Term
| What is an operating system? |
|
Definition
| program that acts as an intermediary between user of a computer and hardware |
|
|
Term
| What do users want in an operating system? what do they not care about |
|
Definition
ease of use
resource utilization |
|
|
Term
|
Definition
| one program running at all times on the computer |
|
|
Term
| what way is the computer a resource allocator? |
|
Definition
| manages resources of computer and resolves conflicts of use |
|
|
Term
| how is an operating system a control program? |
|
Definition
| prevents errors and improper use of the computer |
|
|
Term
| what is a bootstrap program? |
|
Definition
| firmware loaded upon startup or reboot that loads the operating system kernal and begins execution |
|
|
Term
|
Definition
| code in the computer that is permanent |
|
|
Term
| what do device controllers do? |
|
Definition
| act as intermediaries between hardware and memory |
|
|
Term
|
Definition
| informs the cpu that a device controller (hardware or software) has finished its operation |
|
|
Term
| what is an interrupt vector? and what must it do? |
|
Definition
contains the addresses of all service routines.
must save the address of the interrupted instruction |
|
|
Term
| how are interrupts handled? |
|
Definition
1.address of interrupted instruciton is saved
2. incoming interupts are disabled
3. type of interrupt received is determined
4. interrupt is handled |
|
|
Term
|
Definition
| a software-generated interrupt caused by an error or user request |
|
|
Term
| what is interrupt driven? |
|
Definition
|
|
Term
|
Definition
|
|
Term
| what does random access memory allow for? |
|
Definition
| we can go straight to that location in memory |
|
|
Term
|
Definition
| is not erased when computer loses power orf reboots, does not run on power |
|
|
Term
| how is a hard disk divided? |
|
Definition
| tracks, and then into sectors |
|
|
Term
| what is a disk controller? |
|
Definition
| determines the logical interaction between device and computer |
|
|
Term
|
Definition
| copying informaiton into faster storage system |
|
|
Term
| what is the fastest memory, 2nd |
|
Definition
|
|
Term
| what are multiprocessors systems also known as? (2 things) |
|
Definition
| parallel systems, tightly-coupled systems |
|
|
Term
| 3 advantages of multiprocessor systems? |
|
Definition
1. increased throughput (more horsepower)
2. economy of scale
3. increased reliability (graceful degredation or fault tolerance |
|
|
Term
| what is the difference between asymmetric multiprocessing and symmetric multi processing? |
|
Definition
| asymmetric processing has one dominant processor and symmetric processing has processors the work together as peers |
|
|
Term
|
Definition
| there is a backup if one fails |
|
|
Term
| what is multiprogramming? |
|
Definition
| organizes jobs so CPU always has a job to execute and things are done as efficiently as possible |
|
|
Term
|
Definition
| switching between jobs to allow the user to interact with each job even when a process is running |
|
|
Term
|
Definition
| a program executing in memory |
|
|
Term
| what is the difference between user and kernal mode? |
|
Definition
| kernal mode has privleged instructions that interact with the hardware, user mode does not directly interact with the hardware |
|
|
Term
| what type of entity is a program, process? |
|
Definition
|
|
Term
|
Definition
| any mechanism for controlling access to processes or users to resources defined by OS |
|
|
Term
|
Definition
| defense against external attacks |
|
|
Term
| user id and group id do what? |
|
Definition
| identify users and groups to associate privledges to a user |
|
|
Term
| what are 2 types of user interfaces? |
|
Definition
| command-line interface (CLI) and graphical user interface (GUI) |
|
|
Term
| what are two ways a CLI can be implemented? |
|
Definition
inside the kernal where the kernal understands the instructions
other method is systems programs which the CLI only understands the file to be executed |
|
|
Term
| how are most systems programs accessed by developers? |
|
Definition
| application programming interfaces (APIs) |
|
|
Term
| what are APIs more useful than systems calls? |
|
Definition
| less complicated, and can work on a variety of systmes |
|
|
Term
| What does the api allow in terms of what the user needs to know when making systems calls? |
|
Definition
| user just needs to know what will happen with a given system call |
|
|
Term
| what are the 3 ways to pass parameters ot the OS? |
|
Definition
1. registers
2. blocks
3. stacks |
|
|
Term
| what are system goals for designing operating systems? (4 goals) |
|
Definition
1. easy to design, implement, and maintain
2. reliable
3. error-free
4. efficient |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| why do you need to seperate policies from mechanisms? |
|
Definition
| you must determine policies before developing mechanisms to acheive those policies |
|
|
Term
| what must policies be, and what must mechanisms be? |
|
Definition
policies must be specific
mechanisms must be flexible |
|
|
Term
| one example of policy that has changed over years in windows systems |
|
Definition
| functionality for multiple users has been added |
|
|
Term
| What are the 4 approaches to OS design? |
|
Definition
1. simple
2. layered
3. micokernal
4. modular |
|
|
Term
| what is the simple design of an operating system? |
|
Definition
| a big program with little seperation between componenets |
|
|
Term
| what is the layered design for operating systems? how are layers accessed? |
|
Definition
operating system is divided into levels
bottom layer is hardware
top is the user interface
each layer accesses layers below it |
|
|
Term
what are advantages to layered approach?
