Flashcards
Blandat - operativsystem
Cards in this deck (26)
- 1concurrent programmingConcurrent computing is a form of computing in which several computations are executed during overlapping time periods—concurrently—instead of sequentially
- 2Definition of a Program, executable. process*A set of human readable instruktions. A passive entity
* A compiled form of a program, machine instructions that a computer can load and execute
* A program loaded into memory, executing or waiting. Active. Needs resources. - 3Dual-mode operationDifferentiate between user mode and kernel mode
- 4ExceptionsTo handle errors. Internal and synchronous . Ex: overflow, div by 0.
- 5InterruptsUsed to notify the CPU of external events. For example: keypress on keyboard
- 6Operating system structureLibrary functions > system calls > Kernel > hardware
- 7Memory; stack,heap,dataStack: temp data such as function parameters, local variables
Heap: dynamically allocated data during runtime
Data: global variabels etc - 8State diagram - processes
- 9Goal of multiprogrammingto have some process running at all times, maximise CPU utilization
- 10file descriptorsan abstract indicator used to acess file or other input/output resources
- 11Scheduling Dispatchergives control of the CPU to the process selected by a short-term scheduler. This includes;
*switching context
*switching to user mode - 12Dispatch latencytime it takes for the dispatch to stop one process and start another
- 13batch processCan be either I/O bound or CPU bound. Do not need user interaction, often run in the background
- 14Classification of processes*I/O bound
*CPU bound
*interactive
*batch
*realtime - 15Real-time processStrong scheduling requirements - should never be blocked
- 16Convoy effectWhen long processes are scheduled before short -> average wait time increases
- 17RR vs SJFRR have higher turnaround time than SJF, but better response time
- 18Response timetime from request/arrival until first response
- 19Multilevel queuesUsed when processes can be classified into groups based on properties like type, CPU time, I/O access
- 20How is scheduling done between queues in multilevel queue scheduling?*Fixed prio queue -> starvation
*Time slice: each queue gets a certain amount of CPU time - 21What does time slicinging meanA foreground process can be given 80% of the CPU time, for RR scheduling. And 20% for background with FCFS
- 22what is priority inversion?A higher priority task is preempted by a lower
- 23How can you detect deadlock?*Single instance of resource typ -> wait for graph!
* Periodically invoke an algorithm which searches for circles in the graph - 24How can you recover from deadlock?*abort one or more processes to break circular wait
*Preempt processes! - 25What are the different edges in RAG?*claim edge
*request edge
*assignment edge - 26When can you request a resource in RAG?only if request->assignment edge doesnt result in the formation of a cycle
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- Operating systems Flashcards on Blandat - operativsystem, created by Emma Tysk on 14/03/2017.
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- Emma Tysk
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