Operating Systems 3 Flashcards

Virtual memory
Terms Definitions
decryption
the decoding of data
loader
invoked by the control-card interpreter to load system programs and application programs into memory
802.11g
Wireless networking standard that operates in the 2.4GHz band w/a theoretical output of 54 Mbps and backward compatible with 802.11b
POST
Power-On-Self-Test. Refers to routines run immediately after power is applied. On power up, the main duties of POST are handled by the BIOS.
a)NTLDR
Which of the following files bootstraps Windows XP?a)NTLDRb)BOOT.INIc)BOOTSTRAP.EXEd)NTBOOTDD.SYS
DOS
the operating system originally used on IBM PCs
Cooperative multitasking
processes in multiprogramming which can affect or be affected by one another
sector
a space on a disk platter
True or false: Contiguous allocation is wasteful of space and does not allow files to grow.
True
CompTIA Network+ certification
vendor neutral, industry-wide certification for network technicians covering network hardware, installation and trouble shooting
Mailbox
can have multiple senders and receivers
Should an instruction to modify entries in a device status table be privileged?
Yes.
a)Hardware
Which type of resource do you configure in Device Manager?a)Hardwareb)Files and Foldersc)Applicationsd)Memory
Driver Signing
A technique developed by Microsoft, first introduced in Windows 2000 which tags drivers so the user would know it was tested and passed/approved by Microsoft to work correctly.
physical device
each of the actual peripherals attached to a computer
page table
maps virtual pages to physical frames
linker
the linker takes shared code in libraries and puts them together to run.
disk partition
separating the disk into different sections, so it appears to actually be multiple disks. Sometimes the OS doesn't have enough bits to access all the data in the disk
True or false: An in-memory mount table contains information about each mounted volume
True
True or false: the deadlock avoidance algorithm dynamicaly examines the resource-allocation state to ensure that there can never be a circular wait condition.
True
True or false: Logical addresses are generated by the CPU.
True.
True or False: Register access occurs in one CPU clock or less.
True
DEL(Erase)command
command in the command line interface used to delete/erase files
baud
one analog cycle on a telephone line
address space
memory addresses associated with a process
Should an instruction to turn off interrupts be privileged?
Yes.
real-time system
A system that responds instantly to input
Open Source
The operating system that can be examined and modified by users is known as _______ ________.
c)Active Partition
Which of the following partitions is specifically the partition from which the OS boots?a)Primary Partitionb)Extended Partitionc)Active Partitiond)Logical Partition
PAGEFILE.SYS
Located in the root directory of the drive which has the OS Files there is a file that is referred to as a swap file .. What is the name of the file and its extension?
Which operating system was the first release of a complete desktop operating system and the first to provide a graphical interface based around the start menu and taskbar?
windows 95
short-term scheduler
selects from among the processes that are ready to execute and allocates the CPU to one of them.
process control block
a process's represented in the operating system. It includes: the process state, program counter, CPU registers, CPU scheduling info, memory-management info, memory-management info, accounting into, I/O status info.
client/server system
Remote file systems allow a computer to mount one or more file systems from one or more remote machines. the machines containing the files is the server, and the machine seeking access to the files is the client.
thrashing
Memory is fully allocated. There is a chain of page faults, creates a queue of processes at the paging device. CPU goes close to 0.
device directory
a block(s) on disk containing data storing names, locations, lengths, owner, etc. of all files on disk. Data structures storing free block list. It is stored at a fixed location on disk. It has to search, create, delete, list, and backup files.
True or false: the MMU maps logical addresses dynamically.
What is EAT?
Effective access time describes the time requirement for demand paging. It is = (1-p)x time + p(avg. page fault service time).
active partition
On a hard drive, primary partition that contains an operating system
disk duplexing
type of disk mirroring using two separate controllers rather than one; faster than traditional mirroring
CAB files
cabinet files. These files are compressed and most commonly used during OS installation to store many smaller files, such as device drivers
RPC
called process is a part of a dedicated server
process manager functions
1.load, start, stop, resume processes correctly2.scheduling-sharing the CPU3.allocating other system resources to processes4.protecting one process from illegal incorrect interference by other processes5.helps communication and coordination among related processes6.prevent/remove deadlocks
Should a function to issue a trap instruction be privileged?
No.
Should an instruction to access an IO device be privileged?
Yes.
direct
Type of data access where you are able to locate a particular data item or file immediately, without having to move consecutively through items stored in front of the desired data item or file. Also called random access
Closed Source
when users can't modify or examine the code of a piece of software ..the software is categorized as _________ ______.
Which of the following operating system services is helpful for ensuring efficient operation of the system?
Resource allocation
Accounting
Protection and security
drivers
the term usually used in the PC world to refer to extensions to the operating system
physical address space
the set of all physical addresses corresponding to a logical address space.
general semaphore
a semaphore which can have any value between 0 and positive infinity
demand paging
load pages into memory only when a page fault occurs
placement strategy
determining where is the best place in memory to place a program
True or false: A pair of base and limit registers define the logical address space?
