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Operating Systems II, Spring 2006, HW 1
This will be covered in practise session during the week 12 (20.-24.3.2006)These are normal, conventional homeworks. Problems are to be solved independently (or preferable working with a small group, with individual solutions) in advance at home and then the solutions are discussed in practice session. There will be no model solutions - make enough questions in the practice session.
- Interrupts, I/O
- What happens if a device interrupt (I/O interrupt) occurs but device interrupts are disabled? How can this problem be avoided? Why would one want to disable device interrupts?
- What trouble would it cause, if the processor would not be able to recognize I/O interrupts? Could one build a processor like this and for what purpose?
- Problem 1.8 [Stal05] (Probl. 1.8 [Stal01]) ("Problem", not "Review Question"!)
- Concurrency control
- What is the most important difference between synchronization with lock variables and synchronization with semaphores?
- Give an example situation where it would be advisable to synchronize with lock variables and not with semaphores.
- Give an example situation where it would be advisable to synchronize with semaphores and not with lock variables.
- Give an example situation where one definitely should not use (i) lock variables and (ii) semafores for synchronization.
- Considering synchronization with lock variables, what effect would
many processors with local caches have? Is this an advantage or disadvantage?
Would it be better to place lock variables to a non-cacheable memory
area (memory area that is not cached)? Why?
- Cache and TLB
- Problem 1.13 [Stal05] (Probl. 2.3 [Stal01])
- How does the situation change, if we consider also virtual memory
address translation and TLB?
Assume that address translation is done according to the Figure 8.8 [Stal05] (Fig. 8.8 [Stal01]) before cache access. TLB hit ratio is 99% and the page table is found in main memory with 95% probability. TLB has the same speed as cache.
- Scheduling
- Problem 2.3 [Stal05] (Probl. 2.4 [Stal01]) from the text book (higher level answers, no details)
- How do scheduling policies for optimizing real time systems differ
from those for time sharing and multiprogramming systems.
- W2K
- What advantages/disavantages is there with the HAL layer (Fig. 2.13 [Stal05] or Fig. 2.13 [Stal01])?
- Can Win32, DOS and POSIX applications simultaneously execute in W2K systems? If not, why? If yes, can the co-operate and how? Give an example where this feature could be (i) advantageous (ii) disadvantegous.
- MS-DOS has no threads but W2K has threads and a MS-DOS API (application program interface). Will this cause any problems? Give an example.
Teemu Kerola 06.03.2006 16:13