Operating Systems 2015F: Assignment 5

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  1. Within a UNIX filesystem, one inode can be referred to by many different pathnames (filenames). What is another term for these names?
    • hard links
    • symbolic links
    • URLs
    • all of the above
  2. A modern monolithic operating system kernel typically implements
    • scheduling \& address space management
    • some device drivers
    • a TCP/IP stack
    • All of the above
  3. An OS that is based upon a microkernel architecture will typically:
    • have most device drivers and filesystem code run within separate userspace processes
    • have most OS code run in CPU supervisor mode
    • support loadable kernel modules
    • All of the above
  4. A typical executing application is best described as a:
    • kernel
    • process
    • thread
    • system call
  5. When a running program X requests data from a file F whose contents are on disk, the OS will:
    • save X's current state
    • schedule a disk request for F's data blocks
    • load the state of another ready-to-run program Y (which may be X)
    • All of the above
  6. When a regular process is running on a single-CPU system, all of the following are true except:
    • The kernel is running.
    • Disks can be writing data to memory.
    • The CPU will generate an exception (software interrupt) if certain addresses are accessed.
    • The CPU is in user mode.
  7. Modern virtual memory systems:
    • Logically divide RAM into fixed-sized chunks
    • Store portions of processes on disk
    • Allocate a logical address space to each process that is distinct from the physical memory map
    • All of the above
  8. The ``dirty bit in a page table entry indicates that:
    • A security violation has occurred
    • The corresponding page has been accessed.
    • The corresponding page has been modified.
    • The corresponding page is shared between multiple processes.
  9. An inode contains all of the following except:
    • user ID
    • filename
    • time of last data modification
    • link count
  10. When checking the consistency of a filesystem (e.g. after a loss of power), all of the following must be checked except:
    • inode reference counts
    • pointers to data blocks (in inodes or indirect blocks)
    • contents of data blocks of regular files
    • block free list
  11. If a system automatically boots into a defective kernel (e.g., one that crashes on startup), you can recover the system by:
    • Select a different kernel in the bootloader
    • Perform a soft reboot of the system
    • Perform a hard reboot of the system
    • Press Alt-SysRq-R
  12. Virtual memory is prohibitively expensive on a system that lacks a TLB because
    • Every memory access then requires a system call.
    • The page table has to be checked on every memory access
    • The process table has to be updated on every tick interval.
    • None of the above

Solutions

  1. Within a UNIX filesystem, one inode can be referred to by many different pathnames (filenames). What is another term for these names?
    • hard links
    • symbolic links
    • URLs
    • all of the above
  2. A modern monolithic operating system kernel typically implements
    • scheduling \& address space management
    • some device drivers
    • a TCP/IP stack
    • All of the above
  3. An OS that is based upon a microkernel architecture will typically:
    • have most device drivers and filesystem code run within separate userspace processes
    • have most OS code run in CPU supervisor mode
    • support loadable kernel modules
    • All of the above
  4. A typical executing application is best described as a:
    • kernel
    • process
    • thread
    • system call
  5. When a running program X requests data from a file F whose contents are on disk, the OS will:
    • save X's current state
    • schedule a disk request for F's data blocks
    • load the state of another ready-to-run program Y (which may be X)
    • All of the above
  6. When a regular process is running on a single-CPU system, all of the following are true except:
    • The kernel is running.
    • Disks can be writing data to memory.
    • The CPU will generate an exception (software interrupt) if certain addresses are accessed.
    • The CPU is in user mode.
  7. Modern virtual memory systems:
    • Logically divide RAM into fixed-sized chunks
    • Store portions of processes on disk
    • Allocate a logical address space to each process that is distinct from the physical memory map
    • All of the above
  8. The ``dirty bit in a page table entry indicates that:
    • A security violation has occurred
    • The corresponding page has been accessed.
    • The corresponding page has been modified.
    • The corresponding page is shared between multiple processes.
  9. An inode contains all of the following except:
    • user ID
    • filename
    • time of last data modification
    • link count
  10. When checking the consistency of a filesystem (e.g. after a loss of power), all of the following must be checked except:
    • inode reference counts
    • pointers to data blocks (in inodes or indirect blocks)
    • contents of data blocks of regular files
    • block free list
  11. If a system automatically boots into a defective kernel (e.g., one that crashes on startup), you can recover the system by:
    • Select a different kernel in the bootloader
    • Perform a soft reboot of the system
    • Perform a hard reboot of the system
    • Press Alt-SysRq-R
  12. Virtual memory is prohibitively expensive on a system that lacks a TLB because
    • Every memory access then requires a system call.
    • The page table has to be checked on every memory access
    • The process table has to be updated on every tick interval.
    • None of the above