disadvantages? |
|
Definition
adv: more structured design to prevent bugs
disadv: slower running, very big
needs to talk between layers |
|
|
Term
| what is a microkernal system? |
|
Definition
most of kernal is in user space
message passing between modules |
|
|
Term
adv of micro kernal
dis of micro kernal |
|
Definition
adv: really small kernal allows faster runtime of kernal
dis: system is slowed doswn |
|
|
Term
| what do modular systems do? |
|
Definition
allow access between all modules without the need for message passing
components reside in kernal space |
|
|
Term
| name an example of a module in the modular approach |
|
Definition
| device drivers are located in the kernal |
|
|
Term
| virtual machines do what? |
|
Definition
| provide an interface identical to underlying hardware |
|
|
Term
| what do viritual system hosts do for the user? |
|
Definition
| create the illusion that a process has its own processor |
|
|
Term
| what do guests on a virtual system have? |
|
Definition
| virtual copy of the underlying computer |
|
|
Term
|
Definition
| consolidations of resources into onto one hardware |
|
|
Term
| what is the main problem with vmware? |
|
Definition
| slow, there is another layer the computer needs to deal with |
|
|
Term
|
Definition
| finding and fixing errors or bugs |
|
|
Term
|
Definition
| generated by the os containing error info |
|
|
Term
|
Definition
| when an applicaiton fails a core dump is generated capturting memory of the process |
|
|
Term
|
Definition
| kernal memory is captured when operating system failure occurs |
|
|
Term
|
Definition
| locates kernal, loads it into memory, and starts it |
|
|
Term
|
Definition
| second-step in two step startup bootloader loats boot block |
|
|
Term
|
Definition
|
|
Term
| what are the states of a process (5)? |
|
Definition
new,
running,
waiting (for event)
ready (to be assigned)
terminated |
|
|
Term
|
Definition
| when cpu switches process, must save state of one and load new |
|
|
Term
| what is important about context switch time |
|
Definition
|
|
Term
|
Definition
| amount of time alloted for a process to finish |
|
|
Term
|
Definition
| maintinas scheduling log to keep track of various queues |
|
|
Term
|
Definition
| does more i/o than calucaitons, short cpu bursts |
|
|
Term
|
Definition
| more calculations than i/o, long cpu bursts |
|
|
Term
| what is a parent process? |
|
Definition
| creator of children processes |
|
|
Term
| what does every process have? |
|
Definition
|
|
Term
|
Definition
| no limit to size of buffer |
|
|
Term
|
Definition
| limited size, producer cannot over fill quie, and user cannot empty and more |
|
|
Term
| direct message communicaiton |
|
Definition
| sender and receiver process |
|
|
Term
|
Definition
| uses a mailbox in memory shared by both processes |
|
|
Term
|
Definition
| is synchronous sender sends til message recieved, receiver waits til available |
|
|
Term
|
Definition
| sender sends and moves on, receiver receives message or null |
|
|
Term
| How does an operating system get loaded into memory when a computer is powered on? |
|
Definition
| bootstrap program is loaded at powerup/reboot and intializes all aspects of system and begins execution of kernal |
|
|
Term
| Explain the purpose of an interrupt vector. |
|
Definition
| Interrupt vector contains all addresses of service routiners to deal with interrupt requests and how to handle them |
|
|
Term
| There are two different ways that commands can be processed by a command interpreter. One way is to allow the command interpreter to contain the code needed to execute the command. The other way is to implement the commands through system programs. Compare and contrast the two approaches. |
|
Definition
Key answer: can dynamically load programs and extend command interface
If the command was a monolithic program, then it would be hard to update, which you would mean that you would have to access the operating system.
