Sharing memory in distributed systems

We propose an algorithm for simulating atomic registers, test-and-set, fetch-and-add, and read-modify-write registers in a message passing system. The algorithm is fault tolerant and works correctly in presence of up to (N/2) -1 node failures where N is the number of processors in the system. The high resilience of the algorithm is obtained by using randomized consensus algorithms and a robust communication primitive. The use of this primitive allows a processor to exchange local information with a majority of processors in a consistent way, and therefore to take decisions safely. The simulator makes it possible to translate algorithms for the shared memory model to that for the message passing model. With some minor modifications the algorithm can be used to robustly simulate shared queues, shared stacks, etc. (Abstract shortened with permission of author.)

Terrier: an embedded operating system using advanced types for safety

Operating systems software is fundamental to modern computer systems: all other applications are dependent upon the correct and timely provision of basic system services. At the same time, advances in programming languages and type theory have lead to the creation of functional programming languages with type systems that are designed to combine theorem proving with practical systems programming. The Terrier operating system project focuses on low-level systems programming in the context of a multi-core, real-time, embedded system, while taking advantage of a dependently typed programming language named ATS to improve reliability. Terrier is a new point in the design space for an operating system, one that leans heavily on an associated programming language, ATS, to provide safety that has traditionally been in the scope of hardware protection and kernel privilege. Terrier tries to have far fewer abstractions between program and hardware. The purpose of Terrier is to put programs as much in contact with the real hardware, real memory, and real timing constraints as possible, while still retaining the ability to multiplex programs and provide for a reasonable level of safety through static analysis

Notes on Theory of Distributed Systems

Notes for the Yale course CPSC 465/565 Theory of Distributed Systems