Modeling and measurement of fault-tolerant multiprocessors

The workload effects on computer performance are addressed first for a highly reliable unibus multiprocessor used in real-time control. As an approach to studing these effects, a modified Stochastic Petri Net (SPN) is used to describe the synchronous operation of the multiprocessor system. From this model the vital components affecting performance can be determined. However, because of the complexity in solving the modified SPN, a simpler model, i.e., a closed priority queuing network, is constructed that represents the same critical aspects. The use of this model for a specific application requires the partitioning of the workload into job classes. It is shown that the steady state solution of the queuing model directly produces useful results. The use of this model in evaluating an existing system, the Fault Tolerant Multiprocessor (FTMP) at the NASA AIRLAB, is outlined with some experimental results. Also addressed is the technique of measuring fault latency, an important microscopic system parameter. Most related works have assumed no or a negligible fault latency and then performed approximate analyses. To eliminate this deficiency, a new methodology for indirectly measuring fault latency is presented

Simulation experiments for performance analysis of multiple-bus multiprocessor systems with nonexponential service times

A simulation model (program) is constructed for performance analysis of multiple-bus multiprocessor systems with shared memories. It is assumed that the service time of the common memory is either hypo- or hyperexponentially distributed. Process ing efficiency is used as the performance index. To investigate the effects of different service time distributions on the system perfor mance, comparative results are obtained for a large set of input parameters. The simulation results show that the error in approx imating the memory access time by an exponentially distributed random variable is less than 6% if the coefficient of variation is less than 1, but it increases drastically with this factor if it is greater than 1.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68518/2/10.1177_003754978905200104.pd

Development and evaluation of a fault-tolerant multiprocessor (FTMP) computer. Volume 4: FTMP executive summary

The FTMP architecture is a high reliability computer concept modeled after a homogeneous multiprocessor architecture. Elements of the FTMP are operated in tight synchronism with one another and hardware fault-detection and fault-masking is provided which is transparent to the software. Operating system design and user software design is thus greatly simplified. Performance of the FTMP is also comparable to that of a simplex equivalent due to the efficiency of fault handling hardware. The FTMP project constructed an engineering module of the FTMP, programmed the machine and extensively tested the architecture through fault injection and other stress testing. This testing confirmed the soundness of the FTMP concepts

Evaluation of reliability modeling tools for advanced fault tolerant systems

The Computer Aided Reliability Estimation (CARE III) and Automated Reliability Interactice Estimation System (ARIES 82) reliability tools for application to advanced fault tolerance aerospace systems were evaluated. To determine reliability modeling requirements, the evaluation focused on the Draper Laboratories' Advanced Information Processing System (AIPS) architecture as an example architecture for fault tolerance aerospace systems. Advantages and limitations were identified for each reliability evaluation tool. The CARE III program was designed primarily for analyzing ultrareliable flight control systems. The ARIES 82 program's primary use was to support university research and teaching. Both CARE III and ARIES 82 were not suited for determining the reliability of complex nodal networks of the type used to interconnect processing sites in the AIPS architecture. It was concluded that ARIES was not suitable for modeling advanced fault tolerant systems. It was further concluded that subject to some limitations (the difficulty in modeling systems with unpowered spare modules, systems where equipment maintenance must be considered, systems where failure depends on the sequence in which faults occurred, and systems where multiple faults greater than a double near coincident faults must be considered), CARE III is best suited for evaluating the reliability of advanced tolerant systems for air transport

Advanced software techniques for space shuttle data management systems Final report

Airborne/spaceborn computer design and techniques for space shuttle data management system

A fault-tolerant multiprocessor architecture for aircraft, volume 1

A fault-tolerant multiprocessor architecture is reported. This architecture, together with a comprehensive information system architecture, has important potential for future aircraft applications. A preliminary definition and assessment of a suitable multiprocessor architecture for such applications is developed

Some aspects of the efficient use of multiprocessor control systems

Computer technology, particularly at the circuit level, is fast approaching its physical limitations. As future needs for greater power from computing systems grows, increases in circuit switching speed (and thus instruction speed) will be unable to match these requirements. Greater power can also be obtained by incorporating several processing units into a single system. This ability to increase the performance of a system by the addition of processing units is one of the major advantages of multiprocessor systems. Four major characteristics of multiprocessor systems have been identified (28) which demonstrate their advantage. These are:- Throughput Flexibility Availability Reliability The additional throughput obtained from a multiprocessor has been mentioned above.. This increase in the power of the system can be obtained in a modular fashion with extra processors being added as greater processing needs arise. The addition of extra processors also has (in general) the desirable advantage of giving a smoother cost - performance curve ( 63). Flexibility is obtained from the increased ability to construct a system matching the user 'requirements at a given time without placing restrictions upon future expansion. With multiprocessor systems; the potential also exists of making greater use of the resources within the system. Availability and reliability are inter-related. Increased availability is achieved, in a well designed system, by ensuring that processing capabilities can be provided to the user even if one (or more) of the processing units has failed. The service provided, however, will probably be degraded due to the reduction in processing capacity. Increased reliability is obtained by the ability of the processing units to compensate for the failure of one of their number. This recovery may involve complex software checks and a consequent decrease in available power even when all the units are functioning