JPH09218824A - Information processing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the use efficiency of cache memory space by providing a means collecting statistical information tuning proper threshold and providing a user with the information and a means updating the threshold from the user, based on statistical information. SOLUTION: A channel control part 31 receives the input/output request of the data of a disk device 2 that a central processing unit 1 issues and executes the request. A drive control part 35 performs the control of the data transfer of the disk device 2 and a storage controller 3. The threshold tuning control part 41 of the tuning processor 4 connected with the storage controller 3 produces cache load statistical information, produces threshold update information, outputs a cache load statistical information and sets threshold. A threshold control memory 42 holds the cache load statistical information necessary for a threshold tuning and holds threshold update information. Within a control memory 32, cache use state information is held.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a central processing unit,
The present invention relates to an information processing system including a storage device and a storage control device having a cache memory, and particularly to an information processing system that manages an area of a cache memory.

[0002]

2. Description of the Related Art The data transfer rate between a cache memory and a disk device is slower than that on the channel side. Therefore, in the technique described in Japanese Patent Application No. 55-157053, a storage control device having a cache memory responds to a write instruction from the central processing device between the central processing device and the cache memory in the storage control device. When the data transfer is completed, a write completion report is issued and a high-speed response is realized to the central processing unit which issued the write instruction. The data transfer process from the cache memory to the disk device is later performed by the storage control device asynchronously with the write instruction from the central processing unit. This control is called write-after control.

The data stored in the cache memory in the storage control device and not transferred to the disk device is referred to as the dirty data. Further, the data stored in the cache memory in the storage control device and matching with the data in the disk device is referred to as clean data. Since this data exists only in the cache memory, it cannot be erased until the transfer to the disk device is completed.

Further, since the data transfer rate between the cache memory and the disk device is slower than that on the channel side, if there are many write instructions from the central processing unit, the cache memory will be reduced by the application of write after control. -There was a possibility that the tide data would fill up.

Japanese Patent Application No. 3-025994 describes a technique for solving this problem. According to the above invention, the storage control device has the amount of data on the cache memory, the amount of write data flowing into the cache memory for each storage device, and the amount of data outflow due to the write-after processing. To monitor. When the data on the cache memory reaches a certain threshold (allowable amount), the inflow amount> the outflow amount of the storage device is limited to the cache memory allocation to the write data, and the storage device Data write priority processing is executed. By this control, the deterioration of the performance of the entire system due to the cache memory being full of data is avoided.

However, in the present invention, the setting of the threshold value is not mentioned. However, in the data input / output processing, there are differences in time zones or processing modes (online processing / batch processing), and moreover, types of data (sequential access data / random access data). The load state (cache hit rate / cache usage rate, etc.) of the cache memory in the storage controller changes depending on Therefore, it is necessary to set an appropriate cache threshold for a read / write request from the central processing unit.

When the threshold value is fixed and the set threshold value is not an appropriate value, the following problems occur. If the set threshold value is lower than the appropriate value, the allocation area for the data on the cache memory becomes smaller in response to the write request from the central processing unit, and the response time due to the occurrence of waiting for the cache memory to become empty. Will be delayed. On the other hand, if the set threshold value is higher than the proper value, the cache read hit rate will decrease.

To solve this problem, Japanese Patent Application No. 3-25994 has means for setting a limit value for the amount of write data in the cache memory according to an instruction from the central processing unit. No mention is made of changing cache thresholds. However, in the case of a storage control device that receives data input / output requests from a plurality of processing devices, it is desirable to set the cache memory allocation limit value (threshold value) by the storage control device.

The means for changing the cache threshold by the storage controller is described in Japanese Patent Laid-Open No. 6-243042. According to this, the storage control device has means for setting a cache memory allocation limit value (threshold value) for each use purpose of the cache and for changing the limit value according to the use state of the cache. By applying the present invention, it is possible to effectively use the cache resource according to the cache load state.

[0010]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the technique described in 2, the setting and changing of the cache memory allocation threshold value are performed in the following procedure. First,
A threshold is set for one of several requests that require cache allocation. After that, measure the information about the cache usage status every unit time,
The cache load information is collected from this information. Then, based on this cache load information, the validity of the set threshold value is determined, and the threshold value is changed if necessary.

