The InfiniBand Architecture (IBA) is a new industry-standard architecture for server I/O and inter-server communication. It was developed by the InfiniBandSM Trade Association (IBTA) to provide the levels of reliability, availability, performance, and scalability necessary for present and future server systems, levels significantly better than can be achieved with bus-oriented I/O structures. This paper provides a brief description of IBA.

Summary form only given, as follows. This keynote covers past and future history of clusters. It will extrapolate the future from an observable cycle of cluster creation that has recurred several times in the past, combining that with the pieces and the glue that will be available in the future.

A parallel simulator, PSIMUL, has been used to collect information on the memory access patterns and synchronization overheads of several scientific applications. The parallel simulation method we use is very efficient and it allows us to simulate execution of an entire application program, amounting to hundreds of millions of instructions. We present our measurements on the memory access characteristics of these applications; particularly our observations on shared and private data, their frequency of access and locality. We have found that, even though the shared data comprise the largest portion of the data in the application program, on the average a small fraction of the memory references are to shared data. The low averages do not preclude bursts of traffic to shared memory nor does it rule out positive benefits from caching shared data. We also discuss issues of synchronization overheads and their effect on performance.

The IBM Yorktown Simulation Engine (YSE) is a special-purpose, highly parallel programmable machine for the gate-level simulation of logic. A YSE has been constructed at the IBM T. J. Watson Research Center. A full configured YSE could simulate up to two million gates at a speed of over three billion gate simulations per second, it is estimated that a YSE could simulate an IBM 3081 processor, at the gate level, at a rate of 1000 System/370 instructions per second. This paper describes the YSE architecture and software support.

The combining of messages within a multistage switching network has been proposed to reduce memory contention in highly parallel shared-memory multiprocessors, especially for shared lock and synchronization data. A quantitative investigation of the performance impact of such contention and the effectiveness of combining in reducing this impact is reported. The effect of a nonuniform traffic pattern consisting of a single hot spot of higher access rate superimposed on a background of uniform traffic was investigated. The potential degradation due to even moderate hot spot traffic was found to be very significant, severely degrading all memory access, not just access to shared lock locations, due to an effect the authors call tree saturation. The technique of message combining was found to be an effective means of eliminating this problem if it arises due to lock or synchronization contention.

The Yorktown Simulation Engine (YSE) is a special-purpose, highly-parallel programmable machine for the gate-level simulation of logic. The YSE has been designed and is being constructed at the IBM T. J. Watson Research Center. It can simulate up to one million gates at a speed of over two billion gate simulations per second; it is estimated that the IBM 3081 processor could have been simulated on the YSE at a rate of 1000 instructions per second. This is far beyond the capabilities of existing register-level software simulators. This paper describes the software support for the YSE.

The Yorktown Simulation Engine (YSE) is a special-purpose, highly-parallel programmable machine for the gate-level simulation of logic. It can simulate up to one million gates at a speed of over two billion gate simulations per second; it is estimated that the IBM 3081 processor could have been simulated on the YSE at a rate of 1000 instructions per second. This is far beyond the capabilities of existing register-level software simulators. The YSE has been designed and is being constructed at the IBM T. J. Watson Research Center. This paper introduces the YSE and describes its top-level architecture.

The development of interactive, display oriented systems for the manipulation of online information has traditionally been an extremely difficult and prohibitively expensive effort. This paper describes an approach based on the concept of interaction oriented specification and execution of applications and state networks. The general approach is described and then illustrated with a current display application development product.