Upload a pdf file containing your solutions to the problems below to Learning Suite before 11:00pm on the assigned date.

1. Problem 6.26

2. Problem 6.27

3. Problem 6.29

4. Problem 6.38

5. Problem 6.39

6. Problem 424-7:
   Click here to get a tar file with some source code that you just analyzed for problems 6.38 and 6.39 from the text. Let's see what we can learn from running similar code on a real machine. Typing "make" in the cacheperf directory should produce a "cacheperf" executable that you can run. Look through the source code of "cacheperf.c" to see what it does. Note that, for each of the three code portions measured, the program outputs both raw cycle counts and summaries of relative run time, where the base length is the run time with a warm cache and good locality. The results obtained by running the program should give us insight into (a) performance differences between cold and warm caches, and (b) performance differences between access patterns with good and poor locality. You should recompile and run the program from a wide variety of SQSIZE values (in "cacheperf.c"). Include one or more tables of results, and write a paragraph that answers the questions below, along with anything else you observed that is noteworthy.
   • Unlike most other measurement code we've used this semester, the results this program reports are based on single measurements. (It would be tricky to repeat cold cache performance measures.) How consistent are the results of this program if you run it many times?
   • For what values of SQSIZE is the difference in performance the greatest between having a warm cache and a cold cache? Explain your results.
   • For what values of SQSIZE is the difference in performance the greatest between reference sequences with good and poor locality? Explain your results.
   • How do your results change if you edit the Makefile and change the optimization level used to compile cacheperf.c to "-O3"? Explain the differences you observe. (You might glance at the assembly output of the inner loops to see how the compiler optimized the resulting instructions.)

Clarifications

Problem 424-7: No source code need be included in your submission. Think through the results you report until you feel that you can explain them.

Apparently you have to make a slight modification to the code to get it to work on a Mac. In the timer.c file (included in cacheperf.tar), insert the word "volatile" immediately after "asm" in the access_counter function. With this fix, it is reported that you can use higher levels of optimization, contrary to the comments in timer.c.