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CS350 (1)
Lecture

Review Tables In the course there are some comparison between different address translations, scheduling strategies , and others. I have made a couple of tables that compare them ( advantages , disadvantages , comments )


Department
Computer Science
Course Code
CS350
Professor
David Taylor

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CS350 Review
Address Translation
Features/Types
Dynamic relocation
Paging
Segmentation
Physical memory
management
OS must allocate/de-allocate
variable sized chunks of
physical memory
Simple physical memory
management
Simple physical memory
management
Problems
External fragmentation
(wasted, unallocated space)
Internal fragmentation
(wasted, allocated space)
Internal fragmentation
Requirements
Relocation register, value for
each process
Page table for each process
Have to make it be understood
by the application and directly
supported by MMU & OS
Translation
Each virtual address space
corresponds to a contiguous
range of physical addresses
Virtual address space need not
be physically contiguous in
physical space
Requires physically contiguous
allocation of segments
Thread Scheduling
Features/Types
First come fist
served (FCFS)
Round Robin
Shortest
remaining time
first (SRTF)
High Response
Ratio Next (HRRN)
Multi level
feedback queue
kind
Non-preemptive
preemptive
preemptive
Non-preemptive
preemptive
Benefits
Simple
Fair - give fixed
time for each
thread to run
Minimizes average
waiting time
Make use of burst
time and waiting
time
Make use of
prioritization and
burst length
problems
No good burst
estimate
No good burst
estimate
requirements
Maintain a queue
Mechanism to
calculate quantum
time
Requires
knowledge of CPU
burst lengths
Requires
knowledge of CPU
burst lengths and
waiting time
Maintain several
ready queues
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