List of questions (ITI8510) - Redigeerimiste ajalugu

Irve: /* Lecture 12: Real-Time Operating Systems */

2011-05-20T10:17:34Z

Lecture 12: Real-Time Operating Systems

←Vanem redaktsioon		Redaktsioon: 20. mai 2011, kell 12:17
177. rida:		177. rida:
	* How does VxWorks ease development of RT-systems?		* How does VxWorks ease development of RT-systems?
	* How did uC/OS-II start and why is it popular?		* How did uC/OS-II start and why is it popular?

	~~Aside: Processor registers are something that need explaining before the task internals. (For next year)~~

Irve: /* Lecture 10: Networking */

2011-05-20T10:17:13Z

Lecture 10: Networking

←Vanem redaktsioon		Redaktsioon: 20. mai 2011, kell 12:17
160. rida:		160. rida:
	** creating and listening on a socket to create a server?		** creating and listening on a socket to create a server?
	** Why is it necessary to create a handler for EPIPE signal when working with sockets?		** Why is it necessary to create a handler for EPIPE signal when working with sockets?


	== Lecture 11: Getting to know the hardware ==		== Lecture 11: Getting to know the hardware ==

Irve – 20. mai 2011, kell 10:13

2011-05-20T10:13:40Z

@@ 49. rida: / 49. rida: @@
 * How can interrupt priorities be handled in software?
-== Lecture 4: Interrupts, signals, threads ==
+== Lecture 4: Understanding memory (Stack) ==
 * How is protected mode related to interrupts?
@@ 66. rida: / 96. rida: @@
 * How can a mutex solve race conditions?
-== Lecture 5: Scheduling ==
+== Lecture 7: Scheduling ==
 * Are the goals for scheduling - processor usage maximization and response time maximization mutually exclusive?
@@ 81. rida: / 111. rida: @@
 * How can paging affect real time processes and what can be done to avoid it?
-== Lecture 6: Programming an operating system ==
+== Lecture 8: Programming an Operating System ==
 * What would be the minimal data that is stored for a suspended task?
@@ 93. rida: / 123. rida: @@
 * Describe locking/setting of a mutex which uses a waiting list.
 * What is a deadlock?
 == Lecture 9: Optimization ==
@@ 145. rida: / 145. rida: @@
 * Describe problems which optimization can introduce.
-== Lecture 10: Getting to know the hardware ==
+== Lecture 10: Networking ==
 * Describe the difference between Unix IO and Standard IO functions.
@@ 167. rida: / 160. rida: @@
 ** creating and listening on a socket to create a server?
 ** Why is it necessary to create a handler for EPIPE signal when working with sockets?
 == Lecture 12: Real-Time Operating Systems ==

Irve: /* Lecture 11: Networking */

2010-05-26T01:12:07Z

Lecture 11: Networking

←Vanem redaktsioon		Redaktsioon: 26. mai 2010, kell 03:12
164. rida:		164. rida:
	* What does a socket address store?		* What does a socket address store?
	* What is the sequence of functions for:		* What is the sequence of functions for:
	* creating and connecting a socket to a computer?		** creating and connecting a socket to a computer?
	* creating and listening on a socket to create a server?		** creating and listening on a socket to create a server?
	* Why is it necessary to create a handler for EPIPE signal when working with sockets?		** Why is it necessary to create a handler for EPIPE signal when working with sockets?

	== Lecture 12: Real-Time Operating Systems ==		== Lecture 12: Real-Time Operating Systems ==

Irve: /* Lecture 12: Real-Time Operating Systems */

2010-05-24T00:47:03Z

Lecture 12: Real-Time Operating Systems

←Vanem redaktsioon		Redaktsioon: 24. mai 2010, kell 02:47
178. rida:		178. rida:
	* How did uC/OS-II start and why is it popular?		* How did uC/OS-II start and why is it popular?

