JPS5933689A - Data transfer system - Google Patents

Abstract

PURPOSE:To reduce the input/output overhead for transfer of data, by referring to a storage region where the presence or absence is stored for alteration of data of a main storage device to control the transfer of information from the main storage device to an auxiliary storage device. CONSTITUTION:In the contents of an auxiliary storage cache 14 includes the contents of a main storage device 11, a CPU10 refers to a main storage data alteration information storing device 12. Then only an address is transferred via an auxiliary storage control circuit 13 if the data of the device 11 has no alteration. While both the address and data are transferred via the CPU10 to the cache 14 like a case where the cache 14 includes no data of the CPU10 if the data has an alteration. The data is written to an auxiliary storage device 17 from the chache 14 in the same way by referring to an information storage device 16 which stores the presence or absence of data of the CPU10. The input/output overhead is reduced for transfer of data, and the processing speed is increased with above-mentioned minimum necessary information transfer system.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a computer system having an auxiliary storage cache in addition to a main storage device and an auxiliary storage device 6.
The present invention relates to a data transfer method for retaining frequently referenced data in the cache with little input/output overhead.

[Prior art]

The memory hierarchy of the conventional Leopard machine system consists of a main memory cache, a main memory device, and an auxiliary memory device, all of which are managed by a central processing unit (CPU). Therefore, when moving data that has become less frequently referenced from the main memory to the auxiliary memory, if there is no update while it is being held in the main memory, the data itself must be moved to reduce input/output processing. is not subjected to output processing, and only the block in the main 6-pin storage device in which the data is stored is made free. In other words, since the auxiliary storage device originally stores the same data as the main storage device, even if you read the data you want to transfer from the main storage device M'4 and write it to the auxiliary storage device, the data will not be transferred. This is because the result will be the same even if only the process of making the blocks of the main storage device which have been completely stored empty blocks is performed.

However, recently, a cache for an auxiliary storage device has been added to the memory hierarchy, and a system in which an auxiliary storage device cache is managed by an auxiliary memory t@lt control device is becoming common. In this case, the data evicted from the main storage device f-5 to the cache for the auxiliary storage device 6 is normally the quotient data of the reference type IW next to the data stored in the main storage device. However, as in the past, if the data is not transferred to the above-mentioned cat/yu in the 14th time when it has not been changed while it is stored in the storage device, data that is frequently referenced will be stored in the Gatsch for the device. It may become impossible to hold it. on the other hand,
If all of the data were transferred to the auxiliary storage cache every time data to be evicted from the storage device is generated, the problem would arise that the amount of data to be transferred would increase and the overhead would increase.

[Purpose of the invention]

An object of the present invention is to maintain frequently referenced data in the auxiliary storage cache with little human output overhead in a computer system in which an auxiliary storage cache is added to the conventional memory hierarchy. The purpose is to speed up processing.

[Summary of the invention]

In a computer system in which an auxiliary storage cache is added to the conventional memory hierarchy, it is necessary to place frequently referenced data in the auxiliary storage cache and to reduce human output overhead by 41 times.

Storage systems having an auxiliary storage cache include those in which the cache contains all of the same information as the main storage, and those in which it does not. If the contents of the fM device described above are included, there is no need to output the data that has not been changed in main memory, but if the data block is freed up, the auxiliary storage control device will automatically transfer the data back to main memory. If you do not treat it as existing, it will remain in the auxiliary storage cache forever. In other words, the auxiliary storage control device treats the above data as still being referenced frequently, so even if the reference frequency actually becomes low, the auxiliary storage control device loses the opportunity to flush out the above data to the auxiliary storage device, and the data stored in the cache is Become.

Therefore, in this case, Lin? In addition to emptying the cheetah block in the vehicle, it is also necessary to notify the auxiliary rudder that the data does not exist in the main memory.In this invention, in this case, ,
The address of the data to be output and that data are history Y
j [Indicator side indicating that it was not done] Auxiliary rudder 1 only for misfortune
The amount of output data is reduced by sending it to the prepared cache.

On the other hand, when the auxiliary storage cache does not include the contents of the main storage, data that has not been changed in the main storage must also be output.

