Cray Incorporated

Allan Porterfield

Burton Jordan Smith

Brian D Koblenz

Charles David Callahan, Ii

Gail A Alverson

Simon H Kahan

Various techniques for manipulating data using access states of memory, access control fields of pointers and operations, and exception raising and exception trapping in a multithreaded computer system. In particular, the techniques include synchronization support for a thread blocked in a word, demand evaluation of values, parallel access of multiple threads to a list, synchronized and unsynchronized access to a data buffer, use of forwarding to avoid checking for an end of a buffer, use of sentinel word to detect access past a data structure, concurrent access to a word of memory using different synchronization access modes, and use of trapping to detect access to restricted memory.

Synchronization techniques in a multithreaded environment

Various techniques for manipulating data using access states of memory, access control fields of pointers and operations, and exception raising and exception trapping in a multithreaded computer system. In particular, the techniques include synchronization support for a thread blocked in a word, demand evalution of values, parallel access of multiple threads to a list, synchronized and unsynchronized access to a data buffer, use of fowarding to avoid checking for an end of a buffer, use of sentinel work to detect access past a data structure, concurrent access to a word of memory using different synchronization access modes, and use of trapping to detect access to restricted memory.

Accessing a collection of data items in a multithreaded environment

Detecting access to a memory location in a multithreaded environment

Restricting access to memory in a multithreaded environment

A method and system for allocating memory. The computer system on which the memory allocation system executes may support the simultaneous execution of multiple threads. Under control of a thread, the memory allocation system first identifies a bin associated with blocks (&ldquo;lockers&rdquo;) of memory large enough to satisfy a memory allocation request. When the identified bin has a free locker, the memory allocation system searches a circular list of headers associated with the identified bin for a collection of lockers (&ldquo;warehouse&rdquo;) that contains a locker that is available to be allocated. The memory allocation system allocates the found available locker to satisfy the request. If, however, the allocated bin has no free lockers, the memory allocation system allocates a warehouse with lockers large enough to satisfy the memory allocation request. The memory allocation system then adds a warehouse header for the allocated warehouse to a circular list of warehouse headers associated with the identified bin. The memory allocation system allocates a locker from the newly allocated warehouse to satisfy the memory allocation request.

Method and system for memory allocation in a multiprocessing environment

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Bellevue, WA, United States of America

Allan Porterfield