Quiz: Linux Basics (Solution)

User Space, Kernel Space

• Kernel/user space: which of the following statements are true?

  Statement	True	False
  In kernel space there exists the concept of a process		n
  In user space there exists the concept of a process	y
  Interrupts are generally serviced in user space		n
  Interrupts are generally serviced in kernel space	y
  Scheduling of processes is done by the kernel	y
  Address spaces are implemented in user space		n

• How do programs communicate with the kernel? (One answer)

  Statement	True	False
  System calls	y
  Message queues		n
  IO ports		n
  Reverse interrupts		n

• File abstraction: which concepts are represented by file decriptors?

  Statement	True	False
  Files	y
  Network sockets	y
  Timers	y
  Serial/UART devices	y
  Memory		n
  The process stack		n

• The term “blocking” describes which behavior? (One answer)

  Statement	True	False
  A process can block another for communication purposes		n
  A process consumes no CPU time while it waits for an event to happen	y
  The kernel blocks access to network resources to enhance system security		n

Processes, Scheduling, and Virtual Memory

• Scheduling: which of the following statements are true?

  Statement	True	False
  A timeslice is the amount of time that a process can run until it is suspended in favor of other processes	y
  Fair scheduling ensures that network resources are evenly shared		n
  On a single-CPU machine, no process may enter an infinite loop - or else, the entire machine will come to a halt		n
  Fair scheduling ensures that every process gets its fair share of CPU resources	y
  The scheduler gives processes the illusion that each of them owns the CPU	y
  A context switch happens when one process enters a blocking system call	y

• Virtual Memory: which of the following statements are true?

  Statement	True	False
  A process can own all memory in the system		n
  The kernel is the owner of all memory in the system	y
  All processes share a single address space		n
  Each process in the system has its own address space	y
  An address space is three-dimensional		n

• Processes: which of the following statements are true?

  Statement	True	False
  A process is identified by its process ID	y
  A process is identified by its pthread context number		n
  Processes are arranged in a process hierarchy, starting at process 1	y
  A process may have multiple parents		n
  Every process has a parent process		n
  Every process except process 1 has a parent process	y

Dependencies