JPS6364146A - Logical space control system - Google Patents

Abstract

PURPOSE:To attain allocation without hardly leaving the resources of an actual memory by providing an allocatable maximum value register, an allocated value register, a user area allocating table, etc. CONSTITUTION:A logical space control part 1, first, investigates whether or not the resources to be able to allocate a request page remain at a user area to which an allocating request is executed. For that reason, the total number of the pages of the allocatable idle area is obtained by subtracting the value of an allocatable maximum value register 2, namely, the value of an allocated value register 3 from the size of the usable resources on the actual memory and this is compared with the size of the request page. As a result, when this is larger than or equal to the size of the request page, a user area allocating table 4 is referred to, respective idle areas and the request page are compared and to the idle area to make sufficient the request page, a user area is first allocated. The user area newly allocated to the table 4 is registered and the allocation can be executed without hardly leaving the resources of the actual memory.

Description

[Detailed Description of the Invention] [Summary] The allocation is made larger than the available area length to provide room for generating a continuous free area, and when allocating a user area to the logical space, a continuous free area of the requested size is allocated. Make it easier to acquire the lI area.

[Industrial application field]

The present invention relates to a virtual storage system in an information processing device, and particularly relates to a logical space (virtual space) management system.

[Conventional technology]

In a virtual storage type information processing apparatus, parallel processing is performed by allocating a storage area of a real memory to a logical space of a plurality of jobs in units of pages.

FIG. 4 shows the correspondence between one logical space and real memory.

In FIG. 4, 41 is a logical space, 42 is a segment table SGT, 43 is a page table PGT, and 44 is a real memory.

! Contains Ijg A 1 Ke-So. Segment table 5GT42 that covers the top of the figure
Then, using the page table PGT43, correspondence with the actual memo IJ44 is performed on a page-by-page basis. logical space 41
For example, the size is 16MB and 256 segments.

The l segment consists of 16 pages, and one page is 4 KB.

The logical space 41 is composed of a system area 2, an individual user area, and a common area. Individual user area.

Contains the region used to load and execute user programs. A region refers to the largest contiguous logical address space that can be allocated to a user program. (Therefore, the region size also determines the maximum real page allocation).

When a user program is executed, an area of the size specified by the REGION parameter of the job control statement JCL (hereinafter referred to as the user area) is reserved for the user (job) by the control program.
It is allocated within the reserved range at the request of the user program, and released after processing is completed.

Typically, the allocation of user space to regions is.

A contiguous HGI area of the requested size from the low address to the high address (or from the fossa address to the low address) within the free space within the region.

This is done by cutting out at certain fixed boundaries.

[Problem that the invention seeks to solve]

In the conventional region user area allocation method described above, as a number of user programs are executed in one logical space and user area allocation and release are repeated, the free space within the region is reduced as shown in Figure 5. As such, they become fragmented (called fragmentation).

As a result, even if a new user area is requested, a contiguous user area of the necessary size is allocated.

There has been a problem in that it becomes increasingly difficult to carve out free space in a region, making it impossible to allocate a large area and making it impossible to execute the user program. In this case, the idea of merging the scattered free areas and reorganizing them into a larger free area was impossible because it would involve changing the logical address given to the user area.

Next, a brief explanation of the fifth drawing will be given.

In the illustrated example, the region is shown in a simplified manner for the sake of convenience, and the entire region is composed of 16 pages, with diagonally shaded pages representing allocated areas and the remaining pages representing free areas. In this case, the total free space is 10 pages, but the maximum continuous free space is 3 pages. Therefore, when a request occurs, a four-page user area is allocated.

Allocation becomes impossible.

[Means for solving problems]

In the conventional method for allocating user areas in regions described above, the size of the region specified by the user is comparable to the size of the region managed by the system, and logical page allocation corresponds to the maximum possible value. However, in the present invention, the size of the region managed by the system is reduced to 5.
The allocation is sufficiently larger than the maximum possible value (specified by the user - the size of the John), and the size of the 3 allocation is equal to the difference between the maximum possible value and the total value of the allocated user area. This allows continuous free space to be extracted at all times.

FIG. 1 shows the basic configuration of the present invention.

In FIG. 1, 1 is a logical space management unit, 2 is a maximum possible value register for allocation, 3 is an already allocated value register, and 4 is a table for user area allocation.

The logical space management unit 1 accepts requests for user area allocation upon job startup and allocates continuous free areas.

It is extracted and allocated from a predetermined section (region) in the logical space.

The maximum possible allocation value register 2 holds the maximum value of resources that can be allocated.

