FOR FREE CONTENT
- 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
Highest Response Ratio Next (HRRN):
The HRRN policy computes the response ratios of all processes in the system according to the response ratio and selects the process with the highest response ratio:
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R = Response ratio
W = Time spent waiting for the processor
S = Expected service time (Burst Time)
Mode: Non Preemptive
# HRRN not only favors shorter jobs but also limits the waiting time of longer jobs.
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Gantt Chart
Initially, P0 gets the CPU and completes till the end (Because HRRN is non-preemptive), after completion of P0, only P1 in the completes ready queue then complete P1 till the end.
Gantt Chart; Scheduling
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Ready Queue
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At time 10 after completion of P1, all the remaining processes are in the Ready queue (ready to execute).
Now we calculate the Response Rate of P2, P3, and P4.
Now at this moment Waiting Time = First Response – Arrival Time
[As we know at non-preemptive Waiting Time = Response Time]
P2 = 10 – 5 = 5, P3 = 10 – 6 = 4, P4 = 10 – 8 = 2
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Now, RR(P4) = 2 is larger so, P4 will get CPU first.
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# Again after completion of P4 at 12, calculate the Response Ratio of the remaining processes to decide which one goes first.
Waiting time:
P2 = 12 - 5 = 7, P3 = 12 - 6 = 6
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Now, the Response Ratio (2.2) of P3 is highest so, P3 will schedule first then remaining process P2 will schedule.
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Now we calculate Turn Around Time (TAT) and Waiting Time (WT) using the following formula:
TAT = CT - AT, WT = TAT – BT
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HRRN process schedule not only as per shortest job also see another criterion which process wait for a long time.
