Quantum Length Analysis

# Quantum Length Analysis - Quantum Length Analysis What is...

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Quantum Length Analysis What is the impact of quantum length? Assume T=10ms. Process Burst Time p1 20ms p2 1ms p3 1ms 1 10 P3 P1 P2 Average completion time = (11+12+22)/3=15ms 1 P1 10

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Quantum Length Analysis What if we choose a smaller quantum length?Assume T=1ms. Process Burst Time p1 20ms p2 1ms p3 1ms 1 1 P3 P1 P2 Average completion time = (2+3+22)/3=9ms 1 P1 T=1ms P1 1 1 P1 P1 1 1
Quantum Length Analysis The shorter the quantum, the shorter the average completion time. Based on this we could make the quantum time very small to achieve faster response time. What is the catch? We are not considering that context switch takes time. We have to consider the context switch overhead.

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Context Switch Overhead The context switch overhead is the time it takes to do a context switch as a portion of the quantum time. Xoverhd% = 100*X/T where Xoverhd% = Context Switch Overhead X = Context Switch Time T = Quantum Time.
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## This note was uploaded on 01/30/2012 for the course CS 354 taught by Professor Staff during the Fall '08 term at Purdue.

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Quantum Length Analysis - Quantum Length Analysis What is...

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