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to 3013 Home Page Due date: Tuesday, October 11th by 11:59pm
This project is designed to give you some experience in the use of some of the memory management tools.
You are to evaluate memory use in conjunction with forked processes and spawned threads. This evaluation proceeds in several steps with questions for each step.
Write a program that declares a two-dimensional array of 4096x4096
bytes. Make one pass through the entire array, going across the
columns and setting values, and then print information about the page
faults using getrusage(). Report the minor (soft) and
major (hard) page faults separately. Make a second pass through the
same array and again, print page fault information. Remember that the
statistics for getrusage() are not reset each call but
rather accumulate over the life of a process.
Question 1: Why did you obtain many minor page faults the first time through the array? Did you obtain more minor or major page faults for the second pass? Why or why not?
Create a similar program that goes down the rows first, causing the elements to be accessed a column at a time rather than a row at a time. Compile and re-run the previous test.
Question 2: How do your results differ from the previous results? Why are they the same or different?
Create a new program that creates a new process via a
fork() call before walking through the array. Both
processes then walk through the array as in the first step.
Question 3: How do your results differ from the initial results? Why are they the same or different?
Create a similar program that creates a new thread via a
pthread_create() call before walking through the array.
Both threads then walk through the array as in the first step. Don't
worry if there are race conditions here.
Question 4: How do your results differ from the previous results with fork()? Why are they the same or different?
Create a test program that contains a recursive function with
a single argument, the number of times to recurse. The function
should contain a local array of 4 Kbytes. Before recursing, the
function should set elements in the array so the page is actually
faulted into memory. Test your program compared with values
returned by the getrlimit() call.
Question 5: Are the results consistent with the resource
limit? Use the system call setrlimit() to increase the
stack and explore further in your answer.
The following system calls might be useful:
fork() -- to create a new process.
getrusage(), getrlimit(), setrlimit() -- to get/set information about resource utilization and limits.
pthread_create() -- to create a new thread.
You might consider trying your code with a while()
loop rather than for() loop to see if there is a difference
due to compiler optimizations.
You might try allocating different sized memory chunks and perhaps doing only single row/single column initialization and see if there are differences.
You must hand in the following:
The turnin (/cs/bin/turnin) for proj4 is "proj4".
When turnin, also include file "group.txt" which contains the
following:
group_name
login_name1 last_name1, first_name1
login_name2 last_name2, first_name2
...
Also, before you turnin tar up (with gzip) your files. For example:
mkdir proj4
cp * proj4 /* copy all your files to submit to proj1 directory */
tar czf proj4.tgz proj1
then:
scp proj4.tgz login_name@ccc:~/
ssh login_name@ccc /* will ask your ccc passwd */
/cs/bin/turnin submit cs3013 proj4 proj4.tgz
Send all project questions to the cs3013-staff at cs.wpi.edu mailing list.
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