process scheduling Flashcards
(29 cards)
CPU Burst
process execution consist of a cycle of CPU execution
Can the CPU serve another process if the currently served one is waiting.
True
what is a CPU scheduler
selects from the processes the memory that are ready for execution and allocates them in the CPU in one of them
new process
the process is being created
ready process
it is ready and waiting for execution by the CPU
running process
instruction is being executed in the CPU
waiting process
blocked waiting for the event to occur
terminated
the process is done
preemptive
the scheduler decides when the process stop run or resume
non-preemptive
once the CPU allocates a process and keeps executing until termination or the switching to waiting state
Job queue
Keeps all processes in the system
Ready queue
Keeps the processes in the main memory that are ready and waiting
Device queue
Processes are blocked due to unavailability of I/o devices constitute this queue
Process Control Block
OS data structure to keep track of all the processes
what is the PCB’s description
track execution state and location of a process
The OS allocates a new PCB with the creation of a process and place it in a state queue
de-allocate the PCB once the process is terminated
it’s stored in RAM
Process state
run, ready, Running, Waiting, terminated
Program Counter
indicates the address and the next instruction to be executed
CPU register
accumulator, register, stack pointer
CPU Scheduling information
process priority, scheduling queue, pointers
Dispatcher
allocates the CPU for the selected process by the scheduler
Dispatcher Latency
time to stop one process and start another
Context Switch
the CPU switch to another process and save the state of the old one and load the state of the new one
Burst time
total time taken for the process taken during execution
arrival time
when the process is in the ready state and ready for execution
