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


I/O (n.) refers to the hardware and software mechanisms connecting a computer with its environment. This includes connections between the computer and its disk and bulk storage system and also connections to user terminals, graphics systems, and networks to other computer systems or devices. Standard I/O is a particular software package developed under UNIX for the C programming language.

ICMP (n.) is the internet control message protocol and is used to handle errors and control messges at the internet protocol layer. ICMP is considered to be part of IP and is used to test whether a destination is reachable and responding.

IEEE 802.3 (n.) The standard for Carrier Sense Multiple Access with Collision Detection is one of the most used LAN protocols.

IGP (n.) interior gateway protocol is used to exchange routing information between routers in the internet. It is generally used for routers within an autonomous system. The RIP and OSPF are examples of IGP.

ILMI (n.) Interim Local Management Interface that is the de facto standard until a standard based committee designates a standardized protocol suite. In the last few years ILMI has been popular due to the frequency of changes in the tele-communications industry.

implicitly parallel (n.) language semantics that do not allow the user to explicitly describe which computations are independent and can be performed in parallel. For an implicitly parallel language, the compiler must deduce or prove independence in order to make use of parallel hardware. The comparative difficulty of the deduction separates implicitly parallel languages from explicitly parallel ones.

indirect method (n.) Any technique for solving a system of equations that does not rely on linear algebra directly. Successive over-relaxation is an example of an indirect method. See also direct method.

information (n.) a collection of related data objects.

inner product method (n.) method of matrix multiplication in which one element of the resultant matrix is computed at a time. See also middle product method

input/output (n.) See I/O.

instruction buffering (n.) process of prefetching instructions with the goal of never making the processor wait for an instruction to be fetched. This is sometimes also known as instruction look-ahead.

instruction cache (n.) a cache memory that holds only instructions but not data.

instruction pipelining (n.) strategy of allowing more than one instruction to be in some stage of execution at the same time. See also MISD.

instruction scheduling (n.) a strategy of a compiler to analyse the outcome of the operations specified in a program and to issue instructions in an optimal manner. That is, the instructions are not necessarily issued in the order specified by the programmer, but in an order that optimally uses the registers, functional units and memory paths of the computer, while at the same time guaranteeing correct results for the computation.

instruction set (n.) the set of low level instructions that a computer is capable of executing. Programs expressed in a high level language must ultimately be reduced to these.

instruction stream (n.) sequence of instructions performed by a computer.

interactive vectorizer (n.) an interactive program to help a user vectorize source code. See also true ratio.

interconnection network (n.) the system of logic and conductors that connects the processors in a parallel computer system. Some examples are bus, mesh, hypercube and Omega networks.

interleaved memory (n.) memory divide into a number of modules or banks that can be accessed simultaneously.

internal sort (n.) sorting a table of names contained entirely in primary memory.

interprocessor communication (n.) the passing of data and information among the processors of a parallel computer during the execution of a parallel program.

interprocessor contention (n.) conflicts caused when multiple CPU's compete for shared system resources. For example, memory bank conflicts for a user's code in global memory architectures are caused by other processors running independent applications.

interrupt-driven system (n.) A system whose processes communicate by message passing in such a way that when a message is delivered to its destination process it interrupts execution of that process and initiates execution of an interrupt handler process, which stores the message for subsequent retrieval. On completion of the interrupt-handler process (which sets some flag or sends some signal to denote an available message), the original process resumes execution.

interval routing (n.) A routing algorithm that assigns an integer identifier to each possible destination and then labels the outgoing links of each node with a single contiguous interval or window so that a message can be routed simply by sending it out the link in whose interval its destination identifier falls.

invariant (n.) a variable, especially in a DO-loop, that appears only on the right side of an equals sign. The variable is read only, it is never assigned a new value.

invariant expression (n.) an expression, especially in a DO-loop, all of whose operands are invariant or constant.

IP (n.) The internet protocol that defines the unit of information passed between systems that provides a basis packet devlivery service. It handles best effort connectionless delivery service and includes ICMP. See also IP address.

IP address (n.) The Internet protocol address which is a 32-bit address assigned to a host. The IP address has a host component and a network component.

IPX (n.) Integrated Packet Exchange for example Stratacom's Packet switch for public and private T1 and E1 networks.

IPX/link (n.) This application for NetWare connects a PC Novell NetWare LAN through a network interface device.

IS-IS (n.) intermediate system to intermediate system protocol is the ISO protocol that defines how intermediate systems exchange routing information.

ISO (n.) International Standards Organization, which, among other things, sets standards for programming languages.

ISODE (n.) ISO development environment software provides an ISO transport level protocol interface that resides on top of TCP/IP.

isoefficiency(n.) A way to quantify the effect of scaling problem size on an algorithm's efficiency. For a given efficiency, the isoefficiency function for an algorithm specifies what size of problem must be solved on a given number of processors to achieve that efficiency.

iterative decomposition (n.) a decomposition involving breaking down a calculation in which one or more operations are repeatedly applied to one or more data values by treating each data subset / operation subset as a separate task and distributing tasks amongst available processors, either deterministically or randomly. In a deterministic decomposition, the data to be processed are fixed and the same operations are applied to each. In a speculative decomposition, different operations are applied simultaneously to the same input until at least one has completed. See also functional decomposition and geometric decomposition.

iterative deepening (n.) use of a D-ply search to prepare for a (D+1)-ply search.