Virtual memory managing system for managing swap-outs by page units and a batch swap-out by task units

A virtual memory managing system comprising:

• swap management tables provided with items referred to as page tag, update bit, and copy bit for each page of a virtual memory space containing a plurality of segments;
• memory area reserving means for, based on a memory area reserve request from a task, creating and managing said swap management table that corresponds to that memory area reserve request;
• reserving, for that memory area reserve request, physical memory areas in a main storage device, segments in virtual memory space, and swap files in an auxiliary storage device;
• and setting information in said swap management table by means of the reservation of these memory areas;
• swap-out control means for, when swap-out becomes necessary, determining whether swap-out should be carried out in page units or batch swap-out should be carried out in task units;
• controlling and executing swap-out based on this determination;
• and setting information indicating that pages that are subject to swap-out have been copied to swap files in said auxiliary storage device in copy bits for these pages in said swap management table;
• memory writing managing means for, when data in said pages have been updated, setting information indicating update of these pages in update bits for these page in said swap management table;
• and
• swap-out object limiting means for effecting control such that, when batch swap-out is carried out in task units under the control of said swap-out control means, swap-out is not carried out for pages that have been copied without being updated based on update bits and copy bits in said swap management table.

A record medium on which programs are recorded, comprising:

• a program for causing a computer in a virtual memory managing system to function as a memory area reserving means that, based on a memory area reserve request from a task, reserves physical memory areas in a main storage device, segments in virtual memory space, and swap files in an auxiliary storage device;
• a program for causing said computer to function as a swap-out control means that, when swap-out becomes necessary, determines whether swap-out should be carried out in page units or batch swap-out should be carried out in task units, and then controls and executes swap-out based on this determination;
• and
• swap-out object limiting means, wherein swap-out is not carried out for pages that have been copied without being updated.

A record medium on which programs are recorded, comprising:

• a program for causing a computer in a virtual memory system to function as a memory area reserving means that, based on a memory area reserve request from a task, creates and manages a swap management table that is provided with items referred to as page tag, update bit, and copy bit;
• reserves, for that memory area reserve request, physical memory areas in a main storage device, segments in virtual memory space, and swap files in an auxiliary storage device;
• and sets information in said swap management table that reflects the reservation of these memory areas;
• a program for causing said computer to function as swap-out control means that, when swap-out becomes necessary, determines whether swap-out should be carried out in page units or batch swap-out should be carried out in task units;
• controls and executes swap-out based on this determination;
• and sets information indicating that pages that are subject to swap-out have been copied to swap files in said auxiliary storage device in copy bits for these pages in said swap management table;
• a program for causing said computer to function as memory writing managing means that, when data in pages have been updated, sets information indicating update of these pages in update bits for these pages in said swap management table;
• and
• a program for causing said computer to function as swap-out object limiting means that effects control such that, when batch swap-out is carried out in task units under the control of said swap-out control means, swap-out is not carried out for pages that have been copied without being updated based on update bits and copy bits in said swap management tables.