JPH09244958A - Paging method and system therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency of paging by deciding a page in use to perform page-out based on the regular pattern of the order of the page to be used when a page fault is generated. SOLUTION: When the execution of a program is started, the number of the page to be accessed is registered in an access page history storage part 5 and registered in an LRU(least recently used) management storage part 4 as a priority order '1'. Thereafter, a similar processing 15 performed every time the page to be accessed is switched, and when the accessed page is accessed again after several pages, a history during the time is extracted from the access page history storage part 5 and registered in an access page pattern storage part 6 as pattern data. When the page fault is generated, the pattern data for the page to be accessed are read and a paging processing is performed with the page not present in the pattern as a page-out object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a virtual memory system, and more particularly to a paging control method and system.

[0002]

2. Description of the Related Art In the conventional paging system, the LRU method (Least Receive) is mainly used as a page selection method for page-out in order to reduce the number of page faults.
The ntly Used method) was adopted. In this LRU method, a page that has not been used in the main memory for a certain period of time is selected and the page out is performed based on the assumption that the page will not be used in the near future.

Further, as a publicly known technique, there is Sho 59-548.
The "group page management processing method" of 0 makes the page-in / page-out processing by grouping a plurality of continuous arbitrary pages and grouping the page groups to improve the paging efficiency and speed. It is trying to make it. 62-131
The “paging control method” 353 aims at improving the efficiency of paging by providing a plurality of LRU reference bits to control the state of page access. 1-24
165 “Paging method with priority specified”
Provides a priority that can be specified by the user for each page attribute, and performs page-in / page-out processing according to the priority to enable fine page control. The "page number variable type on-demand paging method" of flat 2-238535 is based on dynamically determining the number of page-in / page-out pages based on the history of page access data within a fixed time. It is intended to improve the efficiency of paging.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the law, the page-out page is determined to be a page that has not been used for a certain period of time, so a page fault frequently occurs in a program that naturally uses an unused page for a certain period of time. However, there was a problem that the execution speed became slow.

Further, in the above-mentioned publicly known technical example, in the case of Sho 59
The "group / page management processing method" of -5480 causes the above problems depending on the grouping method as in the LRU method. The "paging control method" of Sho 62-131353 and the "on-demand paging method of variable number of pages" of Hei 2-238535 are improved methods of the conventional LRU method, and the above problems still remain. The “paging method with priority specified” of Hira 1-24165 differs from the present invention in that the page-out target is delegated to the user.
Similarly, the above problem may occur.

An object of the present invention is to eliminate the drawback of page-out targeting a page which is not used for a certain period of time but is immediately required in the conventional LRU method at the time of page fault.
It is an object of the present invention to provide a paging method and its method that can reduce the number of page faults and improve the efficiency of paging.

[0007]

In order to solve the above-mentioned problems, a paging method of the present invention is a paging method in a virtual memory system using a paging method, and a paging method to access when one program is executed. A step of storing a sequence of pages, a step of storing a regular pattern of the stored page as pattern data, and a page fault when a page fault occurs.
There is a step of selecting a page to be paged out based on the pattern data for the page to be paged in.

Further, the paging method of the present invention includes a paging information processing section for performing a paging process, an execution page storage section for storing a program for a page that can be accessed when executing a program, and all unexecuted pages. In the paging method in the virtual storage system using the paging method having the unexecuted page storage unit that stores the executed page and the LRU management storage unit, the order of pages to be accessed when one program is executed is the access page history data. And a step of storing a regular pattern in the access page history data as access page pattern data, based on the access page pattern data for a page to be paged in when a page fault occurs. To select the page to be paged out. With a flop.

Further, in the step of storing the regular pattern in the access page history as access page pattern data, when the page to be accessed is changed when the program is executed, the number of the executed page is accessed. Step to register as page history data,
The page number of the access page history data is registered as the page number corresponding to the priority 1 in the LRU management storage unit, and the priority of all pages already registered in the LRU management storage unit is set to 1. Step by step to delete the record of the page with the lowest priority, and the history data up to the place where the page was executed before that page is accessed. Reading from the page history data, and if the length of the read history is equal to or more than the preset number of pages, registering the history of the number of pages-1 as pattern data, and the number of pages is less than the number of pages. If the number of pages is 1 or more, register the pattern data as it is, and if the number of pages is 0, do not register the pattern data. To.

