International Business Machines Corporation

Anthony Simon Bolmarcich

Julian Satran

Roch Georges Archambault

Sandra Johnson Baylor

Ching-Farn Eric Wu

Yarsun Hsu

Maria Eleftheriou

Siddhartha Chatterjee

Peter Frank Corbett

Raymond Mak

G Calin Cascaval

An improved scalability runtime system for a global address space language running on a distributed or shared memory machine uses a directory of shared variables having a data structure for tracking shared variable information that is shared by a plurality of program threads. Allocation and de-allocation routines are used to allocate and de-allocate shared variable entries in the directory of shared variables. Different routines can be used to access different types of shared data. A control structure is used to control access to the shared data such that all threads can access the data at any time. Since all threads see the same objects, synchronization issues are eliminated. In addition, the improved efficiency of the data sharing allows the number of program threads to be vastly increased.

Scalable runtime system for global address space languages on shared and distributed memory machines

The invention is a system and method for establishing a communication connection between two programs, each running on multiple processors of a distributed or shared memory parallel computer, or on multiple computers in a cluster of workstations or a set of network connected workstations. The invention includes all protocols that require one of the two programs that wish to communicate to actively initiate the communication session, while the other program passively accepts such direct communication session initiations. No task of the active program of the connection will attempt to communicate with tasks of the passive program until after it has been notified that all passive program tasks are prepared to receive messages, and that all other active program tasks are prepare to receive messages from the passive programs tasks, and vice versa. Further, the tasks of the passive program are free running during establishment of the connection; while the active program tasks are free to run provided that they do not attempt to communicate with the second program. Another aspect of the invention provides a secondary indirect communication channel mediated by as resource manager separate from the active and passive programs.

System and method for establishing direct communication between parallel programs

A method of reducing false sharing in a shared memory system by enabling two caches to modify the same line at the same time. More specifically, with this invention a lock associated with a segment of shared memory is acquired, where the segment will then be used exclusively by processor of the shared memory system that has acquired the lock. For each line of the segment, an invalidation request is sent to a number of caches of the system. When a cache receives the invalidation request, it invalidates each line of the segment that is in the cache. When each line of the segment is invalidated, an invalidation acknowledgement is sent to the global directory. For each line of the segment that has been updated or modified, the update data is written back to main memory. Then, an acquire signal is sent to the requesting processor which then has exclusive use of the segment.

Cache coherence for lazy entry consistency in lockup-free caches

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Carmel, NY, United States of America

Anthony Simon Bolmarcich