disk controller 54. This computer system is characterized by this disk controller 54.
[0016]
The conventional disk controller 10 sequentially writes data to the magnetic disk device 6 when there is a write request from the OS 4. On the other hand, this system includes a storage controller cache memory 64 in the disk controller 54. The control logic unit 66 of the disk controller 54 includes a feature determination logic 68 and a controller cache logic 70 in order to perform control using the storage control unit cache memory 64. Here, the feature determination logic 68 is determination means for determining whether or not the data requested to be written to the magnetic disk device 56 is from the OS 52 cache, and the controller cache logic 70 is not from the OS 52 cache. This is write control means for temporarily storing the determined data in the storage control unit cache memory 64 and performing delayed writing to the magnetic disk device 56, and these operations will be apparent from the following description.
[0017]
FIG. 2 is a flowchart for explaining write control to the magnetic disk device 56 in the disk controller 54. When receiving an access request from the OS 52 to the magnetic disk device 56, the control logic unit 66 starts processing (S80). In the control logic unit 66, the feature determination logic 68 first determines whether or not the request is a write request for data cached in the OS 52 based on the feature of the parameter of the access request (S82).
[0018]
For example, when the data cached by the OS 52 is reflected on the magnetic disk device 56 in response to a normal I / O request of the application program APP1, the control logic unit 66 immediately determines the I based on the determination S82 in the feature determination logic 68. A / O request is issued to access the magnetic disk device 56 (S84). Upon completion, the OS 52 is notified of the completion of READ / WRITE (S86), and the READ / WRITE request processing from the OS 52 ends (S88).
[0019]
On the other hand, in response to the direct access request of the application program APP2, when the OS 52 requests to write data directly to the magnetic disk device 56 without going through the cache of the OS 52, based on the determination S82 in the feature determination logic 68, Data is read from and written to the storage controller cache memory 64 via the controller cache logic 70 (S90). Upon completion of the data read / write completion, the OS 52 is notified of completion of READ / WRITE (S86), and the READ / WRITE from the OS 52 is read. The request process ends (S88). The contents of the storage controller cache memory 64 are delayed and written to the magnetic disk device 56 at a predetermined timing based on the controller cache logic 70, and the contents are reflected in the magnetic disk device 56.
[0020]
Due to the above-described cache in the disk controller 54 performed in addition to the conventional disk cache in the OS 52, the data directly requested by the application program to be accessed is reflected in the magnetic disk device 56 even if a failure occurs in the main body 50. At the same time, the access time to the magnetic disk device 56 is shortened. On the other hand, regarding the data cached in the OS 52, the access speed is secured by the cache in the OS 52, so that the cache in the disk controller 54 is not particularly necessary. Therefore, by not caching the data cached by the OS 52 in the disk controller 54, the required amount of the storage controller cache memory 64 can be suppressed.
[0021]
Next, the feature determination logic 68 will be described. As described above, the feature determination logic 68 is a determination unit that determines whether the request is a write request for data cached in the OS 52 based on the characteristics of the parameter of the access request from the OS 52 (S82). . The access request parameters include the start address and data length of the area to be accessed in the magnetic disk device 56. An access request related to reading / writing between the cache of the OS 52 and the magnetic disk device 56 has the following characteristics.
[0022]
(I) Since the request is in units of blocks, the start address of the parameter of the access request is a multiple of the block.
[0023]
(Ii) Since the request is in units of blocks, the data length of the parameter of the access request is a multiple of the block.
[0024]
(iii) Since the request is for a collective amount of data according to the cache capacity of the OS 52, the data length of the parameter of the access request is relatively large.
[0025]
FIG. 3 is a schematic diagram showing a storage area of the magnetic disk device 56 and an example of an access request. The storage areas 100 to 104 of the magnetic disk device 56 having all the features (i) to (iii) are examples of address ranges that are accessed by access requests related to the cache of the OS 52. For example, the block length is a relatively large size such as 2048 bytes. On the other hand, the storage areas 110 to 114 of the magnetic disk device 56 lacking at least one of the features (i) to (iii) are examples of address ranges accessed by an access request that does not go through the cache of the OS 52.
[0026]
FIG. 4 is a flowchart of the process of the feature determination logic 68. The feature determination logic 68 first determines whether or not the parameter of the access request from the OS 52 has the feature (iii) (S120). If the data length is less than the predetermined threshold value, the feature determination logic 68 passes through the OS 52 cache. It is determined that it has not been performed (S122). On the other hand, if the data length is equal to or greater than the predetermined threshold value, it is next determined whether or not the parameter has the feature (i) (S124), and if the access start address is not a multiple of the block length. Then, it is determined that it does not go through the cache of the OS 52 (S122). On the other hand, if the start address is a multiple of the block length, it is next determined whether the parameter has the above feature (ii) (S126). If the data length is not a multiple of the block length, It is determined that the cache does not pass through the OS 52 (S122). On the other hand, when the data length is a multiple of the block length, all of the above features (i) to (iii) are satisfied, so the feature determination logic 68 uses the cache data of the OS 52 as the access request. It is determined that the request is a write request (S128). In the example shown in FIG. 3, the threshold value of the data length of the condition (iii) is 2 blocks.
[0027]
As described above, in the present embodiment, whether or not the data write request from the main body 50 is related to data via the cache of the OS 52 is determined on the disk controller 54 side based on the characteristics of the access request parameter. can do. In this embodiment, the operation of the OS 52 of the main body 50 may basically remain the same as the conventional one.
[0028]
One feature of the present invention is that it provides means for caching in the disk controller 54 in response to a direct access request to the magnetic disk device 56, that is, a request to write data not cached by the OS 52 to the magnetic disk device 56. It is in. A configuration having this feature can also be realized by a main body OS different from the conventional one. For example, the OS gives information that can identify the access request to the magnetic disk device 56 and the direct access request regarding the data from the cache of the OS to each access request, and the disk controller 54 based on the identification information. The storage control unit cache memory 64 can be configured to control whether or not temporary storage is performed.
[0029]
【The invention's effect】
According to the data processing apparatus of the present invention, the storage control unit that controls the external storage unit such as a magnetic disk device includes the storage control unit cache memory. When the data requested to be written to the external storage unit is not from the cache of the main body OS, the storage control unit cache memory temporarily stores the data and performs delayed writing to the external storage unit. As a result, regarding the data requested directly by the application program, the data contents are reflected in the external storage unit even when a failure or the like occurs in the main body, and the access time to the external storage unit is shortened. That is, according to the present invention, there is an effect that it is possible to both protect data for which a direct access request is made to the external storage unit and shorten the access time.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a computer system for explaining cache control according to an embodiment of the present invention.
FIG. 2 is a flowchart for explaining write control to a magnetic disk device in a disk controller.
FIG. 3 is a schematic diagram showing a storage area on the magnetic disk device and an example of an access request.
FIG. 4 is a flowchart of processing of a feature determination logic.
FIG. 5 is a block diagram for explaining cache control in a conventional computer.
FIG. 6 is a flowchart of disk I / O processing by an OS in a conventional computer, for explaining cache control.
[Explanation of symbols]
50 main body, 52 operating system (OS), 54 disk controller, 56 magnetic disk device, 62 memory, 64 storage control unit cache memory, 66 control logic unit, 68 feature determination logic, 70 controller cache logic.

