Midterm: Processes, Threads, Scheduling, Intro to OS
What is a timer interrupt?
A time based interrupt to prevent infinite loops and process hogging
A clustered system: A) gathers together multiple CPUs to accomplish computational work B) is an operating system that provides file sharing across a network C) is used when rigid time requirements are present D) can only operate one application at a time.
A) gathers together multiple CPUs to accomplish computational work
Why would an application programmer prefer programming according to an API rather than invoking actual system calls?
APIs allow for compilation and execution on any system that supports that API
What is a system call?
An interface to the services made available by an operating system.
Which of the following would lead you to believe that a given system is an SMP-type system? A) Each processor is assigned a specific task. B) There is a boss-worker relationship between the processors. C) Each processor performs all tasks within the operating system. D) None of the above.
C) Each processor performs all tasks within the operating system
What statement concerning privileged instructions is considered false? A) They may cause harm to the system. B) They can only be executed in kernel mode. C) They cannot be attempted from user mode D) They are used to manage interrupts.
C) They cannot be attempted from user mode. (They can be *attempted* but the OS will determine the instruction illegal)
What is another term for kernel mode? A) Supervisor mode B) System mode C) Privileged mode D) All of the above
D) All of the above
The most common secondary storage device is _______. A) Random access memory B) Solid state disks C) Tape drives D) Magnetic disk
D) Magnetic disk
A _____ can be used to prevent a user program from never returning control to the operating system. A) portal B) program counter C) firewall D) timer
D) Timer
T/F: A dual-core system requires each core has its own cache memory.
False
The operating system handles process management, which includes....
creating and deleting user and system processes, suspending and starting processes, synchronizing processes, handling process communication, and handling deadlocks
What linux system call starts a new process?
fork()
The four components of a computer system:
hardware, operating system, application programs, and users
Multiprocessors systems are growing in importance due to advantages like:
increased throughput, economy of scale, increased reliability, can be used to run parallel applications
Multiprogramming is beneficial for the user because it ______.
increases CPU utilization, and keeps users satisfied by always having a program in execution.
An _______ is how the controller informs the device driver that it has finished its operation.
interrupt
When two or more processes share data, OS's will provide systems calls that allow a process to ______ shared data. Then, no other process can access the data until the lock is released.
lock
For each thread of a process, there is ______ program counter.
one
A single-threaded process has a program counter specifying location of next instruction to execute, while a multi-threaded process has.....
one program counter per thread to specify next execution location.
A ___________ is caused when access to a virtual memory location is not found in physical memory.
page fault
A program in execution is a _____.
process
In order to terminate a process, the CPU needs to ____________ its reusable resources.
reclaim
When passing parameters to a Linux OS, if there are less than six parameters, _______ are used. If there are more than five, then the _________ is used.
registers, block method
The status of the current activity of a process is represented by the value of ____.
the program counter
A ____ is a software-generated interrupt caused by an error or user request.
trap/exception
What is the difference between a thread and a process?
A process is an instance of a program, while a thread is the smallest execution unit of a process. Process = heavyweight, thread = lightweight.
What is a process?
A program in execution
What is the difference between a program and a process?
A program is a passive entity, like a file on your local drive, where a process is an active entity that is being executed.
What is the difference between a process and a program?
A program is a passive entity, while a process is an active entity
What is an operating system?
A program that acts as an intermediary between the computer hardware and the user.
What is a system daemon?
A program that runs the entire time the kernel is running.
A process needs resources to accomplish its task, like:
CPU, memory, I/O, files, and initialization data
A _________ is a multiprocessor system which gathers multiple CPUs; comprised of two or more individual systems joined together.
Clustered system
What is the difference between kernel mode and user mode?
Kernel mode is execution that takes place on behalf of the OS, while user mode is what the person can execute. Ex: computer running user application = user mode. When that program requests service from OS (system call), system transitions to kernel mode.
What does the system-call interface to?
It serves as the link to system calls made available by the operating system.
_________ (batch system) is an OS structure that organizes jobs so that CPU always has a job to execute via job scheduling
Multiprogramming
________ and _________ are used to determine which type of interrupt has occurred.
Polling/vectored interrupt system
What are the six types of system calls?
Process control, file management, device management, information maintenance, communications, and protection.
______ are the smallest, fastest type of memory, while _____ are the slowest, largest type.
Registers, magnetic tapes
What is the OS's process for handling a page fault?
The hardware generates a trap, the handler in the OS determines how to get this memory, if page is still on the disk then the handler allocates physical memory, makes an I/O request to the driver, driver copies page from disk into new physical page, and then OS restarts process at trapped instruction.
What is a bootstrap program?
The initial program a computer needs to execute to start running
What is virtual memory?
The mapping of hardware memory addresses to applications, using swapping or paging.
What is the kernel?
The operating system
Asynchronous I/O means....
The process completes on its own, which then signals an interrupt to begin the next process.
Synchronous I/O structure means....
The process or thread waits for the operation to complete.
________ (multitasking) is an OS structure that switches jobs frequently, and allows multiple users to run at least one program execution in memory
Timesharing
T/F: Flash memory is slower than DRAM but needs no power to retain its contents.
True
T/F: Interrupts may be triggered by either hardware or software.
True
T/F: System call interface is the boundary between user programs and operating system services.
True
Von Neumann computer architecture consists of...
a control unit, an arithmetic and logic unit (ALU), memory unit, registers, and I/O devices.
Device controllers are connected through a common ______ providing access to shared memory
bus