COP4600 Exam 1 With Correct Answers

COP4600 Exam 1 ubiquitous computing - ANS many computers, one use Memory partition in multiprogramming systems - ANS single partition for OS, separate partitions for jobs Registers - ANS fastest memory; as fast as CPU Cache - ANS slower than registers, faster than RAM RAM - ANS faster than disk, slower than cache/registers Disk - ANS slower than other memory solutions; SSD faster than HDD 4 parts of a process - ANS Text, data, heap (grows up), stack (grows down) Heap - ANS used for dynamic allocation of data Stack - ANS used for local variables (local functions are pushed onto and off of this) Goals of OS - ANS Define and implement abstractions Hide the hardware Execute programs + ensure isolation Manage resources OS core guidelines - ANS should consistently implement policies AND separate policies and mechanisms Layered - ANS type of OS design that contains layers, where each layer can only use the layers beneath it Microkernel - ANS type of OS design that handles requests from user space and sends them to services Virtualization - ANS uses a hypervisor to interact with hardware on the host machine Container - ANS uses an engine, containing abstractions for the hardware on the host machine AND the guest OS Pseudoparallelism - ANS each process uses CPU in turn through context switching; state of processes swapped is stored on registers Process table (PCB) - ANS contains information about processes in the OS Scheduler - ANS handles interrupts and process/thread scheduling Context switching - ANS occurs when a process yields the CPU or is interrupted; state of process is saved on registers Signal - ANS causes software interrupts IO - ANS causes hardware interrupts Direct messaging - ANS two processes explicitly communicate with each other using send() and receive() Indirect messaging - ANS processes communicate with each other using a mailbox system Intent - ANS form of process messaging used on Android; can be explicit (specifying who should receive) or implicit (let OS decide who should receive) Race condition - ANS Issue occurring when using shared memory where two processes are accessing the same memory using write/read Critical region - ANS Segment of code where access to shared memory is found Kernel-space threads - ANS Uses a single thread table in kernel-space alongside the process table User-space threads - ANS Uses a thread table inside of each process; not visible to the kernel Peterson's solution - ANS a way of ensuring mutual exclusion for two processes without using mutexes or semaphores using busy waiting TSL - ANS uses busy waiting with registers to ensure mutual exclusion Producer-Consumer problem - ANS problem which illustrates how two or more processes could get stuck in a busy waiting sequence through messaging in a shared finite buffer, resulting in deadlock Round-robin - ANS scheduling policy that gives each process a quantum in which in can use the CPU Priority - ANS scheduling policy that uses separate queues based on a process's priority; scheduling policy within each queue can differ Shortest job next - ANS scheduling policy that selects the shortest process and allows it to finish entirely; prone to starvation