Bull Hn Information Systems, Inc.

Ron B Perry

Thomas S Hirsch

Richard S Bianchi

Kenneth J Buck

The main storage of a system includes a virtual memory space containing a plurality of virtual frame buffers for storing information transferred from disk storage shared by a number of virtual processes being executed by the system. An associated buffer table and aging mechanism includes a buffer table storing a plurality of buffer table entries associated with the corresponding number of virtual buffers used for controlling access thereto and an age table containing entries associated with the buffer table entries containing forward and backward age pointers linked together defining the relative aging of the virtual frame buffers from the most recently used to least recently used. Each buffer table entry has a frequency reference counter which maintains a reference count defining the number of times that its associated virtual buffer has been uniquely accessed by the virtual processes. When a virtual frame buffer is required to made available as a replacement candidate, the system's input/output process scans the buffer table entries starting with the least recently used entry to locate an available buffer and examines reference counts contained in the buffer table entries and values derived from the age table indicating the depth or distance that such buffer table entries are from the least recently used position. When the frequency reference count and depth of a particular virtual buffer entry meets defined thresholds, the associated virtual buffer is used as the replacement candidate and its buffer entry is moved to a most recently used position by updating the age table forward and backward pointer entries.

High performance mechanism for managing allocation of virtual memory

A host data processing system which includes a plurality of input/output devices operates under the control of an enhanced version of the UNIX operating system. The host system includes an emulator which runs as an application process for executing user emulated system (ES) application programs. The emulator includes a number of emulated system executive service components operating in shared memory and an interpreter, an emulator monitor call unit (EMCU) and a number of server facilities operating in the host memory. The ES executive service components are extended to accommodate a number of dual decor commands and functions which make host system facilities directly available to ES application programs by concurrent execution of program operations within both the emulator and host system environments. The EMCU includes mechanisms for performing an initial level security validation operation which allows subsequent trusted verification of user identity when dual decor commands or functions are invoked. The server facilities include mechanisms for performing a two-step security validation process for ensuring security relative to preventing both unauthorized user access and compromises in user data through improper use of dual decor commands or functions.

Dual decor capability for a host system which runs emulated application

A host data processing system which includes a plurality of input/output devices operates under the control of an enhanced version of the UNIX operating system. The host system includes an emulator which runs as an application process for executing user emulated system (ES) application programs. The emulator includes a number of emulated system executive service components operating in shared memory and an interpreter, an emulator monitor call unit (EMCU) and a number of server facilities operating in the host memory. The ES executive service command handler and file management components are extended to accommodate and to to allow creation and access to linked files within both host and emulated system files. The server facilities include mechanisms for performing trusted user level validation when a command invokes the access of such a linked file and access checking at file access time which ensures security relative to preventing both unauthorized user access and compromises in host file system data by improper use of linked files.

Mechanism for linking together the files of emulated and host system for

A host data processing system which includes a plurality of input/output devices operates under the control of an enhanced version of the UNIX operating system. The host system includes an emulator which runs as an application process for executing user emulated system (ES) application programs. The emulator includes a number of emulated system executive service components operating in shared memory and an interpreter, an emulator monitor call unit (EMCU) and a number of server facilities operating in the host memory. The ES executive service command handler and file management components are extended to accommodate dual decor copy command which invokes the file management component to copy files in either direction between the host system and emulated system. The server facilities include mechanisms for performing a trusted user level validation when the dual decor copy command is invoked and access control checking at file access which ensures security relative to preventing both unauthorized user access and compromises in user data through improper use of the copy command.

Growing community of inventors

Wilton, NH, United States of America

Ron B Perry