Even if the initially set threshold value is a proper value, in the above invention, the cache load state is collected and the validity of the threshold value is determined every unit time. -The overhead for the input / output processing of the computer is large. Therefore, in advance, the time zone of data input / output processing, the processing mode (online processing / batch processing), the type of data (sequential access data / random access data), etc. If it is known, it is desirable to set an appropriate threshold value accordingly. Therefore, it is necessary to appropriately tune the threshold value.

The object of the present invention is to provide a cache memory space.
In order to improve the utilization efficiency of resources, a means for collecting statistical information for tuning an appropriate threshold value and providing it to the user, and a threshold from the user based on the statistical information. It is to provide an apparatus having means for updating a value.

[0013]

In order to achieve the above object, an information processing system according to the present invention comprises a central processing unit, a storage unit for storing data, and a central processing unit and the storage unit. A storage control device having a cache memory for temporarily storing data to be transferred, managing space allocation in the cache memory by control information, and controlling transfer of the data, operation information of the information processing system, and An information processing system comprising: a first means for reading usage information of the cache memory; and a second means for updating the control parameter value to a control parameter value instructed by a user. , Collecting the operation information of the information processing system and the usage information of the cache memory for a certain period by the first means,
Create statistical information and provide the statistical information to the user,
The second means allows the user to instruct the space allocation amount of the cache memory based on the statistical information.

According to the present invention, a central processing unit, a storage unit and a cache memory are provided, and data on the cache memory is assigned a cache space allocation threshold value (hereinafter referred to as a threshold value). In the information processing system consisting of the storage control device controlled by (1), when an inappropriate threshold value is set as described in the related art,
The performance of the entire system may deteriorate. In order to set an appropriate threshold value, the time zone, the processing mode (online / batch processing), and the type of data (see
Statistical information such as the operating mode of the system (such as sequential access data / random access data) and the load state of the cache memory in the storage controller is required. However, if the storage control device itself automatically performs threshold tuning based on these pieces of information, as described in the problem to be solved by the present invention, the data input / output processing is automatically performed. -The head becomes large.

Therefore, the present invention provides the user with the statistical information necessary for tuning the threshold, and the user
An apparatus is provided having means for enabling threshold tuning from the. This makes it possible to set an appropriate threshold value in advance according to the system operation mode.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, in describing the present invention, the configuration and processing flow of the information processing system of this embodiment will be described with reference to FIG. The information processing system according to this embodiment includes a central processing unit 1, a storage control unit 3, a disk unit 2, and a tuning processing unit (SVP) 4. A cache memory 34 in the storage control device 3, and
The control memory 32 is non-volatile. The cache control unit 33 controls cache allocation. The control memory 32 is a memory for storing control information of the storage control device 3. The information stored in the control memory 32 will be described later as needed. The channel control unit 31 has an interface function between the central processing unit 1 and the storage control unit 3, and accepts and executes a data input / output request of the disk device 2 issued by the central processing unit 1. . The drive control unit 35 has an interface function between the disk device 2 and the storage control device 3, and
And the data transfer between the storage controller 3 and the storage controller 3. SVP
Reference numeral 4 is connected to the storage control device 3. The SVP interface unit 36 has an interface function between the storage control device 3 and the SVP 4. The interface unit 43 with the storage control device has an interface function between the storage control device 3 and the SVP 4. The SVP 4 has a threshold tuning control unit 41, which is a feature of the present invention, and a non-volatile threshold control memory 42. The threshold tuning control unit 41 performs cache load statistical information generation, threshold update information generation, cache load statistical information output, and threshold setting. Details of these will be described later as necessary. The threshold control memory 42 holds the cache load statistical information necessary for threshold tuning and the threshold update information. For more information,
It will be described later as necessary.

Each of the cache control unit 33, the channel control unit 31, the drive control unit 35, and the SVP interface unit 36 described above is a program in the microprocessor of the storage control device 3. Further, the threshold tuning control unit 41 and the interface unit 43 with the storage control device are programs in the microprocessor of the SVP4.

Next, the central processing unit 1 to the disk unit 2
An outline of the data flow when a data read request is issued will be described. Upon receiving the request, the channel control unit 31 first refers to the control memory 32 and determines whether the requested data exists in the cache memory 34 (hit) or does not exist (miss). This is called a hit / miss decision. If the result of determination is a hit, the data from the cache memory 34 is sent to the central processing unit 1.
Transfer to If it is a miss, the data is transferred from the disk device 2 to the cache memory 34 and then from the cache memory 34 to the central processing unit 2. The data is transferred to the central processing unit 1 and the read request ends.

