04742447 is referenced by 113 patents and cites 11 patents.

A method for accessing information in a page segmented virtual memory data processing system in which virtual machines running UNIX type operating systems are concurrently established, and in which a memory manager controls the transfer of information between primary and secondary storage devices in response to the occurrence of page faults.

The method establishes a plurality of data structures in a dynamic manner in response to a Supervisor call to "map" a file. The mapping process assigns a new segment of virtual memory to the mapped file and correlates, in one data structure, the virtual address of each page of data in the new segment to a disk file address where that page is actually stored.

A UNIX system call by an application program for a specific virtual page is handled by the page fault hanger, and not the UNIX kernel, since the application can supply the real address of the page on the disk file from the data structure that was created by the mapped page range Supervisor call.

Simple load and store type of instructions are employed for the data transfer, which avoids much of the overhead that normally accompanies conventional UNIX read and write system calls to the storage subsystem.

Title
Method to control I/O accesses in a multi-tasking virtual memory virtual machine type data processing system
Application Number
6/819458
Publication Number
4742447
Application Date
January 16, 1986
Publication Date
May 3, 1988
Inventor
Anthony D Hooten
Round Rock
TX, US
Keith E Duvall
Georgetown
TX, US
Agent
Richard E Cummins
Assignee
International Business Machines Corporation
NY, US
IPC
G06F 12/08
G06F 13/00
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