IO Systems
Last modified Tuesday, 30-Nov-2004 12:23:49 UTC.
- IO systems
(Slides)
- IO Hardware
- Device features (SGG Ch.13.2)
- Device abstraction (SGG Ch.13.2.0, Ch.13.3.0-1)
- Kernel IO subsystem
- IO interface (SGG Ch.13.3)
- Scheduling (SGG Ch.13.4.1)
- Buffering (SGG Ch.13.4.2)
- Caching (SGG Ch.13.4.3)
- Error handling (SGG Ch.13.4.5)
- IO Requests
- Forms of IO
- Interrupts (SGG Ch.13.2.2)
- Polling (SGG Ch.13.2.1)
- Special Services
- DMA (SGG Ch.13.2.3)
- Spooling and device reservation (SGG Ch.13.4.4)
- Network interface
- Data structures (SGG Ch.13.4.6)
- UNIX IO system
- IO structure
- Block buffer cache
- C-lists
- Raw device access
- Disk management
(Slides)
- Disk scheduling (SGG Ch.13.2)
- FCFS scheduling (SGG Ch.13.2.1)
- SSTF scheduling (SGG Ch.13.2.2)
- SCAN scheduling (SGG Ch.13.2.3)
- C-SCAN scheduling (SGG Ch.13.2.4)
- C-LOOK scheduling (SGG Ch.13.2.5)
- Bad block management (SGG Ch.13.3.3)
- Manual handling via block allocation (delete from free list)
- Sector sparing
- Sector slipping
- Swap space management (SGG Ch.13.4)
- Disk reliability (SGG Ch.13.5)
Exam Style Questions
- What do device drivers do in an OS?
- Briefly describe two ways in which an application may cause a device
driver to perform IO tasks.
- When an application requests IO activity, how is the request sometimes
satisfied without the IO device being used?
- Differentiate between interupt drive IO and polling? In what sort of
situations is polling more appropriate than interupt driven IO?
- List the six basic steps in DMA.
- How does DMA improve the performance of a computer system?
- What is the difference between a block device and a character device?
Give an example of each.
- What is "buffering"? Give three reasons for an OS to use buffering.
- Differentiate between buffering and caching.
- In what circumstances would an operating system use SPOOLing or
device reservation? What is the potential danger of device reservation?
- Explain the differences in an operating system's response between
transient and permanent IO failures.
- What is a "block" in an OS file system?
- Define disk bandwidth.
- How can disk scheduling improve OS performance?
- Given the following sequence of disk request track numbers, list
the order in which they will be services by the {FCFS,SSTF,SCAN,C-SCAN,
LOOK,C-LOOK} disk scheduling algorithm. For each, give the total seek
time taken.
[List of track numbers, make up your own].
- What problems does the SSTF disk scheduling algorithm have?
- What is the weakness of the SCAN disk scheduling algorithm?
- How does the C-LOOK disk scheduling algorithm improve over the C-SCAN
algorithm?
- Explain two ways in which RAID technology is used to provide higher disk
reliability.