However, if the data is simply output, the reference frequency of the data will further decrease, and the following problem will occur when outputting to the auxiliary storage device. [41 Since the auxiliary storage device always contains all the data, if there is no data change in the main cIt, there is no need to output it to the auxiliary storage device, and the contents of the auxiliary storage device are changed only when there is a change. do it. However, if the data in the main storage device is simply sent to the cache as described above, it is not possible to identify whether or not the data has been changed. Therefore, in the present invention, when data is output from the main nL2 storage device to the auxiliary storage cache, the data is
Output processing is performed with information indicating whether there have been any changes to the information at the time it was written into the 12 storage device. This allows the auxiliary storage control device to determine whether or not it is necessary to leave the city when exporting data to the auxiliary storage device.

[Embodiments of the invention]

The present invention will be explained below using examples.

The 1st part shows the overall configuration of the present invention, and includes a central processing unit 10, an upper storage device @11, a main memory data change information storage device vi12, an auxiliary storage device 13, an auxiliary storage cache 14, The auxiliary memory cache data variable information storage device 15, the above-mentioned information storage device 16, and the auxiliary rudder 1.shi device 17.In the present invention, the main storage device 1
1, Auxiliary memory gear/yu 14, Auxiliary rudder tφ, Device 17
forms the memory hierarchy ff'i. In a memory hierarchy, the higher level (in this case, the main memory is at the highest level, and the auxiliary memory is at the lower level) usually has a smaller capacity and is faster to access. Therefore, data that is frequently referenced is placed in a higher-level storage device. 1. If there is a sufficient difference in capacity between each level, a method is adopted in which the contents of the lower memory contain the information stored in the upper memory as is. In the present invention, it is assumed that the auxiliary rudder/one-talk device 17 includes all data assuming that the cap is sufficiently thick.

A system in which the auxiliary storage cache 14 includes all the contents of the main storage device 11 and a system in which it does not include the entire contents will be considered.

In this case, if the reference noise 11 is high, it means that the central processing unit 1
This means that the reference frequency of 0 is the quotient, but as a method for selecting data with low reference frequency, for example, the LRU method (Least (, every [
Jsed) is adopted. In the LRU method, the time when the last reference was received from the central processing unit 610 is dI.

The closer it is, the more likely it will be the next reference point. The present invention is based on L11. Although it cannot be limited to the U method, here is VJ: 1st history of the Ming Dynasty, 11
．． 1 (, I will describe the case using the U method. Ding, 1?
, according to the U method, a stack in which data is arranged in order of reference (ifft rate quotient is called L R [1 stack. L )
(,The higher up the U stack is, the more central processing unit 1
The time when 0 was referenced is near M. The data to be placed in the LH and U stacks and each 7 cell in the memory hierarchy to which the present invention is applied are shown in FIGS. 2 and 3. Drawing j
In, A is the content stored in the main papi storage device 11, B
is the content stored in the auxiliary rudder tit j14 cache 14, C is the content stored in the auxiliary rudder 1, i is the content stored in the device 17,
1z.

Figure 2 d2, auxiliary memory cage 71! /1.4 is the case where the above 1- includes the contents of the device 11, and FIG. 3 is the case where J'JA is not outside the building. In each figure, the Lord m
The process of moving data from primary memory to auxiliary memory cache is A.
→ Indicated by I3, auxiliary N[: I111 from memory cache
11 (Pi 1, process to transfer data to nuclear device 17 B→
It's ri14 l in C.

As is clear from this figure, the data evicted from the main storage device 11 must be stored in the auxiliary storage device 11 because it is the data with the next highest reference level after the data in the master storage device 11. It must be held in the storage cache 14.

The main memory data change information storage device 12 includes the main memory 1
Information indicating whether the data in 1 has been changed is stored. For example, if there is a change, it will be O if it is not 1. Kamisukeki ↑ 1 share cache data change information storage head 15
Stores information indicating whether or not the data in the Kamisuke storage cache 14 has been modified while it is in the main memory. The main memory existing information storage device 16 is 1. +B exists, and the data in the auxiliary storage cache 14 is stored in the main FIL”f
Stores information indicating whether it exists in N. Therefore, the contents of the auxiliary memory cache 14 are stored in the main memory 11.
In the case of a method that does not include the contents of , this device 16 is not necessary.

The central processing unit 10 performs management so that a set of data that is referenced by the central processing unit less frequently is stored in the main storage device 11. That is, i111 auxiliary storage i1 control device 1
3 to input necessary data, and manage to output data that is no longer needed. Auxiliary storage control device 1
3 manages a set of data that is most frequently referenced by the central processing unit 10 next to the data stored in the main storage device 11 so as to be stored in the auxiliary storage cache 14. Then, the first input/output processing is performed in response to a request from the central processing unit 10.

