A novel time independent asynchronous communication protocol and its applications

This paper proposes a novel communications protocol called Time Independent Asynchronous (TIA) communications. This protocol constitutes a new category which has unique properties very useful in a variety of applications including embedded controller communications. The 2-wire TIA communications system proposed is implemented using software controlled IO. Analysis of this system shows that traditional Signal Transition Graphs (STGs) may fail to predict livelock and deadlock in software based systems. A modified form of STG called STG For Threads (STG-FT) is proposed to better model the behaviour of software driven systems and is shown to correctly detect livelock and deadlock that a normal STG model may miss. The performance of the new 2-wire TIA system is reported and livelock and deadlock properties found to match the STG-FT simulation. The new 2-wire TIA communication system has particular application to communications in products and industrial systems with low end microprocessors and any microprocessor that is heavily loaded with time critical applications

Statistical Reliability Estimation of Microprocessor-Based Systems

What is the probability that the execution state of a given microprocessor running a given application is correct, in a certain working environment with a given soft-error rate? Trying to answer this question using fault injection can be very expensive and time consuming. This paper proposes the baseline for a new methodology, based on microprocessor error probability profiling, that aims at estimating fault injection results without the need of a typical fault injection setup. The proposed methodology is based on two main ideas: a one-time fault-injection analysis of the microprocessor architecture to characterize the probability of successful execution of each of its instructions in presence of a soft-error, and a static and very fast analysis of the control and data flow of the target software application to compute its probability of success. The presented work goes beyond the dependability evaluation problem; it also has the potential to become the backbone for new tools able to help engineers to choose the best hardware and software architecture to structurally maximize the probability of a correct execution of the target softwar

Multi-microprocessor power system simulation

This thesis presents the results of research performed into the simulation of electrical power systems using a set of microprocessors operating in parallel , The uses and methods of simulation on analog and single processor computers are discussed as well as on multiple processor machines . It then considers various methods already used in the field of simulation for both the dynamic and network sets of equations in detail and the problems of using them on parallel processors . Several possible methods of parallel simulation are proposed and the best of these developed into a detailed algorithm for simulating both the dynamic and network portions of the power system .The different types of multiprocessor system are looked at , both in terms of physical configuration and the type of hardware used to implement the different types of system .The problems inherent in parallel computing are discussed and a form of multiprocessor, suitable for the simulation algorithm, is then developed taking these problems Into account. The hardware is developed using widely available hardware and the algorithm Is then Implemented upon this hardware .The results obtained using the simulator show that the proposed system provides a more economical solution, both in terms of the time taken in producing results and in the cost of the system, when compared with a conventional single processor computing system such as a mini computer

2-wire time independent asynchronous communications

Communications both to and between low end microprocessors represents a real cost in a number of industrial and consumer products. This thesis starts by examining the properties of protocols that help to minimize these expenses and comes to the conclusion that the derived set of properties define a new category of communications protocol : Time Independent Asynchronous ( TIA) communications. To show the utility of the TIA category we develop a novel TIA protocol that uses only 2-wires and general IO pins on each host. The protocol is analyzed using the Petri net based STG ( Signal Transition Graph) which is widely use to model asynchronous logic. It is shown that STGs do not accurately model the behavior of software driven systems and so a modified form called STG-FT ( STG For Threads) is developed to better model software systems. A simulator is created to take an STG-FT model and perform a full reachability tree analysis to prove correctness and analyze livelock and deadlock properties. The simulator can also examine the full reachability tree for every possible system state ( the cross product of all sub-system states), and analyze deadlock and livelock issues related to unexpected inputs and unusual situations. Reachability pruning algorithms are developed which decrease the search tree by a factor of approximately 250 million. The 2-wire protocol is implemented between a PC and an Atmel Tiny26 microprocessor, there is also a variant that works between microprocessors. Testing verifies the simulation results including an avoidable livelock condition with data throughput peaking at a useful 50 kilobits/second in both directions. The first practical application of 2-wire TIA is part of a novel debugger for the Atmel Tiny26 microprocessor. The approach can be extended to any microprocessor with general IO pins. TIA communications, developed in this thesis, is a serious contender whenever low end microprocessors must communicate with other processors. Consumer and industrial products may be able to achieve cost saving by using this new protocol

The development of a power system simulator using multiple microprocessors

Imperial Users onl

Exceeding Conservative Limits: A Consolidated Analysis on Modern Hardware Margins

Modern large-scale computing systems (data centers, supercomputers, cloud and edge setups and high-end cyber-physical systems) employ heterogeneous architectures that consist of multicore CPUs, general-purpose many-core GPUs, and programmable FPGAs. The effective utilization of these architectures poses several challenges, among which a primary one is power consumption. Voltage reduction is one of the most efficient methods to reduce power consumption of a chip. With the galloping adoption of hardware accelerators (i.e., GPUs and FPGAs) in large datacenters and other large-scale computing infrastructures, a comprehensive evaluation of the safe voltage reduction levels for each different chip can be employed for efficient reduction of the total power. We present a survey of recent studies in voltage margins reduction at the system level for modern CPUs, GPUs and FPGAs. The pessimistic voltage guardbands inserted by the silicon vendors can be exploited in all devices for significant power savings. On average, voltage reduction can reach 12% in multicore CPUs, 20% in manycore GPUs and 39% in FPGAs.Comment: Accepted for publication in IEEE Transactions on Device and Materials Reliabilit