Command interpretor dynamically loads commands. Commands are stored as single commands in the operating system. If it loads commands, we can create new commands and we can extend the system. |
|
|
Term
|
Definition
| allows for multiple tasks to be run within a single process |
|
|
Term
| how would threading help a web browser? |
|
Definition
| you could send keyboard input without pausing the download of an image, and update the GUI |
|
|
Term
| what advantages does thread creation have against process creation? |
|
Definition
| process creations is heavier and thread creation can share resources |
|
|
Term
| What are 4 benefits of threading? |
|
Definition
1. responsiveness
2. resource sharing
3. economy
4. scalability |
|
|
Term
| what is the responsiveness benefit of multithreading? |
|
Definition
| you can do multipel things at once: i.e. download an image while moving hte mouse and reading from I/O devices |
|
|
Term
| what is the advatnage of resource sharing from multithreading? |
|
Definition
| memory is shared between threads and you do not need to have message passing |
|
|
Term
| what is the economy benefit of multithreading? |
|
Definition
| you do not need to copy data. since memory is shared, each thread has access to the same data |
|
|
Term
| what is the scalabily benefit of multithreading? |
|
Definition
| if you add more processors, work can be completed faster, allows for work to be done on multiple tasks rather than one process at a time |
|
|
Term
| what are 3 models for multithreading? |
|
Definition
1. many to one
2. one to one
3. many to many |
|
|
Term
| what is the many to one model of multithreading? one disadvantage? |
|
Definition
multiple user threads correspond to one kernal thread.
dis: if your process blocks, then all threads will be stopped |
|
|
Term
what is the one to one model of threading?
what is one disadvantage? |
|
Definition
one user thread to each kernal thread
dis: there is a greate deal of overhead created from the context switches between processes |
|
|
Term
| what is the many to many model of multithreading? |
|
Definition
| there are equal or less number of kernal threads for every user thread, kernal threads are created when needed |
|
|
Term
| what are the two types of thread cancellation? |
|
Definition
| asynchronus and defferred |
|
|
Term
| what is asynchronus thread cancelation? why is it dangerous? |
|
Definition
one thread is immediately terminated
it is dangerous because if resources are associated with a thread, then they are no longer available |
|
|
Term
| what is deffered thread cancelation? |
|
Definition
| the target thread periodically checks to see if it should terminate |
|
|
Term
|
Definition
| notificaitons that an event has occured on a UNIX system |
|
|
Term
| what are the waysto handling a signal by a multithreaded process? (4 ways) |
|
Definition
1. deliver signal to thread which applies
2. deliver signal to every thread in process
3. devliver signal to specific threads in process
4. assign a specific thread to receive all signals for the process |
|
|
Term
| What can classify as an operating system? |
|
Definition
| the one program running at all times, or everything the vendor ships with the os |
|
|
Term
| What is a systems program? |
|
Definition
| a program that is associated with the operating system and can have access to hardware, but not part of kernal |
|
|
Term
| What are the two types of programs outside of the operating system? |
|
Definition
| system programs and applicaitons programs |
|
|
Term
| what is an applications program? |
|
Definition
| all programs not associated with the operating system |
|
|
Term
| what are examples of device controllers? name 3 |
|
Definition
| disk drive, audio devices, video displays |
|
|
Term
| what is a device controller? |
|
Definition
| in charge of handling devices with the CPU |
|
|
Term
| what is secondary storage? |
|
Definition
| extenion of main memory (volatile) |
|
|
Term
| what is most common form of secondary storage? |
|
Definition
|
|
Term
| what is the storage-device heiarchy (top to bottom)? 7 levels |
|
Definition
1. registers
2. cache
3. main memory
4. electronic disk
5. magnetic disk
6. optical disk
7. magentic tapes |
|
|
Term
|
Definition
| can suffer a failure of any given component and still operate |
|
|
Term
| what is graceful degredation? |
|
Definition
| to continue servicing proportional to surviving hardware |
|
|
Term
| what does multiprogramming aim to do? |
|
Definition
| organize jobs efficiently so CPU always has one to execute |
