An interactive system at Harvey Wallbangers was measured...

Name: Problem 4, Chapter 6: Probability, Statistics, and Queuing Theory with Computer Science Applications, Second Edition (Computer Science and Scientific Computing)
Uploaded: 2021-12-15T17:41:38-08:00
Duration: 1 min 7 s
Channel: Hast Aggarwal
Description: An interactive system at Harvey Wallbangers was measured during a period in which 10 terminals were active with an average think time of 10 seconds. If each interaction required half a second of CPU processing and the CPU utilization was 40 percent, what was the average response time?

An interactive system at Harvey Wallbangers was measured during a period in which 10 terminals were active with an average think time of 10 seconds. If each interaction required half a second of CPU processing and the CPU utilization was 40 percent, what was the average response time?

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Key Concepts

Response Time Calculation

The response time is the interval from when a system starts processing a user request until the result is delivered. It is calculated in a closed-loop system by accounting for the CPU service demand modified by the system’s utilization, along with the effects of the user think time.

CPU Utilization and Service Demand

CPU utilization represents the fraction of time the CPU is busy processing user interactions, and service demand (or CPU service time) is the time required by the CPU to handle each interaction. These concepts are crucial in determining how effectively a system uses its processing resources.

Interactive Performance Modeling

This concept involves analyzing the performance of interactive computing systems where user actions and system responses occur in a closed-loop. It integrates metrics like service time, response time, and user think time to evaluate overall system performance.

Closed-Loop Throughput Law

This principle applies to systems where a fixed number of users cyclically interact with the system. It relates the number of users, their think time, and the response time to compute throughput, essentially using the relationship X = N/(R + Z), where N is the number of users, R is the response time, and Z is the think time.

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