Test #2 Flashcards
TurnAround
Complete - Arrive
Wait
TurnAround - CPU Needs
NTAT
TurnAround / CPU Needs
Response Time
Enter (input) to feedback
throughput
how many jobs over a period of time
CPU Scheduler
Allocate CPU time to different processes in a fair way based on scheduling algorithm in use
Short-Term Scheduler
selects which process from ready queue should be allocated for execution
Dispatcher
Actually performs the context switch
Context Switch
saving state of currently running process and loading the state of the next process
CPU Burst
When a process is actively using the CPU
I/O Burst
When a process is performing I/O Operations
Scheduling Criteria Maximize and Minimize
Maximize:
- CPU Utilization
- Throughput
Minimize:
- TAT
- Waiting Time
- Response Time
Processor Sharing
Round Robin as Time slice approaches zero; NOT IDEAL: too much overhead when context switching
Round Robin
FCFS with Time Slice
Starvation
starved from getting CPU
Priority scheduling
prioritizes processes based on assigned priority
Aging
Increases the priority of waiting processes to prevent them from starving
Mutex
When multiple processes want accesss to shared memory, you need to have Mutually Exclusive access to prevent lost updates
Critical Section
Part of code dealing with the shared resource
Race Condition
Who goes first when multiple processes want access to a shared resource
Lost Update
Two processes make change to shared memory at the same time, one of the new values is lost
Busy Wait Solutions
Semaphores
TSL
Test Set Lock: Early solution to shared memory, bad because busy wait
Semaphore
Abstract data type with an integer s and two operations P() and V()