Further, when the page fault occurs, the step of selecting the page to be paged out based on the regular pattern for the page to be paged in is the step of selecting a page from the unexecuted page storage section. When there is no free area in the execution page storage unit 2 during the in process, there is pattern data for the corresponding page, and there is a page not included in the pattern data in the execution page storage unit. Page is targeted for page-out, the page-out processing step is performed, and if there is no pattern data for the page, the page with the lowest priority in the LRU management storage section is displayed. If there is no page that is not included in the pattern data in the execution page storage unit as one page-out target, and if there is no page in the execution page storage unit, L
There is a step of performing a page-out process with a page having the lowest priority in the RU management storage unit as a page-out target.

Further, the paging system of the present invention includes a paging information processing section for performing a paging process, an execution page storage section for storing a page of a program that can be accessed when executing a program, and all unexecuted pages. In the paging system in the virtual storage system using the paging system having the unexecuted page storage unit for storing the executed page and the LRU management storage unit, the order of pages accessed when one program is executed is the access page history data. And a means for storing a regular pattern in the access page history data as access page pattern data, based on the access page pattern data for the page to be paged in when a page fault occurs. Has a means for selecting a page to be paged out.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. The paging system of the present invention is executed by a paging information processing unit 1 for controlling paging processing, an execution page storage unit 2 for storing a page of a program that can be accessed when executing the program. An unexecuted page storage unit 3 that stores all pages of a program and a page that is not used for a certain period when an attempt is made to use a page that is not in the executed page storage unit 2 (a page fault has occurred).
LRU (Least Recent Us) for performing a page-out process of saving the page from the execution page storage unit 2.
ed) method, a page to be paged out can be stored in the execution page memory 2 by prioritizing the number of pages and managed by the LRU management memory 4 and the page to be accessed. An access page history storage unit 5 for storing history,
It has an access page pattern storage unit 6 for storing a page pattern to be accessed.

Next, referring to FIGS. 1, 2 and 3,
The operation of the present embodiment will be described. Here, it is assumed that the number of pages that can be stored in the execution page storage unit 2 is three.

FIG. 2 is a flow chart showing an interrupt process when switching pages. Pages that can be stored in the execution page storage unit 2
In a virtual memory system with multiple pages, when the page to be accessed changes when the program is executed,
The number of the executed page is registered in the access page history storage section 5 (A1), and the page number is registered in the page number section corresponding to the priority level 1 in the LRU management storage section 4 (A2). ). At that time, the priority of all pages already registered in the LRU management storage unit 4 is lowered by one, and the record of the page having the lowest priority is deleted. Next, the history of the executed page up to the point where the page was executed is read from the access page history storage unit (A3).

When the length (number of pages) of the read history is 3 pages or more that can be stored in the execution page storage unit 2 at the maximum (A4), the history of the maximum number of pages-1 = 2 is used as pattern data to access the page pattern. Register in the storage unit 6 (A6). When the number of pages is less than the maximum number of pages 3 (A4), if the number of pages is 1 or more (A5), it is registered as it is in the access page pattern storage unit 6 as pattern data (A7). If the number of pages is 0 (that is, there is no history) (A5), it is not registered in the access page pattern storage unit 6.

FIG. 3 is a flow chart showing the interrupt processing at the time of page fault. Attempt to access a page that is not in the execution page storage unit 2 (a page fault has occurred)
In this case, the page needs to be loaded (page-in) from the unexecuted page storage unit 3, but if there is no free area in the executed page storage unit 2 (Bl), the pattern data for the page is stored. Is the access page pattern storage unit 6
If there is a page not included in the pattern data in the execution page storage unit 2 (B3), the page is targeted for page out (B4), and the page out process is performed ( B6). When the pattern data for the corresponding page does not exist in the access page pattern storage unit 6 (B
2) or if there is no page not included in the pattern data in the execution page storage unit 2 (B3), the page with the lowest priority in the LRU management storage unit 4 is targeted for page out (B5). , Page-out processing is performed (B6).

