JPS62189543A - Address conversion system - Google Patents

Abstract

PURPOSE:To obtain a flexible address conversion system by providing a shared address conversion table of an area shared between respective viertual spaces in corresponding to plural entries of a conversion table, and a means detecting the shared address conversion table from the respective virtual spaces. CONSTITUTION:In case virtual spaces share some page, an identification name 71 is designated and taken for a key, and a shared address conversion table directory CPD 70 is searched. Then the coincident entry is found, and information on the address 74 in a target shared address conversion table CPGT 150 is obtained. Based on the information each entry 142 in a page conversion table 140 can be generated. Thus the shared page does not need to have the same page address in the respective virtual spaces. Moreover table capacity corresponding to the shared amount suffices in terms of the shared page conversion table, and a small shared table can realize the page sharing control at the high degree of freedom.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a computer that employs a virtual memory system, and particularly to an address conversion system suitable for sharing memory between jobs running on the computer.

[Conventional technology]

In the conventional method, as described in Japanese Patent Application Laid-Open No. 56-65380, the address translation table is only a page table in order to have flexibility in the unit of sharing between each virtual space, and indirect addressing is introduced. Achieves page-by-page sharing.

[Problem that the invention seeks to solve]

However, the page address on each virtual space configuration is used as the index of the common page address table used in indirect addressing, and the common page address table requires capacity not only for the common pages but also for the total decrement of the virtual space. . Furthermore, virtual space tends to expand, and conventional methods require a huge amount of storage capacity for the common page address table. In addition, to share an area, the address in each virtual space is converted into a real address and the result is a result of pointing to the same real address, but in the conventional method, the virtual address in each virtual space must also be the same. Must be.

In such a system, it is not possible to share any location in the virtual space.

The purpose of the present invention is to eliminate various restrictions that occur when sharing areas between virtual spaces, suppress the increase in shared page conversion tables, and provide highly flexible addresses that can share any page in each virtual space. The purpose is to provide a conversion method.

[Means for solving problems]

In the address translation method of the present invention, when a request for a common page is made for the first time, a common page translation table for only the requested amount is dynamically secured, and the page translation table entry in each virtual space is used indirectly. An addressing scheme is used to point to a corresponding entry in the shared page translation table.

Further, a directory table for managing all the shared page conversion tables on the computer is provided, and the shared page conversion table management information (size, identification name, address, etc.) is stored in the directory table.

[Operation] When a sharing request for a common page registered in the directory table is made from each virtual space, the virtual space first allocates a virtual area in its own virtual space, that is, creates an entry in a page conversion table. . In the entry of the page conversion table, an entry address of the common page conversion table that includes the target shared page is obtained from the directory table, and the address is set.

Thereafter, when converting a virtual address in each virtual space to a real address, check the shared bit in the page translation table in each virtual space, and perform indirect addressing via the common page translation table. Determine whether it is a method or not.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 shows an outline of page sharing in this embodiment. In FIG. 1, pages All and B21 in the virtual space AIO and the virtual space B20 are transferred to the same address in the real memory 30 through an address conversion 100 adapted to the present invention.
By converting to real page 31, page All and page B21 are shared.

Next, address translation 100 will be explained with reference to FIGS. 2 to 5.

FIG. 2 shows an outline of the address translation table in this embodiment. In this embodiment, the virtual space is divided into logical unit segments, and the segments are further divided into page units.
Each of these is managed by a segment table 5GT120 and a page table PGT140, and each entry in the 5GT120 is composed of a pointer to the page table PGT140 that constitutes the segment.
Depending on the content of the shared bit 144, each of the 40 entries 141 and 142 may directly point to the real page 31 on the real memory 30, or the shared address translation table NCPGT 150
In some cases, the page 31 on the real memory 3o may be pointed to by indirect addressing via.

3 and 4 show the entry formats 141 and 142 of the page table PGT140. The shared bit 144 on the entry is set to 1 for a shared page in this embodiment at the time of virtual memory allocation. Set to 0 for non-shared pages. Further, when the shared address translation table CPGT 150 is created, the identification name 7 of the shared address translation table CPGTI 50 is written on the shared address translation table directory CPD 70.
1° size 72. The number of users 73 and address 74 are set. On the other hand, when sharing a page from another virtual space, specify the identification name 71, search the shared address conversion tape directory CPD 70 using the identification name 71 as a key, find a matching entry, and use the desired shared page. Address 7 of address conversion table CPGT50
4 etc. information, and based on this, create page conversion table 14.
Each entry 142 on 0 can be created.

Next, how the address translation operation is performed will be explained using the various tables described above with reference to FIG. FIG. 5 is a block diagram showing the address translation method of the present invention. The contents of the virtual address 60 corresponding to the virtual space are segment index 5G61. It consists of a page index 62 and a displacement DP 63 indicating displacement within the page. The conversion of the virtual address 60 is performed by first converting the start address of the segment table 5GT 120 on the control register 50 and the virtual address 6
Add 5G61 on 0 using ALUIIO (as shown in the figure, multiply each position by a predetermined constant and then add; the same applies to the following additions) to obtain the target segment table entry 120. The start address of the page table PGT140 on the segment table entry 120 and the PG62 on the virtual address are stored in the ALU 13.
0 is added to obtain the page table entry 141 on the PGT 140. The page table entry 141
contains 32 bits of information (expressed as the 0th bit, 1st bit, etc. from the left), and the 0th bit is the shared bit 1.
44 becomes a control signal for the selector 160, and when the shared bit 144 is 0, the 1st to 19th bits directly indicate the real page address.
If 4 is 1, the shared page table 150 (Figure 2)
Points to entry CPGEI 51 in.

The CPGE 151 and the page table entry 141 (shared bits 1st to 19th bits at 0) are input to the selector 160, and under the control of the shared bit 144, the upper address RPAI 71 of the real address 170 is
becomes. At this time, the real address 170. Lower address B
In A172, the displacement DP63 in the virtual address becomes the real address as it is. According to this embodiment, the shared page table 150 only needs to have a capacity of 4 bytes per common page, and furthermore, the address of the common page in each virtual space can be set at any position, allowing for a high degree of freedom in page units. Sharing can be achieved. [Effects of the Invention] According to the present invention, it is not necessary for a shared page to have the same page address in each virtual space, and furthermore, the common page conversion table only needs a table capacity commensurate with the amount of sharing, and a small shared table can be used. This is effective in realizing page sharing control with a high degree of freedom.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram of page sharing in an embodiment of the present invention, FIG. 2 is a schematic diagram of an address translation table in an embodiment of the present invention, and FIGS. 3 and 4 are a conceptual diagram of page sharing in an embodiment of the present invention. FIG. 5 is a block diagram of an address translation scheme illustrating an embodiment of the present invention. 10.20...Virtual space, 30...Real memory, 50.
...Control register, 6o...Virtual address format, 70
...Shared address translation table directory, 10
0... Address converter, 110, 130... Adder, 120... Page conversion table, 140... Segment table, 141, 142... Entry format of page conversion table, 150... Common page conversion table, 151... common page conversion table en'
43 Figure 5 Figure 5

Claims (1)

[Claims] In a computer that adopts a virtual memory system and is provided with a conversion table that converts a virtual address in each virtual space to a real address on a real storage device, a table shared among the virtual spaces corresponding to several entries in the conversion table is used. 1. An address translation method comprising: a shared address translation table for an area in which the address is to be translated; and means for detecting the shared address translation table from each of the virtual spaces.