	Aside: Processor registers are something that need explaining before the task internals.		Aside: Processor registers are something that need explaining before the task internals. (For next year)

Irve: /* Lecture 4: Interrupts, signals, threads */

2010-05-11T16:31:50Z

Lecture 4: Interrupts, signals, threads

←Vanem redaktsioon		Redaktsioon: 11. mai 2010, kell 18:31
60. rida:		60. rida:
	* What are the possible registered default actions for a signal?		* What are the possible registered default actions for a signal?
	* Is it possible for several signals of the same type to arrive while blocked or pending?		* Is it possible for several signals of the same type to arrive while blocked or pending?
	* What are the common patterns for writing ~~signals~~?		* What are the common patterns for writing signal handlers?
	* Threads: should only know what is a thread, since they were used as a tool for explaining data sharing and critical sections for concurrent programming.		* Threads: should only know what is a thread, since they were used as a tool for explaining data sharing and critical sections for concurrent programming.
	* What is a race condition?		* What is a race condition?

Irve: /* Lecture 12: Real-Time Operating Systems */

2010-05-11T15:24:27Z

Lecture 12: Real-Time Operating Systems

←Vanem redaktsioon		Redaktsioon: 11. mai 2010, kell 17:24
177. rida:		177. rida:
	* How does VxWorks ease development of RT-systems?		* How does VxWorks ease development of RT-systems?
	* How did uC/OS-II start and why is it popular?		* How did uC/OS-II start and why is it popular?
	*

	Aside: Processor registers are something that need explaining before the task internals.		Aside: Processor registers are something that need explaining before the task internals.

Irve – 11. mai 2010, kell 15:23

2010-05-11T15:23:16Z

Uus lehekülg

{{iti8510}}

This list of questions serves as a pool of questions that might be present at the exam. Your mileage may vary. The image is illustrative. Items in mirror may be closer than they appear.

== Lecture 1: Introduction ==

* What are real-time systems?
* What are the main characteristics of real-time systems?
* How did priority inversion affect Pathfinder rover in 1997?
* What is priority inheritance?
* Describe the difference between synchronous and asynchronous events
* How does state based system differ from event based system?
* What is deterministic real-time system?
* What is the difference between soft, firm and hard real-time systems?
* When workload changes but resources remain constants: is it possible to create statically predictable real-time system?
* What are the possibilities for certifying a dynamic real-time system?
* What is latency?
* What system constraints can create design conflicts apart from real-time requirement?

== Lecture 2: Real-Time Operating Systems ==

* Why are operating systems created?
* Describe the possible services for operating systems.
* What services are usually not included in real-time operating systems?
* Why is predictablility, for RTOS, more important than speed?
* What is re-entrancy and why is it important for RTOS libraries?
* Why is buying a RTOS considered better than writing one?
* What is POSIX?
* What are the problems for Linux as RTOS? Benefits?
* How does RTLinux run RT tasks?
* Describe possible scheduling strategies. Which are feasible for RTOS?

== Lecture 3: Input / Output ==

* What is memory mapped hardware access?
* For memory mapping: how do you write into a device's registers?
* What is IO mapped hardware access?
* What does port polling mean?
* Explain the difference between blocking and nonblocking IO operations
* Why is IO blocking needed at all?
* How is select() function used?
* How do interrupts help IO?
* What are the architectural requirements for CPU to support interrupts?
* What happens when interrupt line activates on CPU?
* Why can interrupts be generated internally in CPU?
* Interrupt types: Polling, Interrupt Vector Table (IVT), Programmable Interrupt Controller (PIC)
* How vector interrupts work? What is Interrupt Vector Table (IVT)
* Explain the first and last actions of an Interrupt Service Routine.
* How can interrupt priorities be handled in software?

== Lecture 4: Interrupts, signals, threads ==

* How is protected mode related to interrupts?
* Why are interrupts considered synchronous and asynchronous?
* Why are interrupts sometimes blocked?
* Explain access serialization as a method for data protection
* What are system calls and how are they related to interrupts?
* Explain how signals are different from and similar to (hardware) interrupts?
* Do blocked signals wait or are they discarded?
* What are the possible registered default actions for a signal?
* Is it possible for several signals of the same type to arrive while blocked or pending?
* What are the common patterns for writing signals?
* Threads: should only know what is a thread, since they were used as a tool for explaining data sharing and critical sections for concurrent programming.
* What is a race condition?
* What is a mutex?
* How can a mutex solve race conditions?

