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- Introduction: OS
- Booting Process
- Command Interpreter
- Dual mode of operation
- System Calls
- Difference between system call and library call
- Interrupt and Trap
- Introduction
- Scheduling Criteria, Terms and Concepts
- Different Type Scheduling Algorithms
- Longest Job First
- Longest Remaining Time First
- Highest Response Ratio Next (HRRN)
- Priority Scheduling
- Least Completed Next (LCN) Scheduling
- Multi-Level Queue Scheduling
- Multilevel Feedback Queue Scheduling
- Guaranteed Scheduling
- Fair Share Scheduling
- Lottery Scheduling
- Multi-Processor Scheduling
- Deadline Scheduling
- Rate-Monotonic Scheduling
- POSIX Real-Time Scheduling
- Priority Inversion
- Proportional Share Scheduling
- Comparison table of Scheduling Algorithm
- Algorithm Evaluation for Scheduling
- Important concept of MM
- Memory Representation as Address
- Memory layout for a Process
- Logical and Physical Address Space
- Necessity of Memory Management
- Introduction
- Concept of Non-contiguous memory allocation
- Basic concept of Paging
- Address Translation
- Process of Paging Method
- Calculation of Offset for paging
- Calculation of Logical Address Bit and number of Pages
- Calculation of Physical Address Bit and number of Frames
- Calculation of Page Table Size
- Organization of MMU
- Why Page size power of 2
- Paging Address Calculation: example1
- Paging Numeric Problem: Example2
- Paging Address Calculation: Example3
- Paging Address Calculation: Question1
- Some Important Question 2
- Paging Address Translation: Question3
- UGC NET Paging Question
- GATE Paging Question
- Number of information at Page Entry
- Exams Question on Page Entry Information
- Exam Question: Page Entry Information
- Calculates Page Table Entry Size
- Calculates Page Size
- Calculation of Optimal Page Size
- Question on Optimal Page Size
- Hashed Page Table with Example
- Inverted Page Table with Gate Question
- Question on Inverted Page Table
- Multi-Level Paging
- Multi-level paging: Example1
- Multi-level paging: Example2
- Allocation of Frames
- Subject Mock
Quick Fit and 50 percent rule
5) Quick fit
Yet another allocation algorithm is quick fit, which maintains separate lists for some of the more common sizes frequently requested. So, it maintains a separate linked list for this frequently request process size.
For example, it might have a table within entries, in which the first entry is a pointer to the head of a list of 4-MB holes, the second entry is a pointer to a list of 8-MB holes, the third entry a pointer to 12-MBholes, and so on. Holes of, say, 21-MB, could be put either on the 20-MB list or on a special list of odd-sized holes.
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But maintain the separated linked list for frequently use process size is not a good approach because de-allocation might have a big problem. It is quick but not at all efficient.
So, among all first fit is the best one, and most widely used is first fit.
50 percent rule:
Depending on the total amount of memory storage and the average process size, external fragmentation may be a minor or a major problem. Statistical analysis of the first fit, for instance, reveals that, even with some optimization, the given N allocated blocks, another 0.5 N blocks will be lost to fragmentation. That is, one-third of memory may be unusable. This property is known as the 50-percent rule.