|
|
Term
| what happens if there is nothing to do? |
|
Definition
| if there is nothing to do, operating system will wait until a user request from a user program or error occurs |
|
|
Term
| what does being interrrupt driven mean? |
|
Definition
| that the compute will wait until events occur, and will then respond to those events |
|
|
Term
| what are the two modes presented by an operating system? |
|
Definition
| user mode and system mode |
|
|
Term
|
Definition
| no access to operating system or hardware |
|
|
Term
|
Definition
| privleged instructions made accessing hardware |
|
|
Term
| how does dual-mode relate to protection? |
|
Definition
| it prevents privleged instructions from being made and harming the computer by reserving the os to make them |
|
|
Term
| what does the program counter do? |
|
Definition
| specifies the next instruciton to execute |
|
|
Term
| What is the difference between protection and security? |
|
Definition
protection is any mechanism for controlling hte access of processes or users to the resources defined by a computer system
security prevents external and internarl attacks |
|
|
Term
| what does linux use to protect files? |
|
Definition
| Linux uses privledges to protect files, and assigns privleges to appropriate users |
|
|
Term
| how does the CLI interface work with linux? does the command line prompt understand? |
|
Definition
1. the user chooses a shell to use
2. enters a command to be exucted by the system
the command line prompt does not understand the program, but identifies the specified file which executes the program through use of systems programs |
|
|
Term
| what is s aystem call? and example of use with selecting files? |
|
Definition
provides an interface to servies made available by the operating system
user need opens file using a graphical user interface, opening the file occurs through I/O system calls, then opening input and creating output also require calls |
|
|
Term
| How does an API relate to systems calls? what does this do for the user? |
|
Definition
an api provides functions that usually implement systems calls. less complex environment to operate
cross platform functionality |
|
|
Term
| What are the 5 types of systmes calls and a little info on each |
|
Definition
1. process control-ending creating processes
2. file management-opening, closing, deleting, readingfiles
3. device management-attach/detach devices, read from
4. information maintainance-get time or date, get process attributes status
5. communicaitons-create connctions, send/receive messages |
|
|
Term
| goals of os design? 5 of them |
|
Definition
1. convenient
2. easy to learn
3. reliable
4. safe
5. fast |
|
|
Term
| simple stucture adv. and disadv |
|
Definition
no real benefits
dis: not well-defined, system crashes and vulnerabilties |
|
|
Term
| layerd approach adv and dis: |
|
Definition
adv: better debugging and simplicity, individual layers debugged one at a time
dis: less efficient than |
|
|
Term
|
Definition
adv: easily extendable because it primarily uses systems programs, just tack on another program
dis: decreased performance due to system overhead |
|
|
Term
|
Definition
adv: small kernal which acts a communicator between moduales, easily extendable
dis: none really |
|
|
Term
| what are benefits of virtual machines 3 of them |
|
Definition
1.host is protected, client program operate in isolaiton, so no way to go after host or other clients
2. allows swithcing between operating systems
3. runs multiple machines on one set of hardware |
|
|
Term
| what are approcahes to virtual machines? |
|
Definition
1. simulation-use of an emulator to run outdated systems products
2. paravirtulizaiton- working on similar systems |
|
|
Term
| what is big problem with virtual machines? |
|
Definition
| it takes time because you are operating with another layer |
|
|
Term
| parts of process and descr. 5 parts |
|
Definition
1. text section- the program code
2. program counter-current activity
3. stack-contains temporary data
4. data section-contains global variables
5. heap-memory is dynamically allocated during process runtime |
|
|
Term
| what are 5 process states and descrp. |
|
Definition
1. new-being created
2. running-instructions being executed
3. waiting-waiting for event
4. ready-ready to be assigned to processor
5. terminated-finished execution |
|
|
Term
| what is a process control block and what info does it hold? 7 parts |
|
Definition
contains information about processes
1. process state-running? waiting?
