Labs 3-4: Resources and Capabilities

Steps for this Lab:

1. Review Program 2.13 in Hartley's text. This program is available as file ~walker/parallel/sr/book/Program_2.13
   Copy this program to your account, giving it the new name lab3a.sr
   Compile and run the program.
   Explain how the program works:
   • Write a paragraph explaining what a resource is and how it is defined.
   • Explain the purpose of each of the following statements:

     
     var fac_cap : cap factorial
     fac_cap := create factorial
     

   • Explain what happens when the statement
     write(n, "factorial is", fac_cap.fact(n))
     is executed.

2. Copy ~walker/parallel/sr/book/Program_2.15 to your account as lab3b.sr.
   Compile and run the program and explain how it works:
   • Annotate each main element of the program, describing its function.
   • Trace the running of this program.
     In particular, indicate what happens to generate each line of output.

3. Copy ~walker/parallel/sr/examples/matrix3 to your account as matrix3
   (This is the compiled form of ~walker/parallel/sr/examples/matrix3.sr .)
   Using the submit command, record the output of the command matrix3 3 4 5
   • Explain the purpose of the getarg statements.
   • What is the purpose of the reply statement? (To get started, you may want to review page 43 of Hartley's text.)
   • Explain the purpose of the statement

     
        fa id := 1 to num_proc ->
           create multiply_block(id, block_size)
        af
     

   • What does a nap statement do?
   • Explain the sequence of events that occured in producing a sample.

4. Copy ~walker/parallel/sr/examples/matrix4.sr to your account as matrix4.sr
   • Explain the purpose of the statements:

     
        const max_cap := 10          /* maximum number of processes possible */
        var machine_cap[1:max_cap]: cap vm
     
           #create new processes
        fa i := 1 to num_proc ->
            machine_cap[i] := create vm ()
        af
     

   • Compile and run the program in its present form (with the multiple processes line commented out).
     Explain the purpose of the lines:

     
        fa id := 1 to num_proc ->
           create multiply_block(id, block_size) 
                                     /* run as threads of same process */
        af
     

     How do these lines help generate the output?
   • Comment out the line
     create multiply_block(id, block_size)
     and include the line
     create multiply_block(id, block_size) on machine_cap[id]
     Now compile and run the program again. Explain the purpose of the lines:

     
        fa id := 1 to num_proc ->
           create multiply_block(id, block_size) on machine_cap[id]
                                     /* run as multiple processes */
        af
     

     How do these lines help generate the output?
     Clarify the difference between this version and the previous.

5. Review the version of your fractals program that defines a separate process for a block of rows. Rewrite this version so that the results array is stored as a separate global resource, and so that the process construct is moved to a separate resource. Then use a create statement to create separate threads to do this work.

Work to be turned in:

For Lab 3:

• Your explanation and/or annotations for parts 1, 2, and 3.
• A copy of your output for part 3.

For Lab 4:

• Your explanation for part 4.
• A copy of your revised program for part 5.

This document is available on the World Wide Web as

http://www.math.grin.edu/~walker/courses/295/lab3.html