NPAC Technical Report SCCS-660
A Study of Collective Communication on the KSR-1
Sanjay Goil, Albert Wang, Sanjay Ranka
Submitted August 1 1994
Abstract
In this paper we study the primitives for structured communication
on the Kendall Square Research Multiprocessor KSR-1. Many parallel
applications require operations that involve all the participating
processors or some subset of the
processors. We have studied the primitives for collective communication
and mode led the cost
for each on the ALLCACHE memory . We find that some algorithms with
a large requirement for remote data from processors on the same ring
perform almost as well as the ones that require little communication.
We observe very little node and link contention by multiple processors
referencing data from the same processor.
We also study the use of multiple threads on a single processor and
observe a significant overlap between computation and communication.