True
What happens when a child dies?
Parent may be notified
disk cloning
taking a PC and making duplicates of the hard drive,including all data, software and configuration files and transferring it to another PC
Should a function to set the value of the timer be privileged?
Yes.
Should the OS include web browsers and mail programs?
Fuck no.
Should a function to read the clock be privileged?
No.
d)Permissions grouped together for easy assignment
Standard Permissions are ______.a) The same as Special permissionsb)Only the Read, Write and Execute permissionsc)Permissions assigned to users but not to groupsd)Permissions grouped together for easy assignment
Legacy Devices
When Windows 95 came out many cards were not PnP compatible and were therefore referred to as _________ _________ .
Which of these is device management related?
request/release device
read, write, reposition
get/set device attributes
attach/detach devices
binary semaphore
a semaphore that can only have a value of either 0 or 1. Initial value of 1.
load control strategy
-determining how many jobs can be in memory at one time-determining how much of a job (how many pages of a job) can be in memory at one time
Address binding of instructions and data to memory address can happen at which different states.
During compiling, loading or execution.
What components comprise a process in RAM
Process stackData SectionHeapText section
boot sector
first sector on a PC hard drive or floppy drive, track 0. boot-up software in ROM tells the computer to load whatever program is found there.
What key do you press to display the last action performed in DOS?A F1B F2C F3D F4
C F3
How do we keep race conditions from happening?
With process synchronization.
Describe multilevel queue scheduling.
The ready queue is partitioned into several queues split up by priority or type or memory size.
What is preemptive scheduling?
Any scheduling that involves a process giving up the CPU before it's either terminated or gone from running to waiting on its own.
What is thread cancellation?
Thread cancellation is the task of terminating a thread before it has completed. Eg, if multiple threads are concurrently searching through a database and one thread returns the result, the rest can be canceled.
Suppose we are operating with execution-time binding and the physical address generated is 300. The relocation register is set to 100. What is the corresponding logical address?
200 (rel + log = phy)
What is internal fragmentation.
When memory is broken down into fixed sized blocks and allocates memory in units based on block size. With this approach, the memory allocated to a process may be slighly larger than the requested memory. The difference between the memory allocated and needed is the internal fragmentation -- unused memory that is internal to one particular partition.
What information is contained in a process control block (PCB)?
Process state Program counterCPU registersCPU schedulingMemory management informationAccounting informationI/O status information
You are configuring a wireless network using a wireless access point. Which of the following modes should you choose?A Native modeB Mixed modeC Ad Hoc modeD Infrastructure mode
D Infrastructure ModeThe IEEE 802.11 infrastructure mode is used to connect computers with wireless network adapters to an existing wired network
Name three major complications that concurrent processing adds to an os.
1)Processes have to share time 2)Processes must be protected from each other in memory and other resource use 3)Deadlocks have to be avoided
Describe shortest job first scheduling.
The shortest job in the readyqueue gets assigned to the CPU. This has very little waiting time, but starvation can occur for longer jobs.
What's the main difficulty a programmer must overcome in writing an OS for a realtime environment?
Scheduling must NOT permit response time to exceed the time constraint or things will crash.
What is waiting time?
The sum of all periods a process spends waiting for CPU time.
Pentium 233Mhz 64MB Ram1.5GB of Hard Drive Space
Minimum requirements for Windows XP Professional. (Processor, Ram, HD Space)
what different editions of windows 2000 were created?
it was available in several server editions as well as in a desktop version, windows 2000 Professional.
What defines the logical address space?
A pair of base and limit registers.
What is the fixed-length queue style of blocking message passing?
sender blocks if queue is full
What is the minimum amount of free disk space that should be available on a volume you wish to defragment?A 30% of free spaceB 15% of free spaceC 20% of free spaceD 10% of free space
B 15% of free space
Suppose a scheduling algorithm favors processes that have used the least time in the recent past. Why will this algorithm favor IO bound programs but not permanently starve CPU bound programs?
It will favor the I/O-bound programs because of the relatively short CPU burst request by them; however, the CPU-bound programswill not starve because the I/O-bound programswill relinquish the CPU relatively often to do their I/O.
What advantage is there to having diferent time quantum sizes at different levels of a multilevel queueing system?
Processes that need more frequent servicing, for instance, interactive processes such as editors, can be in a queue with a small time quantum. Processes with no need for frequent servicing can be in a queue with a larger quantum, requiring fewer context switches to complete the processing, and thus making more efficient use of the computer.
When is a cache useful?
Caches are useful when two or more components need to exchange data, and the components perform transfers at differing speeds.
What problems does a cache solve?
When two programs of different speed are sharing data, if the cache has the data the faster one needs, it doesn't have to wait for the slower one.
How does the distinction between kernel and user mode function as rudimentary security?
In user mode, some hardware, CPU calls, timer data, and interrupt controls are not available, limiting how much the user should be able to break the system.
Some early systems had a memory partition that was not modifiable by the user job or the os. What is the problem with this arrangement?
