High Performance Computing and Communications Glossary 2.1

A significant part of the material of this glossary was adapted from material originally written by Gregory V. Wilson which appeared as "A Glossary of Parallel Computing Terminology" (IEEE Parallel & Distributed Technology, February 1993), and is being re-printed in the same author's "Practical Parallel Programming" (MIT Press, 1995). Several people have contributed additions to this glossary, especially Jack Dongarra, Geoffrey Fox and many of my colleagues at Edinburgh and Syracuse.

Original version is from NPAC at <URL:http://nhse.npac.syr.edu/hpccgloss/>

Original author: Ken Hawick, khawick@cs.adelaide.edu.au

See also the index of all letters and the full list of entries (very large)

Sections: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


UART (n.) Universal Asynchronous Receive-Transmit; a standard protocol for device drivers.

UDP (n.) user datagram protocol is a transport layer protocol in the internet protocol suite. UDP uses IP for packet delivery, and is unreliable, connectionless, and stateless. However, UDP does not use handshaking before exchanging data and therefore acknowledgements and guaranteed delivery are not available. UDP relies on higher protocol layers to provide end to end data delivery and integrity.

UMA (adj.) Uniform memory access; permitting any memory element to be read or written in the same, constant time. See also NUMA.

undirected graph (n.)a graph whose edges have no orientation.

unification (v.) instantiation of a variable with a value.

uniform cost criterion (n.) the assumption that every instruction takes one unit of time and every register requires one unit of space.

uniform memory access (adj.) See UMA.

uniprocessor (n.) A computer containing a single processor. The term is generally synonymous with scalar processor.

UNIX (n.) an OS originally developed by AT&T which, in various incarnations, is now available on most types of supercomputer.

unneeded store (n.) situation resulting when two or more stores into the same memory location without intermediate reads occur in an optimization block, especially within a DO-loop, such that only the last store need actually be performed.

utilization (n.) percentage of time a processor spends executing useful tasks during execution of a program.

uucp (n.) Unix to Unix copy program is a protocol used for communicating between Unix hosts using serial interfaces.