Next, the central processing unit 1 to the disk unit 2
Data when a write request is issued to the data in the
An outline of the data flow will be explained. Upon receiving the request, the channel control unit 31 refers to the control memory 32 and makes a hit / miss determination as in the case of the read request. If it is a hit, the update data is written to the data in the cache memory 34. In the case of a miss, first, the update target data is transferred from the disk device 2 to the cache memory 34, and then the update data is written. In either case of hit / miss, the write request is terminated when the update data is written in the cache memory 34. At this time, the data that has been written to the cache memory 34 but has not been transferred to the disk device 2 is called dirty data (write pending data). Cache memory 3
The data on the disk 4 is later transferred to the disk device 2 by the drive controller 35. This is called write-after control.

Next, the structure of the cache memory 34 will be described. The data on the cache memory 34 is managed in units called slots as shown in FIG. This slot corresponds to a data management unit for one track on the disk device 2 and includes a plurality of records. A slot control block (hereinafter referred to as SLC) is used to manage each slot.
(Abbreviated as B) is used. This SLCB is a control memory 32
Stored in. As shown in FIG. 3, the SLCB includes a queue type, a forward pointer, a backward pointer, and slot management information. Next, management of a plurality of SLCBs in the control memory 32 will be described. The SLCB has a forward pointer and a backward pointer.
Is managed in the control memory 32 using this pointer. There are three types of queues: empty SLCB queue, reusable SLCB queue, and write pending SLCB queue. The empty SLCB queue is a queue that connects SLCBs that manage cache slots that are not assigned to data in the disk device 2. The reusable SLCB queue holds data in cache slots, but if necessary, an SLCB that manages cache slots that can be used to allocate new data. It is a connecting kyu. The write pending SLCB queue is only written to the cache memory 43, and the disk device 2
Is a queue for connecting the SLCB that manages the cache slot holding the write-pending data that has not been reflected.

Next, the control memory 32 will be described.
The cache usage status information is held in the control memory 32. This information includes empty SLC as shown in FIG.
There are B queues, reusable SLCB queues, write pending SLCB queues and cache management tables. The cache management table 324 has the contents shown in FIG. It should be noted that other than the control information that characterizes the present invention, they are not shown. The cache control unit 33 writes the cache use information to the cache management table 324 every time the cache memory 34 is used.

Further, the cache control unit 33, in order to prevent the cache from being occupied by the write pending data, allocates the cache space with the threshold value of the write pending data amount stored in the control memory 32. If it exceeds the limit, the cache slot allocation for the write request is limited. This control is called cache load control.

Next, the table structure in the threshold control memory 42 will be described. The threshold control memory 42 has a cache load statistical information table 405 and a threshold update information table 406. FIG. 6 shows the contents of the cache load statistical information table 405. Each history information is generated by the threshold tuning control unit 41 by referring to information on the cache management information table 324 in the control memory 32 in the storage control device 3 for each unit time. Is. The threshold tuning control unit 41 provides the history information to the outside if specified. Next, FIG. 7 shows the contents of the threshold value update information table 406. The tuning control unit 41 collects information necessary for tuning the threshold value and sets the threshold value based on the information on the threshold value update information table 406. Details of the threshold update information table 406 will be described later.

Next, in this information processing system, FIG. 8 will be used for the flow of processing for collecting statistical information and providing information necessary for performing threshold tuning, which is a feature of the present invention. Explain.

First, the start time and the end time for acquiring the cache load statistical information are set from the SVP 4.
Here, the collection period of statistical information may be used instead of the end time. The threshold tuning control unit 41 of the SVP4, at the start time, cache management table for each unit time.
Collect information (3240-3250) on Bull 324,
Each history information (4050 to 4054) is created and stored in the cache load statistical information table 405 in the threshold control memory 42. The unit time for collecting information may be set in advance or may be set externally. This is performed until the end time or the expiration of the statistical information collection period. The SVP 4 holds the cache load statistical information in the threshold control memory 42 until an instruction to provide the collected statistical information is given from the outside. Then, when there is an instruction to provide the cache load statistical information, the statistical information is provided to the outside. As a method of providing, the screen display on the SVP4 may be used, or the statistical information may be printed by connecting a printer to the SVP4. In the above process, the threshold tuning mode for collecting the above statistical information and checking whether the set threshold is appropriate only when the threshold is tuned. For this reason, there is a threshold monitoring mode that collects cache load statistical information and a normal mode that does not collect statistical information only when the number of write pending SLCBs exceeds a threshold value. The mode may be selected from the SVP4. This mode switching can be performed by the tuning mode setting flag on the threshold update information table shown in FIG.