== Lecture 5: Scheduling ==

* Are the goals for scheduling - processor usage maximization and response time maximization mutually exclusive?
* What does it mean for scheduling to be preemptive; non-preemptive?
* What is static scheduling?
* What are the problems of round-robin scheduling?
* How does rate monotonic scheduling work?
* Can you find cases in which Earliest Deadline First is better than Rate Monotonic Scheduling?
* How does a simple cyclic executive work?
* What are the three intuitive priority levels for cyclic executive?
* What can be done if you have a task which takes 100ms and time-slot is only 60ms and the task exeeds its time slot?
* What happens if a POSIX process is set to be scheduled with SCHED_RR; SCHED_FIFO?
* Can you set priorities for tasks which are scheduled with SCHED_OTHER
* How can paging affect real time processes and what can be done to avoid it?

== Lecture 6: Programming an operating system ==

* What would be the minimal data that is stored for a suspended task?
* What are the three common states for tasks?
* What is a scheduling point?
* What is the purpose of OS clock tick?
* What is stored in a ready list?
* Why is there an idle task?
* How does context switch work?
* Why one cannot write context switching without assembly code?
* Describe locking/setting of a mutex which uses a waiting list.
* What is a deadlock?

== Lecture 7: Understanding memory (Stack) ==

* What kind of memory is faster to access than RAM?
* What are the possible operations of a stack data structure?
* Write a short possible stack implementation in C
* What are the hardware requirements for stack implementation?
* What characteristics of assembly language make it unpopular?
* What is the purpose of registers %esp and %ebp on IA32 architecture?
* Can you refer to memory addresses in assembly?
* What do the assembly commands "push %eax"; "pop %edx" do?
* Explain the contents of a non-active stack frame
* How are call, leave and ret operators used?
* In general: while it's good to know the stack on operator level, general understanding of its workings should be sufficient. See slides "Recap" and "Stack frame"
* Why are some registers Caller save and some Callee save registers?
* Explain some of the ways in which call stack affects the behaviour of C programs.
* Explain how overflowing buffers are exploited by hackers.

== Lecture 8: Understanding memory (Heap) ==

* What does "brk" pointer hold?
* Why is dynamic allocation avoided for Real-Time Systems?
* How can fragmentation reduce the amount of free memory?
* In theory you could solve fragmentation by moving memory contents. Why it is not done?
* How are block headers hidden from modification?
* Why can we use 3 lower bits of block size in header to store data?
* Describe first fit; next fit; best fit allocation strategies
* Sometimes it is necessary to join memory blocks, when is it done?
* Why are free memory blocks sometimes segregated?
* What is Garbage Collection?

== Lecture 9: Optimization ==

* Why is optimization not the default option for compilers?
* Describe some of the limitations for optimization.
* Why is cycles per element better way of measuring optimization than running time?
* Explain the reasoning behind following optimizations:
** Move calculations out of loop
** Reduce function calls
** Extra storage variables in loops
** Loop unrolling
** Pointer access for arrays
* How can knowledge of CPU pipelining help optimization?
* How can cache and branch prediction affect optimization.
* What is code profiling?
* Why is C99 standard suggesting use of ''inline'' keyword in stead of a macro?
* What methods can you use to reduce:
** code size?
** memory usage?
** power consumption?
* Describe problems which optimization can introduce.

== Lecture 10: Getting to know the hardware ==

* What general steps are needed for undestanding the hardware?
* Why are hardware component datasheets interesting for a programmer?
* Describe some of the things an assembly programmer should know about the processor.
* Why is it necessary to use assembly in initialization code?

== Lecture 11: Networking ==

* Describe the difference between Unix IO and Standard IO functions.
* What are the main functions for Unix IO?
* There are 3 structures for storing open files in a system kernel: what are they?
* How many bytes are there in an IP-address?
* What is the purpose of DNS services?
* Is network byte order little- or big-endian? What does it mean?
* What function is used for domain name retrieval?
* What is a socket?
* What does a socket address store?
* What is the sequence of functions for:
* creating and connecting a socket to a computer?
* creating and listening on a socket to create a server?
* Why is it necessary to create a handler for EPIPE signal when working with sockets?

== Lecture 12: Real-Time Operating Systems ==

* Which of the following are very popular RTOS-es? (w/ some list)
* What is the background for OSEK/VDX standard?
* What is a priority ceiling?
* Nucleus has a very uncharacteristic feature for an RTOS, what is it?
* VxWorks is a pun on another operating system, which?
* How does VxWorks ease development of RT-systems?
* How did uC/OS-II start and why is it popular?
*

Aside: Processor registers are something that need explaining before the task internals.