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buffer. A portion of storage used to hold input or
output data temporarily.
C
C. A general purpose programming language. It was
formalized by ANSI standards committee for the C
language in 1984 and by Uniforum in 1983.
C++. A general purpose programming language, based
on C, which includes extensions that support an
object-oriented programming paradigm. Extensions
include:
strong typing
data abstraction and encapsulation
polymorphism through function overloading and
templates
class inheritance.
call arc. The representation of a call between two
functions within the Xprofiler function call tree. It
appears as a solid line between the two functions. The
arrowhead indicates the direction of the call; the
function it points to is the one that receives the call. The
function making the call is known as the
caller
, while
the function receiving the call is known as the
callee
.
chaotic relaxation. An iterative relaxation method
which uses a combination of the Gauss-Seidel and
Jacobi-Seidel methods. The array of discrete values is
divided into sub-regions which can be operated on in
parallel. The sub-region boundaries are calculated using
Jacobi-Seidel, whereas the sub-region interiors are
calculated using Gauss-Seidel. See also
Gauss-Seidel
.
client. A function that requests services from a server,
and makes them available to the user.
cluster. A group of processors interconnected through
a high speed network that can be used for
high-performance computing. It typically provides
excellent price/performance.
collective communication. A communication
operation which involves more than two processes or
tasks. Broadcasts, reductions, and the MPI_Allreduce
subroutine are all examples of collective communication
operations. All tasks in a communicator must
participate.
command alias. When using the PE command line
debugger, pdbx, you can create abbreviations for
existing commands using the pdbx alias command.
These abbreviations are know as
command aliases
.
Communication Subsystem (CSS). A component of
the Parallel System Support Programs that provides
| software support for the SP Switch. CSS provides two
protocols: IP (Internet Protocol) for LAN-based
communication and US (user space) as a message
passing interface that is optimized for performance over
the switch. See also
Internet Protocol
and
User Space.
communicator. An MPI object that describes the
communication context and an associated group of
processes.
compile. To translate a source program into an
executable program.
condition. One of a set of specified values that a data
item can assume.
control workstation. A workstation attached to the
IBM RS/6000 SP SP that serves as a single point of
control allowing the administrator or operator to monitor
and manage the system using Parallel System Support
Programs.
core dump. A process by which the current state of a
program is preserved in a file. Core dumps are usually
associated with programs that have encountered an
unexpected, system-detected fault, such as a
Segmentation Fault, or severe user error. The current
program state is needed for the programmer to
diagnose and correct the problem.
core file. A file which preserves the state of a
program, usually just before a program is terminated for
an unexpected error. See also
core dump
.
current context. When using either of the PE parallel
debuggers, control of the parallel program and the
display of its data can be limited to a subset of the
tasks that belong to that program. This subset of tasks
is called the
current context
. You can set the current
context to be a single task, multiple tasks, or all the
tasks in the program.
D
data decomposition. A method of breaking up (or
decomposing) a program into smaller parts to exploit
parallelism. One divides the program by dividing the
data (usually arrays) into smaller parts and operating on
each part independently.
data parallelism. Refers to situations where parallel
tasks perform the same computation on different sets of
data.
dbx. A symbolic command line debugger that is often
provided with UNIX systems. The PE command line
debugger, pdbx, is based on the dbx debugger.
debugger. A debugger provides an environment in
which you can manually control the execution of a
program. It also provides the ability to display the
program's data and operation.
188 IBM PE for AIX V2R4.0: Messages