In this paper, we present an early performance evaluation of a 624-core cluster based on the Intel® Xeon® Processor 5560 (code named "Nehalem-EP", and referred to as Xeon 5560 in this paper)---the third-generation quad-core architecture from Intel. This is the first processor from Intel with a non-uniform memory access (NUMA) architecture managed by on-chip integrated memory controller. It employs a point-to-point interconnect called the Intel® QuickPath Interconnect (QPI) between processors and to the input/output (I/O) hub. It also introduces to a quad-core architecture both Intel's hyper-threading technology (or simultaneous multi-threading, "SMT") and Intel® Turbo Boost Technology ("Turbo mode") that automatically allow processor cores to run faster than the base operating frequency if the processor is operating below rated power, temperature, and current specification limits. It can be engaged with any number of cores or logical processors enabled and active. We critically evaluate these features using the High Performance Computing Challenge (HPCC) benchmarks, NAS Parallel Benchmarks (NPB), and four full-scale scientific applications. We compare and contrast the results of a cluster based on the Xeon 5560 with an SGI® Altix® ICE 8200EX cluster of quad-core Intel® Xeon® 5472 Processor ("Xeon 5472" from here on) and another cluster of Intel® Xeon® 5462 Processor ("Xeon 5462"; the Xeon 5400 Series Processors are previous generation quad-core Intel processors and were code named Harpertown).

David Barkai is a member of the Distributed Systems Lab of Intel's Corporate Technology Group. He has also been a content architect for the Intel Developer Forum conference and a software scientist in the Microcomputer Software Lab. Before joining Intel in 1996, David worked for 25 years in the field of scientific and engineering supercomputing for Control Data Corporation, Cray Research Inc., Supercomputer Systems Inc., and NASA Ames Research Center.

This paper is an overview of the technologies that are needed for Peer-to-Peer (P2P) computing. It represent a high level overview of material covered in much greater detail in Barkai, (2001). P2P means different things to different people, and we start by defining P2P and categorizing applications that use P2P. Server-mediated P2P is included as a legitimate P2P architecture. The applications space is divided into three types: distributing computing, content sharing, and collaboration. After a discussion of what is required from an infrastructure for P2P we describe some solutions that address a class of applications each, but also include a start towards a general-purpose architecture. The same basic services are needed by each platform and application, and all will benefit from common middleware. This is one way, though not the only one, to achieve interoperability - that will be useful to users and application developers; in particular, when we reach the integrated applications stage. Regardless of how the infrastructure is constructed, the technical topics which need to be addressed are the same: communication through gateways and firewalls; naming and discovery of peers and resources when DNS is not enough; availability and persistence of resources in spite of intermittent connectivity and dynamic presence; security in a distrustful environment and locally managed systems; and, management of distributed resources in a heterogeneous setting. There are a number of interesting ways in which people have applied P2P technologies. We give an example in each of the three application categories. The final segment of the talk summarizes the challenges that need to be overcome if P2P is to be widely adopted. The major technical challenges are direct communication, security, naming and interoperability. There are also social and cultural barriers. These are the result of decentralization, and loss of direct control over resources. They also have to do with trust, reputation, and online communities. Nonetheless, there are some promising activities around the industry-working groups and initiatives, and a great opportunity.