Queuing Models

• Service time (Average, distribution)
• Arrival Rate (Average, distribution)
• Single/Multiple Queue or Server.

    
  Figure: Single / Multiple Queue or Server
  

• Measures
  • Response time / Throughput.
  • Utilization. High utilization leads to large response times.
• Open Queuing System v/s Closed Queuing Systems : Arrival rate drops as the response time increases. Note that there are fixed number of clients.
• Parameters
  • Sevice time / Distribution of various queues.
  • Arrival rate.
• Examples : CPU queue, disk queue, log queues, N/W queue
• Queuing models are good for transaction processing systems.
• Transaction go from queue to queue - i.e. CPU to disk to CPU to Lock to CPU ....