PPT Slide
SCHEDULING POLICIES
FIFO
Round Robin
SPN (SPF)*
SRT*
HRRN*
Feedback
Fair share
selection function
max {w}
constant, time quantum
min {s}
min {s-e}
max
{(w+s)/s}
min{w}, using queues
f {base, CPU, GCPU}
decision mode
Non preemptive
preemptive
Non preemptive
preemptive
Non preemptive
preemptive
preemptive
throughput
no emphasis
low if quantum too small
high
high
high
no emphasis
no emphasis
response time
high if large variance
good for short processes
good for short processes
good
good
no emphasis
no emphasis
overhead
minimum
low
can be high
can be high
can be high
can be high
can be high
effect
penalizes: short and I/O bound
fair treatment
penalize long processes
penalize long processes
good balance
may favor I/O bound
favor highest priorities
starvation
No
No
Possible
Possible
No
Possible
No
* require knowledge of process length
w = time in the system; e = time executing; s = total time required
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