Passwords and other privileged data would have to be stored or passed through unprotected memory, becoming accessible.
In a dynamically linked library ____.
more disk space is used than the option of using a statically-linked library
Explain how the system can recover from a deadlock.
You can either abort all deadlocked processes or abort one process at a time until the deadlocked cycle is eliminated.
First and second stage boot loaders
First boot loader - small program in ROM that begins the loading of the OS into RAM.Second boot loader - Loads the OS itself, such as LILO, GRUB ect for dual-booting systems.
What is the purpose of system programs?
System programs are bundles of useful system calls so that users don't have to re-invent the wheel with common utility programs.
Give an example of RPC use.
A system wants to allow other systems to be able to list its current users. It would have a daemon supporting such a remote procedure call attached to a port. Any remote system could obtain the user list by sending an RPC message to that port. It would get the data back in a reply message.
Why does the dispatcher need to be fast?
Because it's invoked during EVERY process switch. The time it takes for the dispatcher to stop one process and start another is called dispatch latency.
Which of the following does a process need?
CPU time, memory, files, and I/O devices
What are some things to consider when selecting which order to abort a process when recovering from a deadlock.
Priority of the process.How long the process as computed and how much time it has remaining.How many resources the process has used and how many it needs to complete. How many processes need to be terminated. Is the process interactive or batch.
An employee has deleted important files on the network drive and needs them restored. You cannot find them in the Recycle Bin. Why?A Data on the removable drive is corruptB The removable drive is compressedC The removable drive is
D Files on the network drive are not stored in the recycle binWhen you are logged in to a network and delete a file resource from a shared drive on the network, it is not redirected to your recycle bin. Recycle bin will only contain the files that were existing locally and got deleted locally
Describe the many to one model of threads.
There's one kernel thread with many user level threads mapped to it. Management is done by the thread library in user space, which is efficient, but if one thread blocks, the whole process blocks. Since only one thread can access the kernel at once, it can't make use of multiprocessing.
How do average turnaround time and max waiting time conflict?
Things that give us very short turnaround time, like shortest job first scheduling, can leave jobs to wait a long time or potentially never even get done. If short jobs are preferred, some system has to be in place to make sure nothing is starved.
Timers can be used to compute the current time. How?
A sleeping program can update its status and sort out the current time based on a timer interrupt. If you had it sleep for ten seconds, when it awakens it is ten seconds later than it was when it went to sleep.
What are the three main thread libraries in use today?
POSIX Pthreads (user or kernel level) , WIN32 (kernel level), and Java (since running on a JVM usually, uses a thread library available on the host)
Deadlocks may only occur if all of these 4 conditions hold simultaneously.
1. Mutual Exclusion - only one process at a time can use a resource.2. Hold and Wait - a process holding at least one resource is waiting to acquire resources held by other processes.3. No preemption - a resource can be released only voluntarily by the processes holding it, after that process has completed its task.4. Circular wait - there is a set of waiting processes such that one of the processes is waiting for a resource that is held by another process which is also waiting for another process, etc etc.
In a peer to peer network, printing demands have slowed network performance. Which of the following offers a quick remedy to the problem?A Install more memory on the network printers.B Disable network printing on one of the computers th
C Run print jobs after hours when there is less network traffic.
Review Dekker's algorithm on page 269 and prove that it is a valid solution to the critical section problem.
Will do this in live review. Please pre-review.
What system calls have to be executed by a command interpreter or shell in order to start a new process?
In 'nix environments, we use fork and exec. Fork clones the currently executing process while exec overlays a new process based on a different executable over the calling process.
What are the main differences between operating systems for mainframes and PCs?
A PC must be more responsive to a user. Batch system OS may be more simple.
What are the four major categories of benefit derived from multithreading?
Responsiveness: even if one thread is blocked, the program may be able to respond to the user, still. Resource Sharing: Processes only communicate through shared memory or message passing and the like. Threads share the same memory and resources of the process they belong to. They share the same brain. Economy: Alloocating memory for process creation is costly, threads are more economical to create and context switch. Scalability: The more processors, the better it'll be.
You work for an ISP and are working with a customer who can only connect at 28.8k despite having a v.90 56K modem. What should you suggest to him first?A Check the internet for the latest v.90 updates for the modemB Replace the modem
A Check the internet for the latest v.90 updates for the modem
Describe the one to one model of threads.
Each user thread is mapped to a kernel thread. This causes a kernel thread to have to be generated for new user threads, so a limit has to be placed on the number of threads. Good for multiprocessing, good for letting a thread run while another thread is blocking. Linux and Windows both use this.
What does the exit section of the code do?
It follows the critical section. The book doesn't actually bother to say what it DOES, but it probably notifies something that this process is done with its critical section.
What are the three major activities of an operating system with regard to memory management?
Keep track of what memory is in use and by whom, decide which processes are to be loaded into memory when it becomes available, allocate and deallocate as necessary
what is the algorithm of predicting CPU burst?
τn+1 = α * tn + (1 - α) * τn
/ 115
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