Next, a process flow of setting a target threshold value from the outside and updating the current threshold value to the target value will be described with reference to FIG. First, a target threshold value is set. Then, the processing time T required to update the threshold value is set from the current threshold value to the target threshold value. Here, the processing time T may be set in advance or may be input from the outside. Then, the update amount Δx of the threshold value per unit time is calculated using the calculation formula of FIG. 10. While the current threshold value does not reach the target threshold value at 940 in the flow chart, the current threshold value is updated by 950 for each unit time at 950 while the current threshold value is calculated. When the current threshold value reaches the target threshold value, the process ends.

The threshold value may be updated as shown in FIG. First, a target threshold value is set. Next, the flow
At 1120 in the chart, the update amount Δx of the threshold value per unit time is set from the outside. Here, this Δx may be set in advance. At 1130 in the flow chart, 114 in the flow chart are set while the current threshold value does not reach the target threshold value.
At 0, the current threshold value is updated by Δx every unit time. When the current threshold value reaches the target threshold value, the process ends.

The threshold value may be updated as shown in FIG. First, a target threshold value is set. Next, the update amount Δx of the threshold value per unit time is set from the outside. Here, this Δx may be set in advance. At 1230 in the flow chart, if the current threshold value is not the target threshold value, 124 in the flow chart.
At 0, the current threshold value is updated by the above Δx. After that, at 1250 in the flow chart, the cache management table 3
Collect the number of light-pending SLCBs on 24, and use 1260 in the flow chart for this light-pending SL.
The size of the CB number and the current threshold value are compared. As a result, if the number of write pending SLCBs is larger than the current threshold value, the process is returned to 1250 in the flow chart, and 1260 in the flow chart is compared again.
Thus, by the cache load control by the cache control unit 33, the processes of 1250 and 1260 in the flow chart are repeated until the number of write pending SLCBs becomes equal to or less than the current threshold value. Light pending S
If the number of LCBs falls below the current threshold, the flow chart
If the current threshold value has not reached the target threshold value, the current threshold value is updated by Δx. And again, 1250, 1 in the flow chart
The process of 260 is performed. In this way, when the threshold value reaches the target threshold value, the processing ends.

The updating of the threshold value is performed by referring to FIG.
The methods of FIGS. 11 and 12 may be used together.

Further, the threshold value updating may be performed based on the threshold value updating information for a certain period as shown in FIG. First, the start time T1 and the end time Tn of the threshold value setting are input. Here, instead of the end time, the threshold updating period may be used. Then, within the set period, set the threshold value for each time as shown in FIG.
Create threshold update information. Then, the flow of FIG.
At 1430 in the chart, the processing is started when the threshold update start time comes. Based on the created threshold update information, when the threshold update time comes, the threshold at that time is updated to the target threshold at that time. FIG.
For the update of the threshold value at 1450 in the flowchart of FIG. 4, the threshold value at that time may be directly changed to the target threshold value set at each time. The threshold value may be updated stepwise to the target threshold value by using the method shown in FIGS. Then, when the threshold value update period is completed or the end time Tn is reached, the threshold value update is ended.

Further, as shown in FIG. 15, the threshold value update information created in FIG. 13 may be patterned and repeated within a fixed period to set the threshold value. The flow of this processing will be described with reference to the flowchart of FIG.
First, the unit period (T1, T of the threshold update pattern)
n) is set (see FIG. 15). Then, the period (S1, Sn) for repeating this threshold value updating unit is set (see FIG. 15). After that, 16 in the flowchart of FIG.
At 30, the threshold update information within the unit period (T1 to Tn) is created (see the threshold update pattern of FIG. 15). When the start date and time S1 of the threshold value update period is reached, the process is started. First, at the start time of the threshold value update unit period, the threshold value is updated based on the threshold value update information set as shown in FIG. When the unit period of the threshold update pattern has expired or the end time has come,
In the processing of 1680 during the flow chart, it is determined whether the threshold update period has expired or the end date / time Sn, and if it is within the threshold update period, the process proceeds to 1650. In this way, the updating of the patterned threshold value in the unit periods T1 to Tn is repeated during the periods S1 to Sn.