The allocated value register 3 holds the total value of user area lengths O that have been allocated in the logical space of each activated job.

User area allocation table 4 displays the address arrangement of each user area allocated in the logical space of each job.

The logical space management unit 1 subtracts the value held in the maximum value register 3 for 1 allocation from the value held in the maximum possible value register 2 for 9 allocations.

Currently, 1 allocation is recognized as a possible continuous free area length.

The logical space management unit 1 searches for an empty area commensurate with the length of the requested user area for 9 allocation, and for user area allocation, searches from the lower address of the logical space, for example, and searches for the first contiguous area found. Allocate free space. However, if there is no continuous free area of sufficient size between the $1 areas where 1 allocation has been completed, a continuous free area is taken outside the last allocated area and 1 allocation is made.

[Effect]

Next, the present invention will be explained in detail using a specific example shown in FIG.

In FIG. 2, ■ is a predetermined section on the logical space.

■ indicates the maximum possible resource allocation (for simplification).

10 pages), ■ indicates the distribution of currently allocated areas (shaded areas) and free areas (other than the shaded areas), and ■ indicates the longest continuous empty area that can be currently allocated.

The predetermined section (■) on the logical space has 9 allocations that are larger than the maximum possible resource value (■). Distribution ■ indicates that the total available free space for one allocation is 7 pages, and the maximum continuous free space length is 2 pages.

Here, when 1 allocation is assumed that the length of the requested area is 2 pages, the continuous empty area of 2 pages having the lowest address is allocated.

However, if there is a request to allocate an area of 3 or more pages, for example 7 pages, as shown in Set the area and allocate 9. However, the total area length that can be allocated for 1 time cannot be larger than the maximum possible resource size (■) for 1 allocation.

In this way, even if the free areas are finely distributed, they can be easily allocated as continuous free areas.

〔Example〕

The present invention will be explained in detail with reference to FIG.

In FIG. 3, l is a logical space management unit, 2 is a maximum possible value register for allocation, 3 is an already allocated value register, and 4 is a table for user area allocation. In addition, 1 to 4
Each element indicated by is the same as the element with the same number shown in FIG.

Here, the size of the requested user area is assigned to the logical space management unit l in A pages, and the value of the maximum possible value register 2, that is, the size of the resources that can be used on the real memory, is assigned to M pages. , the value of completed value register 3 is allocated to page B, and the user area is allocated to the size of table 4, that is, the logical space -11;
−9 6 f−ρ・−、”; I+
, the size of +1 free space distributed within -11, starting from the one with the smallest address, in terms of the number of pages.

Represented by ml,...1m,...,mk.

The logical space management unit 1 first checks whether there are any resources remaining that can allocate the requested user area size A page. Therefore, 1 allocation is the total number of pages (represented by D) of possible free space.

The following formula Find this and compare it with A. the result.

If D≧A, the secondary user area allocation refers to Table 4, compares each free area mi (i=o, 1..., k) with A sequentially, and fills A first. Allocate user area to free space. Generally, when generating a logical space, the size of C may be determined so that the last free area mk satisfies 9mk≧Σmi.

The result of the allocation is 1 allocated value register 3 and the user area allocation is reflected in table 4, ie 1
The value of the allocated value register 3 becomes B+A-B, and the newly allocated user area is registered in the user area allocation table 4.

Note that even when the user area is released, the reverse process is performed for the 9 allocation completed value register 3 and the user area allocation table 4.

〔Effect of the invention〕

According to the present invention, by making the size of the logical space sufficiently larger than the size of the real memory resources (for example, increasing the bit length of the logical address from 32 bits to 64 bits), the real memory resources can be almost completely used. Allocation is possible without leaving anything behind.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is an explanatory diagram of an example of user area allocation showing the operation of the present invention. FIG. 3 is a configuration diagram of an embodiment of the present invention, FIG. 4 is an explanatory diagram of the correspondence between logical space and real memory, and FIG. 5 is an explanatory diagram of an example of a conventional user area allocation method. In Figure 1. 1: Logical space management unit 2: Allocation is maximum possible value register 3: Allocation completed value register

Claims (1)

[Claims] In a virtual memory type information processing device, the size of a predetermined section to which a user area can be allocated in the logical space of each activated job is set larger than the size of the resource to which a user area can be allocated in real memory. When allocating a user area in space, within the total length of free space in the resources to which the user area can be allocated in real memory,
A logical space management method characterized by cutting out and allocating an area of a necessary size from continuous free areas within a predetermined section on the logical space.