Next, the operation of the present invention will be explained with reference to FIG. 4 (5) and al).

(a) of the 41st page 1(A) shows the processing flow of the central processing unit + 110 when the cache 14 from the auxiliary storage 11 includes all of the information stored in the device 11, and (1) of the same figure ) shows the processing flow of the auxiliary storage device (f'l device 13). FIG. The processing flow of the processing device 10 is shown in (h) of the figure.
71 shows the processing flow of the auxiliary storage control device 13. The output processing when the contents of the auxiliary storage cache 14 to be deleted include the contents of the device 6°11 with a capacity of 1ff will be described.

As shown in step 41, the central processing unit 0 determines the output process according to the contents of the main memory data change information storage device 15 when outputting data whose reference frequency has become low. The information in this storage device j61 is updated at the same time when the central processing unit actually changes the data. Data that has been changed in main memory undergoes normal output processing, as shown in step 42. On the other hand, for data that has not been changed, output processing is performed to notify only the address, as in step 43. The auxiliary storage control device 13 handles normal output processing as follows.

When the data and address are received from the central processing unit 10, in this case, since this data has been changed in the main memory, the contents of the auxiliary memory cache data change information storage device 15 are changed as shown in step 44. , and remembers that there was a change in main memory, and then stores it in auxiliary memory until then.
The contents of the data stored in cache 14 are also historical.
Do 1. Then, as shown in step 45, the contents of the main memory existing information storage device 16 are changed to store that the data is no longer in the main memory. On the other hand, if only the address is received, the data has not changed, so the main memory current information storage device 16 is updated to remember that the data is not in the main memory. Take is fine.

A case will be described in which the contents of the auxiliary storage cache 14 do not include the contents of the main storage device 11. In this case, since there is no data to be output in the katsunoyu 14, the data must be output regardless of whether or not it has been changed in the main memory. In accordance with the main memory data change information storage device 12, the central processing unit ``itlo'' adds 1b control information indicating whether or not there is a change to the output data and outputs the data, as shown in steps 46 and 47. The auxiliary storage device 13 stores the received data in the free area of the auxiliary storage cache 14, as shown in step 48. Then, as shown in step 49, whether or not there has been a change in the main memory is stored in the auxiliary storage geared data change information storage device 15 based on the control information.

Output processing from the auxiliary storage cache 14 to the auxiliary storage device 17 is performed when the free space of the auxiliary storage cache 14 becomes less than a certain value, and the auxiliary storage control device 13 determines the reference frequency within the cache 14. Select low data and perform output processing. This process is shown in FIG. Figure 5 (A) is
0-1) shows the process when the auxiliary memory cache 14 includes all the information stored in the main memory 11, and FIG. show.

First, let us discuss the case of the prisoner in Figure 5. In this case, since data included in the main storage device 11 exists in the cache 14, it is necessary to prevent the data from being evicted. Data that is not included in the main memory is found in the existing information storage device 16, and the number (n) of data to be deleted is selected from among them with low reference frequency. Since all of these data are included in the auxiliary storage device 17, only the data that has been changed in the main memory needs to be retrieved.

This determination is performed using the change information storage device 15.

In this way, after selecting the data to be actually written to the auxiliary storage device 17, the paulownia extraction process is performed.

Next, FIG. 5 03) will be described. In this station building,
The contents of the auxiliary storage cache 13 are stored in the main storage 1.
Since the contents of 1 are not included, which data is true?

There is no problem in taking it out. Therefore, it is sufficient to simply select as many pieces of data that are referenced less frequently as necessary.

The following processing is exactly the same as in case (2).

Normally, input/output processing can be accomplished by the auxiliary storage control device 13 receiving input/output commands from the central processing unit 10. The output method described above can be realized by providing new input/output commands. When the auxiliary storage device 13 is used as a disk, the process is as follows. Note that at this time, the auxiliary storage cache 14 is assumed to be a disk cache.

Disk output processing consists of the following four processes, and there are input/output commands corresponding to each process.

The four processes are seek processing, set sector processing, search processing, and data transmission processing. First, a case where data in the disk cache overlaps with data in the main storage device 11 will be described.

In this case, the output method is to send only the data address,
In fact, it was a method that did not transfer data. Seek processing is part of disk output processing.

