Digital Equipment Corporation

Other

Hewlett-packard Development Company, L.P.

Compaq Information Technologies Group, L.p.

Thomas R Benson

Karen Lee Noel

Michael Seward Harvey

James R Kauffman

Ronald F Brender

Kenneth W Cowan

Gregory H Jordan

Paul Karl Harter, Jr

Mark E Arsenault

Leonard S Szubowicz

Cheryl D Stocks

Richard E Peterson

Mark W Davis

Gary M Barton

A method and system for ordering equitable access to a limited resource (such as a spinlock) by a plurality of contenders (such as processors) where each of the contenders contends for access more than one time. The method classifies one or more contenders that have failed to gain access to the limited resource after at least a predetermined number of attempts as abused contenders. The abused contenders attempt among themselves to gain access to the limited resource. The method repeats the above until all of the abused contenders have gained access to the limited resource.

Ensuring fairness in a multiprocessor environment using historical abuse recognition in spinlock acquisition

Multiple instances of operating systems execute cooperatively in a single multiprocessor computer wherein all processors and resources are electrically connected together. The single physical machine with multiple physical processors and resources is subdivided by software into multiple partitions, each with the ability to run a distinct copy, or instance, of an operating system. At different times, different operating system instances may be loaded on a given partition. Resources, such as CPUs and memory, can be dynamically assigned to different partitions and used by instances of operating systems running within the machine by modifying the configuration. The partitions themselves can also be changed without rebooting the system by modifying the configuration tree. A grouping of partitions, a community, shares memory. Memory may be private to a particular partition or may be shared by partitions within a community. When a community is formed the creating instance reads a configuration tree and builds management structures for the shared memory owned by the community. A single system may have one or more communities, each with their own representation within the configuration tree.

Method and apparatus for dynamically sharing memory in a multiprocessor system

A new system and method for outswapping a process is disclosed. The new system forms one or more working set list chains (also referred to as 'page table chains') during the outswap process. The new system then conveniently locates and outswaps a number of page table pages of the process to be outswapped by traversing the working set list chains. In a preferred embodiment, the forming of each working set list chain is performed while traversing a working set list during outswapping of a number of body pages of a process. Each working set list entry potentially describes a page of virtual memory in use by the process to be outswapped. In a further aspect of the disclosed system, traversing the working set list of the process to be outswapped includes determining whether each one of the working set list entries indicates a private page table page. If an entry in the working set list indicates a private page table page, the present system adds a link to a working set list chain. In the disclosed system, a working set list entry is determined to indicate a private page table page if the page of virtual memory described by the working set list entry is within a page table structure associated with said process. The page table structure is hierarchical, and a separate working set chain is formed for one or more individual levels of the page table hierarchy.

Array index chaining for tree structure save and restore in a process

A method executed in a computer system for detecting and handling an invalid use of a data structure is described. The method includes the steps of providing a data structure associated with a first computing environment. The data structure includes a field having a value stored therein identifying an inaccessible address in a second computing environment. This field is used in detecting an invalid use of the data structure in the second computing environment by a computer program attempting to access memory using said inaccessible address indicated by said value contained in the first field. Additionally a preferred data structure is described as are alternative embodiments of detecting an invalid use of a data structure.

Method and apparatus for handling and detecting an invalid use of a data

A code translator, constructed similar to a compiler, accepts as an input to be translated the assembly code written for one architecture (e.g., VAX), and produces as an output object code for a different machine architecture (e.g., RISC). The input code is converted into an intermediate language, and a flow graph is constructed. The flow graph is referenced by a flow analyzer for recognizing certain architecture-specific and calling standard-specific coding practices or idioms that cannot be automatically converted, particularly relating to stack usage, register usage, condition codes, and passing arguments for procedure calls. By tracking stack usage within routines, the compiler can distinguish up-level stack and return address references from valid local references. Also, it can inform the user of stack misalignment, which has a severe performance penalty, and can detect code segments where different flow paths may result in different stack depths at runtime, which may indicate a source code error. Register usage is likewise tracked to determine which registers are destroyed by a routine, and generate routine prologue and epilogue code which performs register saves, as well as provide register 'hints' to aid the user in adding an entry point declaration or documentation for the routine. The usage of condition codes is likewise tracked, by a backward walk through the flow graph, so that code to fabricate needed values is generated. In addition, all argument pointer based memory references in the input code is tracked to determine how the same argument reference may be made in the target environment.

Tracking condition codes in translation code for different machine

Register usage tracking in translating code for different machine

Mapping assembly language argument list references in translating code

Use of stack depth to identify architechture and calling standard

Growing community of inventors

Hollis, NH, United States of America

Thomas R Benson