Tietojenkäsittelytieteen laitos

Perf. Eval., Homework 2 (due 20.3.2002)

1. Make a copy of the Dhrystone benchmark directory (http://www.cs.Helsinki.FI/~kerola/ska/dhrystone/) and use Dhrystone to measure the speed of three systems with different processors. Possible systems include hydra, kruuna, stubben-n ja tauvo-n.
   1. What can you say about the speed of these three machines, based on your test.
   2. What types of error sources did your test have?
   3. What system would you recommend based on your test and why?
   4. What system properties does the Dhrystone benchmark specifically test?
   
   You can find more information on Dhrystone, for example, in R.P. Weicker article An Overview of Common Benchmarks, IEEE Computer, December 1990. You can find a pdp copy  in the TKTL electronic library (licenced for TKTL students and researchers) or in paper form in the course folder in A412.
   
   
2. One measure for the speed of computers is MIPS.
   1. What does MIPS mean?
   2. How would you measure the MIPS count for your own computer?
   3. Give at least three reasons why MIPS is a bad measure for performance.
   4. Why is MIPS a good measure for performance?
      
      
3. You are in charge when your grocery retail employer is going to purchase a new cashier register system, which will take care of the inventory at the same time. How would you estimate the performance requirements for it? If you would need to build a performance model for this system, would it be closed or open? Why?
   
   
4. Assume that we have a single class closed model.
   What effect would increased think time (Z) have for system response time (R)?
   Would it increase or decrease? Why?

   Assume for now, that we have two job classes. Come up with a situation where speeding up some resource would result in slowing down (response time get bigger) one (or both) of the job classes? Explain why this occurs.
   
   

5. [2 htp] Assume that we want to evaluate a new cell phone for its performance characteristics. Concentrate on the hand-held unit. We have decided that we need a performance model for the phone.
   1. Is it a closed model, open model, or mixed model?
   2. Is it single class model or multiple class model? What are the job classes?
   3. What resources are there in the model? Are they queueing resources or passive resources? HW or SW?
   4. How would you incorporate rest of the cell-phone infrastructure (network, other phones, routing, various data bases, etc.) in the model?
   5. How do you determine HW/SW parameters for your model?
   6. How would you solve your model?
   7. Are there any simplifications that you might do to make your model easier to solve?