Exploiting Spatial and Temporal Locality of Accesses: A New
           Hardware-Based Monitoring Approach for DSM Systems

            Robert Hockauf, Wolfgang Karl, Markus Leberecht, 
                    Michael Oberhuber, Michael Wagner

              Lehr- und Forschungseinheit Informatik X
          Rechnertechnik und Rechnerorganisation (LRR-TUM)
                    Institut für Informatik der 
                  Technischen Universität München
              Arcisstr. 21, D-80290 München, Germany
                 karlw@informatik.tu-muenchen.de

                            Abstract

The performance of a parallel system with NUMA characteristics depends
on the efficient use of local memory accesses. Programming and tool
environments for such DSM systems should enable and exploit data
locality.

In this paper we present an event-driven hybrid monitoring concept
for the SMiLE SCI-based PC cluster. The central part of the hardware
monitor consists of a content-addressable counter array managing  a
small working set of the most recently referenced memory regions. We
show that this approach allows to provide detailed run-time
information which can be exploited by  performance evaluation and
debugging tools.