CS439: Principles of Computer Systems
Homework 2, Part 1
Due: 8:45a Friday, February 6, 2015 Part 1 of the
homeworks must be submitted electronically. Please refer to the
homework turnin instructions.
Open a terminal on a departmental Linux machine. After ensuring that you are in
a bash shell, use the time command to measure the time taken by a Linux
command that sends output to the screen (and maybe other things as well). You may use any Linux command
you like. For instance, a sample run might be (from your Project 0 directory):
Inspect the output. Explain the meaning of each line. Is the output as you
would expect? Why or why not? Include your command in your answer.
A typical hardware architecture provides an instruction called
return from interrupt, which is abbreviated by something like
rti. This instruction, which is usually only available while
the machine is running in kernel mode, switches the mode of operation
from kernel mode to user mode.
- Explain under what circumstances this instruction would be
used by the operating system.
- What happens if an application program executes
What differentiates a program, an
executable, and a process?
Given the following piece of code:
main(int argc, char** argv)
void forkThem(int n)
How many processes are created if the above piece of code is run?
Compare and contrast user threads and kernel threads.