Notes on fixed partitioning of memory by the operating system.

1. Fixed
Partitioning
of Memory
ACS 331

2. PROPOSAL
OUTLINE
KEY DISCUSSION
POINTS
Definitions
Contiguous Technique
Algorithms in Partitioning
Advantages & Disadvantages
Conclusion
Important Things to
Remember

3. INTRODUCTION
MEMORY MANAGEMENT
Memory Management is the function
responsible for allocating and
managing computer’s main memory.
Memory Management function keeps
track of the status of each memory
location, either allocated or free to
ensure effective and efficient use of
Primary Memory.

4. THINK ABOUT IT
Many a man fails to become a
thinker for the sole reason
that his memory is too good.
FRIEDRICH WILHELM NIETZSCHE

5. CONTIGUOUS
TECHNIQUE
FIXED(STATIC) PARTITIONING
In this technique, the main memory is
divided into partitions of equal or
different sizes.
The operating system always resides in
the first partition while the other
partitions can be used to store user
processes.
The partitions cannot overlap.

6. Internal Fragmentation
is the amount of
unused memory space after allocation

7. PLACEMENT ALGORITHMS
First Fit : Allocate the first free block that is large enough for the new
process.
Best Fit : Allocate the smallest block among those that are large
enough for the new process. The OS has to search the entire list, or it
can keep it sorted and stop when it hits an entry which has a size larger
than the size of new process. This algorithm produces the smallest left
over block. However, it requires more time for searching all the list or
sorting it
Worst Fit : Allocate the largest block among those that are large
enough for the new process. Again a search of the entire list or sorting
it is needed. This algorithm produces the largest over block.

8. Easy to implement:
Algorithms needed to implement
Fixed Partitioning are easy to
implement. It simply requires
putting a process into certain
partition without focusing on the
emergence of Internal and External
Fragmentation.
Little OS overhead:
Processing of Fixed Partitioning
require lesser excess and indirect
computational power..
ADVANTAGES

9. DISADVANTAGES
Internal Fragmentation:
Main memory use is inefficient. Any
program, no matter how small, occupies
an entire partition. This can cause
internal fragmentation.
External Fragmentation:
The total unused space of various
partitions cannot be used to load the
processes even though there is space
available but not in the contiguous form
(as spanning is not allowed).
Limit process size:
Process of size greater than size of
partition in Main Memory cannot be
accommodated. Partition size cannot
be varied according to the size of
incoming process’s size. Hence, process
size of 32MB in above stated example is
invalid.

10. CRITICAL POINTS
CONTIGUOUS TECHNIQUE
PLACEMENT ALGORITHMS
ADVANTAGES AND
DISADVANTAGES

11. REFERENCES
Principles of Modern Operating Systems
By José M. Garrido, Richard Schlesinger (Pg 249)
https://www.geeksforgeeks.org/fixed-or-static-
partitioning-in-operating-system/
http://examradar.com/memory-management-2/
https://www.javatpoint.com/os-fixed-partitioning

12. THANK YOU !