2 research outputs found
Problems in characterizing barrier performance
The barrier is a synchronization construct which is useful in separating a parallel program into parallel sections which are executed in sequence. The completion of a barrier requires cooperation among all executing processes. This requirement not only introduces the wait for the slowest process delay which is inherent in the definition of the synchronization, but also has implications for the efficient implementation and measurement of barrier performance in different systems. Types of barrier implementation and their relationship to different multiprocessor environments are described. Then the problem of measuring the performance of barrier implementations on specific machine architecture is discussed. The fact that the barrier synchronization requires the cooperation of all processes makes the problem of performance measurement similarly global. Making non-intrusive measurements of sufficient accuracy can be tricky on systems offering only rudimentary measurement tools
The exploitation of parallelism on shared memory multiprocessors
PhD ThesisWith the arrival of many general purpose shared memory multiple processor
(multiprocessor) computers into the commercial arena during the mid-1980's, a
rift has opened between the raw processing power offered by the emerging
hardware and the relative inability of its operating software to effectively deliver
this power to potential users. This rift stems from the fact that, currently, no
computational model with the capability to elegantly express parallel activity is
mature enough to be universally accepted, and used as the basis for programming
languages to exploit the parallelism that multiprocessors offer. To add to this,
there is a lack of software tools to assist programmers in the processes of designing
and debugging parallel programs.
Although much research has been done in the field of programming languages,
no undisputed candidate for the most appropriate language for programming
shared memory multiprocessors has yet been found. This thesis examines why this
state of affairs has arisen and proposes programming language constructs,
together with a programming methodology and environment, to close the ever
widening hardware to software gap.
The novel programming constructs described in this thesis are intended for use
in imperative languages even though they make use of the synchronisation
inherent in the dataflow model by using the semantics of single assignment when
operating on shared data, so giving rise to the term shared values. As there are
several distinct parallel programming paradigms, matching flavours of shared
value are developed to permit the concise expression of these paradigms.The Science and Engineering Research Council