2. program counter- address of next instruciton to execute
3. CPU registers-variety of data inluding info during switches
4. CPU-scheduling info-process priority and scheucling info
5. memory management info-info regarding limits on memory
6. accounting-statistics re: process
7. I/O status informaiton-list of devices to a process |
|
|
Term
|
Definition
| deals with tasks that will run a long time, and is careful when scheduling to maximize efficiency |
|
|
Term
|
Definition
| quickly running, switches between programs frequently, shorts programs usually |
|
|
Term
|
Definition
| swapping is introduced, swapping out processes in execution for better ones |
|
|
Term
| what is cascading termination? |
|
Definition
| if parent does not exist, then child is terminated as well |
|
|
Term
| what is symmetry in addressing? |
|
Definition
| both receiver and sender are required to provide info on other process to communicate |
|
|
Term
| what is asymmetry in addressing? |
|
Definition
| only sender needs to know receiver, receiver doesnt care |
|
|
Term
| 4 types of synchronization and des |
|
Definition
1. blocking send-sending process blocked until message received by process or mailbox
2. nonblocking send-sending process sends and resumes
3. blocking receive-reciver blocks until message is available
4. nonblocking recieve-reciever retrieve valid or null message |
|
|
Term
| sockets in message passing? |
|
Definition
| provide uniquie id, IP address |
|
|
Term
| what is a threads library? |
|
Definition
| provides api for programmer to use in creating and managing threads |
|
|
Term
| what are 3 appraoches to thread libraries? |
|
Definition
1. provide library in user space w/o kernal support
2. kernal-level library provided by operating system |
|
|
Term
| when does a process go from running to waiting? |
|
Definition
| when it needs input from i/o |
|
|
Term
| what would happen if time slice were problomatically short? |
|
Definition
| too much overehead would be created from the context switches |
|
|
Term
|
Definition
pointer to a character type
used in definition of arrays |
|
|
Term
| what is *x where x is an int |
|
Definition
| pointer to value held in x |
|
|
Term
| what is x when x is relating to pointers |
|
Definition
| the pointer pointing to an int |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
|
Definition
| pointer to a pointer of an int |
|
|
Term
|
Definition
| (type "%d", address of variable to store in "&lim) |
|
|
Term
|
Definition
| (type "%d", variable to be printed) |
|
|
Term
| how to change permissions using command line? |
|
Definition
|
|
Term
|
Definition
| allows the user to interact with the kernal |
|
|
Term
| how do you access the bourne shell? and what is it in comparison to the bourne again shell? |
|
Definition
|
|
Term
| how do you access the bourne again shell? |
|
Definition
|
|
Term
| how do you see the programs you have running? |
|
Definition
|
|
Term
| what does the "which" command do? |
|
Definition
| finds location of executable |
|
|
Term
what two parameters are part of main function reading command line arguements?
what do they represent? |
|
Definition
int argc and char**argv
number of commnads
the commands themselves (a space designates new command) |
|
|
Term
| what must you do with files at end of prgram? |
|
Definition
|
|
Term
|
Definition
| fopen(name of file, how to open ("r" would mean reading only)) |
|
|
Term
| how do you read and write individual characters?q |
|
Definition
|
|
Term
| how do you read chuncks of characters? |
|
Definition
|
|
Term
| what are adv of fread and fwrite? |
|
Definition
|
|
Term
| what must happen in a fork before a parent process executes? |
|
Definition
| the child must finish executing first |
|
|
Term
| what pid represents child in a fork()? |
|
Definition
|
|
Term
| what type of communicaiton is communicaiton between two sockets? |
|
Definition
|
|
Term
| what type of communication is pipes? and what do they do? |
|
Definition
one way
filter out data presented from command |
|
|
Term
| what does *-- in pthreads library mean? |
|
Definition
| pointer to location of function in meemory |
|
|
Term
|
Definition
|
|
Term
what does the exec() command do?
after a fork() call? |
|
Definition
exec command replaces an entire process and all threads
after a fork call it replaces the newly created process with the process listed in the parameter |
|
|
Term
|
Definition
| interpretor of command line commands |
|
|
Term
| use fgetc and fputc in code |
|
Definition
|
|
Term
| how to do file reading and writing with fread() and fwrite() |
|
Definition
same as other, but currsize=current size of buffer, which fread returns
size=size of buffer |
|
|
Term
|
Definition
| scanf(type,address of variable to store) |
|
|
Term
what is stdin?
what is one way we have used it when reading files with buffers? |
|
Definition
standard input, commands input from the keyboard in cli
hit new line to show next 5 lines of code |
|
|
Term
| in terms of diagrams, what does the child process and the parent process do? |
|
Definition
child: executes and exits
parent: waits until child exits then runns |
|
|
Term
what is a pipe?
where do we see them? |
|
Definition
standard method of communication between processes
between the command line output and input of another program to be printed |
|
|
Term
| what thread library uses pthreads()? |
|
Definition
|
|
Term
| what are differences between fork() and exec()? |
|
Definition
fork creates a new process
exec replaces process and containing threads |
|
|
Term
| what is one way to look at fork() example with letter |
|
Definition
| if it is "!pid", then it is the parent |
|
|
Term
| what is a cooperating process? |
|
Definition
| process that can affect or be affected by other processes |
|
|
Term
|
Definition
| sees what system calls are made |
|
|
Term
| what could be a problem with useing the same system call interface for files and devices? |
|
Definition
| they are similar, and the user may not realize differences in how they are handled |
|
|
Term
| how are commands interpreted in linux? |
|
Definition
| through a shell in user space |
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Term
| what are the two primary forms of interprocess communication? |
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Definition
| message passing and shared memory |
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