Set sector processing and search processing serve to indicate the address of data. Therefore, in this case, it is sufficient to add a new command to the data transfer command that indicates that even if the disk control device receives the command, no data transfer is performed at all. The disk controller knows which data has been output from the main memory during the seek-boot process that has just finished, and by receiving the command not to transmit data,
It is possible to know that the data has not been changed in main memory.

Next, a case will be described in which the data in the disk cache does not overlap with the data in the main memory.

In this case, the output method shown in L7 is to send control information indicating whether or not data has been changed in the main memory at the same time as data is transferred. This can be achieved as follows. If there is no data change, the same output method as before will be used. Then, a command may be provided in the data transfer command that not only instructs to start output processing but also indicates that the data to be output from now on has not been changed in the main memory. When the controller receives this command, it begins the process of receiving data from main memory into the disk cache, but at the same time it knows that the data has not been modified in main memory. Therefore, when writing the data on the disk to the disk later, the data in the main memory without &E can be saved without actually being written.

〔Effect of the invention〕

According to the present invention, in a computer system in which an auxiliary storage cache is added to a conventional memory hierarchy, frequently referenced data can be held in the cache with little input/output overhead. If the auxiliary memory cache contains the contents of the main memory, it is possible to eliminate the need to transfer data that was unchanged in the main memory by providing an output method that sends only the address and no data. It disappears. If such data is X% of the total, it is possible to reduce the time during data transfer by X%.

If the auxiliary memory cache does not contain the contents of the main memory, the control information indicating whether or not there has been a change is output from the auxiliary memory cache to the auxiliary memory by outputting the data. The amount of data can be reduced by X% (again, assuming that the number of publications of unhistorical data is X% of the total 14.).

[Brief explanation of the drawing]

Figure 1 is the overall 5 purchase diagram of the present invention, Figure 2 is the above ↑
Figure 3 shows the data that should be placed in the storage device when the auxiliary storage cache contains the contents, and Figure 3 shows the data that should be placed in the ML storage device when the auxiliary storage cache does not contain the above contents. Figures shown in Figure 4, A3) and Figure 5 (A), C [3
) is a flowchart of the output processing of the method of the present invention.
(:1.”'Representative Patent Attorney Toshiyuki Usuda),,fl-,,.Z 1 Figure 5 (A) (B)

Claims (1)

[Claims] 1. Main origin 'rJt! , the device and the information that this main memory contains or does not contain? an auxiliary storage cache for storing information, an auxiliary storage device for storing information including the contents of the auxiliary syndrome 1 neglect cache, and a central processing unit for managing the reference frequency data so that it is stored in the main storage device. and an auxiliary storage control device that manages data such that the next most frequently referenced data after the data stored in the main storage device is stored in the auxiliary storage device. a first storage area for storing information indicating whether or not there has been a change in the stored data;
The data transfer method is characterized in that the central processing unit controls data to be transferred from the main storage device to the auxiliary storage control device by referring to information stored in the first storage area. 2. In the method described in item 1, when there is no change in the data stored in the main memory, the address of the data to be transferred is sent, and when there is a change, both the data and address are sent. Characteristic data transfer method. 3. In the method of item 2, the second memory stores information indicating whether or not the data currently in the auxiliary memory cache has been changed while being stored in the main memory.
1tT area, and the auxiliary storage control device updates the data in the auxiliary storage cache and also updates the information in the second storage area when it receives both the address and the data. Transfer method. 4. In the method of item 2, the auxiliary storage control device has a third storage area that stores information indicating whether or not the data currently in the auxiliary storage cache is also in the main storage; A data transfer method characterized in that the third storage area is updated when both the address and the address are received. 5. A data transfer method according to item 1, characterized in that control information indicating whether or not there has been a change while being stored in the main storage device is added to the data before the data is transferred. 6. In the method of the fifth koma, the data currently in the cache for ``L, rn + auxiliary notes'' is the main one, and the data is not changed while stored in the sieve. The second memory that stores the information shown is cured and the auxiliary memory control device (d1
At the same time as receiving the data and storing it in the 1111 million cache,
In the method of item 7, item 3 or item 6, the +ft information of the second storage area is indicates that there has been a data change, the auxiliary nr from the auxiliary H1i storage cache: i=
A data transfer method characterized in that when data is actually output to a device and there is no shortage, the data area of the cache is set to a free area of %4.