Impact of Network Sharing in Multi-core Architectures

Narayanaswamy, Ganesh and Balaji, Pavan and Feng, Wu-chun (2008) Impact of Network Sharing in Multi-core Architectures. Technical Report TR-08-06, Computer Science, Virginia Tech.

Abstract

As commodity components continue to dominate the realm of high-end computing, two hardware trends have emerged as major contributors to this - high-speed networking technologies and multi-core architectures. Communication middleware such as the Message Passing Interface (MPI) use the network technology for communicating between processes that reside on different physical nodes while using shared memory for communicating between processes on different cores within the same node. Thus, two conflicting possibilities arise: (i) with the advent of multi-core architectures, the number of processes that reside on the same physical node and hence share the same physical network can potentially increase significantly resulting in {\em increased} network usage and (ii) given the increase in intra-node shared-memory communication for processes residing on the same node, the network usage can potentially {\em reduce} significantly. In this paper, we address these two conflicting possibilities and study the behavior of network usage in multi-core environments with sample scientific applications. Specifically, we analyze trends that result in increase or decrease of network usage and derive insights on application performance based on these. We also study the sharing of different resources in the system in multi-core environments and identify the contribution of the network in this mix. Finally, we study different process allocation strategies and analyze their impact on such network sharing.