JPS61136146A - Main memory control method for electronic computer system - Google Patents

Abstract

PURPOSE:To decrease the capacity of a main memory which is occupied by a bit map by producing the bit map with use of an optional part of a page number. CONSTITUTION:A degeneration bit map 7 of a single unit is prepared in response to plural numbers of page 2 stored in a secondary storage device 1. The map 7 is set at '1' when either one or both of two pieces of page 2 are stored in a page processing buffer 4. Otherwise the map 7 is set at '0'. Thus it is known unconditionally that no corresponding page 2 exists on the buffer 4 in case the corresponding map 7 is set at '0'. At the same time, the page processing buffers 4 are all checked when the map 7 is set at '''1'. Thus it is known with the 1/2 probability at most that no corresponding page 2 exists.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is a main culprit +1 in electronic computer systems! The present invention relates to a main memory management method for transferring data between a device and a secondary storage device at high speed.

[Conventional technology]

Figure 2 shows the method conventionally used to confirm the existence or nonexistence of a page. Page (2) must be processed by the computer system in the page processing buffer (4) on the main memory (3).
). Generally, the number of page processing buffers (4) is much smaller than the number of pages (2), so only a portion of page (2) can be stored in the page processing buffer (4). Therefore, when a computer system processes a specific page (2), it checks whether it exists in the page processing buffer (4) in the main memory (3), and if it does not exist in the secondary memory ( 1
) is transferred to the page processing bar P (4) on the main storage (3). Bitmap (5) or LRU chain (
8) is used. Bitmap (5) is page (2)
If the specific page (2) exists on the page processing buffer (0, then the value is "1", otherwise the value is O". LRU chain (8)
) corresponds to each page processing buffer (4), and stores the number of the page (2) existing on the page processing buffer (4).

Next, regarding the operation of the above configuration, see I' map (5)
We will explain the case using the LRU chain (θ) and the case using the LRU chain (θ). First, when using the be/) map (5), when checking whether a specific page (2) exists in the page processing bus (4), the computer system Check the value of the bitmap (5) corresponding to the number, and if it is "1", it is determined that it exists on the page processing buffer (4), and
o”, the page processing buffer (4) occupied by another page (2) is released, and the page to be processed (2) is released.
) is transferred and stored in the page processing/(sofa (4)), and the values of the bitmaps (5) corresponding to the old and new pages (2) occupying the page processing buffer (4) are swapped.

Next, when using the LRU chain (El), the computer system examines the LRU chain (6) and determines whether there is a number corresponding to the specific page (2) to be processed. New page (2) on page processing buffer (4)
If one of them is stored, the page processing buffer (
The number corresponding to page (2) that occupied 4) is LR
The number of page (2) deleted from the U chain (8) and newly stored in the page processing buffer (4) is L.
Registered in RU chain (8).

[Problems to be Solved by the Invention] Since the confirmation of page existence in the conventional main memory management method is performed as described above, when the capacity of the secondary storage device (1) is extremely large, the bit map (5 ) Just the main culprit! ! There were problems such as (3) occupying most of the storage capacity and searching for LRU chain (6) requiring a large amount of processing time.

This invention was made in order to solve the problems of the conventional ones as described above.The main storage capacity occupied by the bit map is small, and the required pages can be stored in the main storage. It is an object of the present invention to provide a main memory management method in a computer system that can quickly determine whether or not a file already exists on the computer system.

[Eight Means for Solving the Problem] The main memory management method in the computer system according to the present invention is a degenerate bit method that allocates one bit of the main memory to a plurality of pages on the secondary memory. It has a map.

[Operation] When preparing a degenerate beat-two map that allocates 1 bit in the main memory to, for example, two consecutive pages in the secondary storage A, one of the two pages, Or, since both are page processing, if the value of the degenerate bitmap is "o", it is known that there is no corresponding page on the page processing buffer; on the other hand, if the value of the degenerate bitmap is In the case of "t",
This means that one or both of the two pages are stored, so by checking all of the page processing buffers, the station will know with probability that there is no corresponding page.

[Example] In Fig. 1, (1) is a secondary storage device, (2) is a page, (3) is a main storage device, and (4) is a page processing unit (sofa). They have the same configuration. (7) is a degenerate bit map used in the present invention, and one
A degenerate bit map of units is provided.

By configuring as above, even page (2)
Even if the number of page processing buffers (4) is far greater than the number of page processing buffers (4), there is only a small amount of main culprit memory! ! By simply occupying page (2), it is possible to quickly determine whether a specific page (2) exists on page buffer (4). That is, for example, the first
As shown in the figure, 1 corresponds to the two contact pages (2).
In the case where two degenerate page maps (7) are prepared, one or both of the two pages (2) is used as a page processing buffer. By doing this, if the value of the corresponding degenerate bitmap (r7) is 0'', the corresponding page (2) is unconditionally transferred to the page processing buffer (4).
If you know that it is not above, and if the value is 1''' 7
In this case, all 0s in the page processing buffer (0) will be checked, and it will become clear at most that the corresponding page (2) does not exist. One degenerate bit map (7) was made to correspond to the
Since there is generally a bias in the order in which pages (2) are processed, it is possible to change the mapping according to the characteristics6.
For example, one degenerate bit per 100 pages (2).
The maps (7) may be made to correspond, or the pages (2) whose remainders are the same when divided by a certain numerical value may be made to correspond to the same degenerate bit map (7).

[Effect of the invention 1 As described above, according to the present invention, a bit map is created using an arbitrary part of the page number, so the main memory capacity of the main memory device occupied for the bit number map is reduced. Only a small amount is required, and it is possible to quickly determine whether the referenced page already exists on the page processing buffer of the main storage device, unless the page is referenced in a completely random order.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a main memory management method in a computer system using a degenerate bit map according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the same conventional main memory management method. In Figure 0, (1) is the secondary storage device, (2) is the page, (3) is the main storage device, (4) is the page processing buffer, (5) is the bit number map, and (7) is the degenerate page. It's a map. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a main memory management method in a computer system that transfers pages from a secondary storage device to a page processing buffer of a main storage device, one bit on the main storage device is allocated to a plurality of pages on the secondary storage device. Degenerate bit
A main memory management method in a computer system characterized by providing a map.