[0018]

As described above, according to the present invention,
The pattern data of the access page history of the executed program is stored, and the page to be paged out is selected from the pattern data including the page to be paged in at the time of a page fault, and the page out process is performed.
The U method has the effects of eliminating the drawback that the page-out target is a page that has not been used for a certain period of time but is needed immediately, the number of page faults is reduced, and the efficiency of paging is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the configuration of the present invention.

FIG. 2 is a flowchart showing an interrupt process at the time of page switching according to an embodiment of the present invention.

FIG. 3 is a flowchart showing interrupt processing at the time of a page fault in one embodiment of the present invention.

[Explanation of symbols]

 1 paging information processing unit 2 executed page storage unit 3 unexecuted page storage unit 4 LRU management storage unit 5 access page history storage unit 6 access page pattern storage unit

Claims (6)

[Claims] 1. A paging method in a virtual storage system using a paging method, wherein a step of storing the order of pages to be accessed when one program is executed, and a regular pattern of the stored pages are stored. And a step of storing as pattern data and a step of selecting a page to be paged out based on the pattern data for a page to be paged in when a page fault occurs. Zing method. 2. A paging information processing section for performing a paging process, an execution page storage section for storing a program for a page that can be accessed when executing a program, and an unexecuted page storage for storing all unexecuted pages. Department and LR
In a paging method in a virtual storage system using a paging method having a U management storage unit, a step of storing the order of pages accessed when one program is executed as access page history data; Storing a regular pattern of the access page pattern data as access page pattern data, and a page based on the access page pattern data for the page to be paged in when a page fault occurs.
A paging method comprising the step of selecting a page to be subject to a page out. 3. The step of storing the regular pattern in the access page history as access page pattern data, when the page to be accessed is changed when the program is executed, the number of the executed page is accessed. Registering as page history data, and registering the page number of the access page history data as a page number corresponding to priority 1 in the LRU management storage unit, and all already registered in the LRU management storage unit. Lowering the priority of each page by 1 and deleting the record of the page with the lowest priority, and the page that was executed before that page was executed. The history data up to the specified location is read from the access page history data, and the length of the history read is greater than or equal to a preset number of pages. In the case, the step of registering the history of the page number -1 as pattern data; and in the case of the page number being less than the page number, if the page number is 1 or more, the step of registering the pattern data as it is, The paging method according to claim 2, further comprising a step of not registering as pattern data when the number of pages is 0. 4. When the page fault occurs, the step of selecting a page to be paged out based on the regular pattern for the page to be paged in is a page-in from the unexecuted page storage section. If there is no free area in the execution page storage unit 2 during processing, there is pattern data for the corresponding page, and if there is a page not included in the pattern data in the execution page storage unit. Is the page-out target for the page, and the step to perform the page-out process. If there is no pattern data for the page,
If the page with the lowest priority in the LRU management storage unit is targeted for page-out processing, and if there is no page not included in the pattern data in the execution page storage unit, the LRU management storage unit 3. The paging method according to claim 2, further comprising a step of performing a page-out process with a page having the lowest priority order of pages as a page-out target. 5. A paging information processing unit for performing paging processing, an execution page storage unit for storing a preset number of pages, an unexecution page storage unit for storing all unexecuted pages, and an LRU management storage unit. In a paging method in a virtual memory system using the paging method, a means for storing the order of pages accessed when one program is executed as access page history data, and a regular pattern in the access page history data Means for storing as access page pattern data, and a page based on the access page pattern data for the page to be paged in when a page fault occurs.
A paging method characterized by having means for selecting a page to be targeted for jiout. 6. A paging information processing section for performing a paging process, an execution page storage section for storing a page of a program that can be accessed when executing a program, and an unexecuted page storage for storing all unexecuted pages. Department and LR
In a paging system in a virtual storage system using a paging system having a U management storage unit, an access page history storage unit that stores, as history data, an order of pages to be accessed when one program is executed; An access page pattern storage unit that stores a regular pattern in the data as access page pattern data, and a page to be paged out from the access page pattern storage unit for a page to be paged in when a page fault occurs. A paging method characterized by selecting one page.