'CSC521' Category

  • DNS and Eventual Consistency

    December 9, 2016

    Overview The internet Domain Name System (DNS) is an distributed, highly available database of facts, called Resource Records (RR) relevant to the operation of the Internet. Created by Paul Mockapetris in 1983, it is a harbinger for the highly available, distributed databases of today. The DNS system answers queries about the collection of RR’s by […]

  • Amazon Dynamo

    November 20, 2016

    There is an excellent paper on Dynamo appearing in SOSP 2007. These notes are a boil-down of that paper, and perhaps casting this particular technology into a fable about an entire approach to persistence — that which emphases availability with reasonable consistency properties, if not strict consistency. Modern persistence needs to scale to tremendous database […]

  • Interprocess Communication

    September 28, 2016

    The process idealization provides an environment. For the process to affect the world, processes must work together exchanging information and the timing of events. Process often exchange information through files, as well as having the process exchange information with itself, displaced in time, when information is placed in a file for retrieval later, or when […]

  • Process Permissions

    September 25, 2016

    The operating system enforces a system of rights and permissions. Rights and permissions refer to permitted or restricted actions that one category of entity, the subject, performs on another category of entity, the object. Intuitively, the subject is a user and the object is something over which the user has jurisdiction. The operating system models […]

  • The Thread Abstraction

    September 23, 2016

    A process is a data context and one or more threads that run in that context. A thread is the ability or the actuality of executing a sequence of instructions. The computer instructions are loaded into memory is a part of the context. A thread is the running or potential running of that code. A […]

  • The Process Abstraction

    September 22, 2016

    The subject of operating systems is the ideation and mechanisms of support of software abstractions — almost exclusively those abstractions that enable a user to run computer programs. The abstraction most closely associated with a program is the process. A process is best thought of as a data container for the collected information needed to […]

  • Microkernels

    September 7, 2016

    Microkernel Architecture The Linux kernel employs a traditional approach to operating systems, where the kernel is has no generalized structure. The kernel is thought through thoroughly by the master architect as a single work of code. Starting with the Mach operating system, there has been an attempt to rationalize the kernel around a message passing […]

  • Virtual Machines and Hypervisors

    September 4, 2016

    Virtual Machines and Hypervisors For reasons of efficiency or convenience, it is desirable that an entire operating system be run as a guest of another operating system. The host operating system creates a software entity that models the hardware of a physical machine, called the virtual machine (VM), and presents this to the guest operating […]

  • Producer Consumer problem

    October 16, 2014

    Produced Consumer problem A classic problem in process synchronization is the case of one or more producers that add items to a queue, or any sort of storage bucket, and one or more consumers that take items from the queue or bucket. The synchronization is on both the critical section of the mechanics of adding […]

  • A new theory of processes

    September 20, 2014

    A process is a container in that it collects context under an authority and consistency, and it is a referent in that it can be the target of scheduling, of signals and communication, and of hierarchies and networks of other processes. A process is an object for a conceptually distinct task. As an object, it […]

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