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distributed shell (dsh). An Parallel System Support
Programs command that lets you issue commands to a
group of hosts in parallel. See
IBM Parallel System
Support Programs for AIX: Command and Technical
Reference
for details.
domain name. The hierarchical identification of a host
system (in a network), consisting of human-readable
labels, separated by decimals.
E
environment variable. 1. A variable that describes the
operating environment of the process. Common
environment variables describe the home directory,
command search path, and the current time zone. 2. A
variable that is included in the current software
environment and is therefore available to any called
program that requests it.
event. An occurrence of significance to a task; for
example, the completion of an asynchronous operation
such as an input/output operation.
Ethernet. Ethernet is the standard hardware for
TCP/IP LANs in the UNIX marketplace. It is a 10
megabit per second baseband type network that uses
the contention based CSMA/CD (collision detect) media
access method.
executable. A program that has been link-edited and
therefore can be run in a processor.
execution. To perform the actions specified by a
program or a portion of a program.
expression. In programming languages, a language
construct for computing a value from one or more
operands.
F
fairness. A policy in which tasks, threads, or
processes must be allowed eventual access to a
resource for which they are competing. For example, if
multiple threads are simultaneously seeking a lock, then
no set of circumstances can cause any thread to wait
indefinitely for access to the lock.
FDDI. Fiber distributed data interface (100 Mbit/s fiber
optic LAN).
file system. In the AIX operating system, the
collection of files and file management structures on a
physical or logical mass storage device, such as a
diskette or minidisk.
fileset. 1) An individually installable option or update.
Options provide specific function while updates correct
an error in, or enhance, a previously installed product.
2) One or more separately installable, logically grouped
units in an installation package. See also
Licensed
Program Product
and
package
.
foreign host. See
remote host
.
Fortran. One of the oldest of the modern programming
languages, and the most popular language for scientific
and engineering computations. It's name is a
contraction of
FORmula TRANslation
. The two most
common Fortran versions are Fortran 77, originally
standardized in 1978, and Fortran 90. Fortran 77 is a
proper subset of Fortran 90.
function call tree. A graphical representation of all the
functions and calls within an application, which appears
in the Xprofiler main window. The functions are
represented by green, solid-filled rectangles called
function boxes. The size and shape of each function
box indicates its CPU usage. Calls between functions
are represented by blue arrows, called call arcs, drawn
between the function boxes. See also
call arcs
.
function cycle. A chain of calls in which the first caller
is also the last to be called. A function that calls itself
recursively is not considered a function cycle.
functional decomposition. A method of dividing the
work in a program to exploit parallelism. One divides
the program into independent pieces of functionality
which are distributed to independent processors. This is
in contrast to data decomposition which distributes the
same work over different data to independent
processors.
functional parallelism. Refers to situations where
parallel tasks specialize in particular work.
G
Gauss-Seidel. An iterative relaxation method for
solving Laplace's equation. It calculates the general
solution by finding particular solutions to a set of
discrete points distributed throughout the area in
question. The values of the individual points are
obtained by averaging the values of nearby points.
Gauss-Seidel differs from Jacobi-Seidel in that for the
i+1st iteration Jacobi-Seidel uses only values calculated
in the ith iteration. Gauss-Seidel uses a mixture of
values calculated in the ith and i+1st iterations.
global max. The maximum value across all
processors for a given variable. It is global in the sense
that it is global to the available processors.
global variable. A variable defined in one portion of a
computer program and used in at least one other
portion of the computer program.
Glossary of Terms and Abbreviations 189