Main disadvantage of delayed writes correct answers Will result in a data loss if the system crashes at the wrong time
Main advantage of dual-mode CPUs correct answers Prevent user processes from directly accessing disk drives and other peripherals
Main advantage of timer interrupts correct a...
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Main disadvantage of delayed writes correct answers Will result in a data loss if the system
crashes at the wrong time
Main advantage of dual-mode CPUs correct answers Prevent user processes from directly
accessing disk drives and other peripherals
Main advantage of timer interrupts correct answers Prevent user processes from monopolizing a
CPU core
Main advantage of DMA controllers correct answers Speed up data transfers between the disk
drive and the main memory
Main advantage of lightweight processes correct answers Are much cheaper to create than
conventional processes
Main disadvantage of microkernals correct answers Introduce additional context switch delays in
the processing of requests
Main advantage of modular kernels correct answers Let users add new features to the kernal
Main advantage of time sharing correct answers Allows multiple interactive users to share the
same computer
Main advantage of multi-threaded servers correct answers Can process multiple client requests in
parallel
How can we prevent processes from accessing the address spaces of other processes and prevent
user processes from tampering with the kernel correct answers By adding memory protection
In a dual-mode CPU, how can the CPU switch from user mode to privileged mode correct
answers When it processes an interrupt (as the interrupt will leave the program counter in a safe
location INSIDE the kernel
What is the main difference between real-time applications with hard and soft deadlines? correct
answers Missing a hard deadline can have catastrophic consequences while missing a soft
deadline is a mere inconvenience
What would have happened if UNIX had remained written in assembly language correct answers
It would not have been ported to other architectures and would NOT have had the same impact
Why is fork() one of the costliest system calls? correct answers It requires making a copy of the
address space of the forking process
In which state is a process performing a disk I/O? correct answers In a WAITING STATE
, In which state is a process waiting for a core? correct answers In the READY STATE
How would you let a program read its standard input from the file input.txt correct answers fh =
open("data.txt", O_RDONLY);
close(0); // close stdio
dup(fh); //duplicate fh into stdio
close(fh);
Add the two system calls that will ensure that the program will print exactly once Hello World!
and Goodbye! in that order correct answers int main()
{
if (fork(0) == 0) {
printf("Hello World!\n");
_exit(0);
}
wait(0);
printf("Goodbye!\n");
}
What is the default action that a UNIX process takes when it receives a signal?
What can it do to prevent that from happening?
Is this always possible? correct answers -The process terminates
-The process can catch the signal
-NO, the SIGKIL signal cannot be caught, and signal number nine cannot be caught
Which events will bring a RUNNING process into a WAITING state? correct answers The
process issues a (blocking) system request
Which events will bring a WAITING process into the READY queue? correct answers The
completion of a pending system request
dup() correct answers Creates a duplicate of a given file descriptor
execv() correct answers Loads in memory the program to be executed by a given process
fork() correct answers Creates a new process
kill() correct answers Sends a signal to another process
lightweight processes correct answers Share the address space of their parent
microkernels correct answers Delegate most of their duties to user-level servers
pipe correct answers Used to send the standard output of a process to the standard input of
another one
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