Claims (3)

In a data processing apparatus including an external storage unit controlled by a storage control unit and a main processing unit including a cache that is controlled by an operating system and performs delayed writing to the external storage unit,
The storage control unit
A storage controller cache memory;
A determination unit that determines whether data requested to be written to the external storage unit is from the cache of the main processing unit based on whether the data requested to be written from the cache is a block unit. When,
The data determined by the determination means as not being from the cache is temporarily stored in the storage control unit cache memory and written to the external storage unit while being delayed from the cache by the determination means. Write control means for writing data determined to be to the external storage unit without going through the storage control unit cache memory;
A data processing apparatus comprising:   The data processing apparatus according to claim 1, wherein the determination unit further performs the determination in consideration of a data size of the data. In a data processing apparatus including an external storage unit controlled by a storage control unit and a main processing unit including a cache that is controlled by an operating system and performs delayed writing to the external storage unit,
The storage control unit
A storage controller cache memory;
Whether the data requested to be written to the external storage unit is from the cache of the main processing unit is determined based on the data size of the data, and when the data size is less than a predetermined threshold Determining means for determining that the data is not from the cache and determining that the data size is from the cache if the data size is greater than or equal to a predetermined threshold ;
The data determined by the determination means as not being from the cache is temporarily stored in the storage control unit cache memory and written to the external storage unit while being delayed from the cache by the determination means. Write control means for writing data determined to be to the external storage unit without going through the storage control unit cache memory;
A data processing apparatus comprising:

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