As described above, the threshold value updating process described with reference to FIGS. 9 to 16 can be freely selected by the threshold value updating mode setting flag on the threshold value updating information table 406.
It is also possible to combine several threshold updating processes described above.

Further, during the updating of the threshold values described with reference to FIGS. 9 to 16, even if the processing of collecting the cache load statistical information necessary for the threshold tuning as described with reference to FIG. 8 is performed in parallel. good. Then, the threshold value may be set based on the statistical information.

As a method of setting the threshold value based on the statistical information, for example, there are the following methods.

(1) The present value threshold value is updated to the designated target threshold value at the time designated by the user. As described in the related art, when the threshold value is fixed, the performance of the entire system may be deteriorated when the load state of the cache memory in the storage controller changes due to the change of the operating state of the system. Therefore, by grasping the operation form of the system for a certain period from the statistical information and enabling the setting of the update pattern of the threshold value for the certain period according to the operation of the system based on it, the cache memory To make effective use of.

(2) The threshold value is updated stepwise from the current value to the target value set by the user. If the target value of the threshold value is lower than the current value, if the threshold value is suddenly changed to the target value, the allocated area for the date data on the cache memory decreases and the load on the cache becomes high. Delay in response time occurs due to waiting for free memory. Therefore, in the present invention, the threshold value is updated by gradually changing the threshold value from the current value to the target value while suppressing the high load state of the cache.

As in the embodiment of the present invention, the load information of the cache is provided to the outside as statistical information and the threshold value is tuned from the outside, so that the operating form of the system can be grasped and the system can be operated. It is possible to provide a method and a device for making effective use of the cache space by presetting an appropriate threshold value.

[0039]

According to the disk cache tuning processing device of the present invention, the operating information of the information processing system and the cache load information are provided to the user as statistical information, and the user selects the threshold value tuning information. -It is possible to perform training. Therefore, according to the operating mode of the system,
Since an appropriate threshold value can be set in advance, it has an effect of improving the space utilization rate of the cache memory.

[Brief description of drawings]

FIG. 1 shows a block diagram of an information processing system according to an embodiment of the present invention.

FIG. 2 shows a configuration of a cache memory.

FIG. 3 shows an explanatory diagram of a slot control block (SLCB).

FIG. 4 shows an explanatory diagram of information in a control memory.

FIG. 5 shows an explanatory diagram of a cache management table.

FIG. 6 shows an explanatory diagram of a cache load statistical information table.

FIG. 7 shows an explanatory diagram of a threshold update information table.

FIG. 8 shows a processing flow for collecting cache load statistical information when the threshold tuning mode is in the tuning mode.

FIG. 9 shows a processing flow of threshold value updating processing example 1.

FIG. 10 shows a calculation formula for calculating an update amount per unit time.

FIG. 11 is a process flow chart of threshold value updating process example 2;
Is shown.

FIG. 12 is a process flow chart of threshold value updating process example 3;
Is shown.

FIG. 13 shows an explanatory diagram of threshold value update information example 1.

FIG. 14 shows a processing flow of threshold value updating processing example 4 for updating a threshold value based on threshold value updating information example 1.

FIG. 15 is a diagram showing threshold value update information example 2 in which the threshold value is patterned and the threshold value is updated.

FIG. 16 shows a processing flow of threshold value updating processing example 5 in which threshold value updating information is patterned to update the threshold value.

[Explanation of symbols]

1 Central processing unit 2 Disk unit
3 Storage Control Device 32 Control Memory 33 Cache Control Unit
34 cache memory 4 tuning processor (SVP) 41 threshold tuning control unit 42 threshold control memory

Claims (3)

[Claims] 1. A central processing unit, a storage device for storing data, and a cache memory for temporarily storing data transferred between the central processing unit and the storage device. A storage controller that manages space allocation by control information and controls the transfer of the data, a first means for reading operating information of the information processing system and usage information of the cache memory, and the control parameter value. A second means for updating the control parameter value instructed by the user, wherein the operation information of the information processing system and the cache by the first means. By collecting the usage information of the memory for a certain period of time, creating statistical information, providing the statistical information to the user, and by the second means,
An information processing system wherein the user can instruct a space allocation amount of the cache memory based on the statistical information. 2. The information processing system according to claim 1, further comprising means for updating the control parameter value at a time designated by the user. . 3. The information processing system according to claim 1, further comprising means for updating the control parameter value stepwise.