Answer: Spinlocks are not appropriate for single-processor systems
because the condition that would break a process out of the spinlock can be obtained only by executing a different process
.
Are interrupts appropriate to be used for implementing synchronization primitives?
On a multiprocessor system, multiple threads can actually be running at the same time. … Explain why
interrupts are not appropriate
for implementing synchronization primitives in multiprocessor systems. Depends on how interrupts are implemented, but regardless of how, it is a poor poor choice of techniques.
Why is disabling the interrupts not considered a feasible solution in a multiprocessor environment?
But unfortunately, this solution is not as feasible in a multiprocessor environment. Since the message is passed to all the processors, disabling interrupts on
a multiprocessor can be time consuming
. System efficiency decreases when this massage passing delays entry into each critical section.
Why does interrupt disabling not work in a multiprocessor architecture?
It’s theoretically possible, but it’s not just “slow”, it’s impractical. Disabling interrupts on one core doesn’t make something atomic if other threads are running on other cores. Disabling interrupts works on uniprocessor machines
because it makes a context-switch impossible
.
What are the drawbacks of disabling interrupt give an appropriate example?
- One must be careful not to disable interrupts for too long; devices that raise interrupts need to be serviced!
- Disabling interrupts prevents all other activities, even though many may never execute the same critical region.
How could an operating system that can disable interrupts implement semaphores?
6. Give a sketch of how a uniprocessor operating system that can disable interrupts could implement semaphores. To do a semaphore operation, the operating system first
disables interrupts
. Then it reads the value of the semaphore.
What is synchronization primitives?
Synchronization primitives are
simple software mechanisms provided by a platform
(e.g. operating system) to its users for the purposes of supporting thread or process synchronization. They’re usually built using lower level mechanisms (e.g. atomic operations, memory barriers, spinlocks, context switches etc).
What are three requirements of any solution to the critical sections problem?
Three must rules which must enforce by critical section are : 1) Mutual Exclusion 2) Process solution 3)Bound waiting.
Why do we need process synchronization?
The need for synchronization originates
when processes need to execute concurrently
. The main purpose of synchronization is the sharing of resources without interference using mutual exclusion. The other purpose is the coordination of the process interactions in an operating system.
What are the three classical problems of synchronization?
- Bounded-buffer (or Producer-Consumer) Problem: Bounded Buffer problem is also called producer consumer problem. …
- Dining-Philosphers Problem: …
- Readers and Writers Problem: …
- Sleeping Barber Problem:
Why enabling disabling interrupts doesn’t suffice on a multiprocessor?
Code running on other processors can break that because they can access the resource at the same time
. Therefore, on a multiprocessor machine, disabling interrupts is not sufficient to achieve multiple exclusion. There also needs to be a way to prevent the other processors from accessing the resource.
Can user level code disable interrupts?
Kernel can’t allow user code
to get control with interrupts disabled (might never give CPU back!). … Real-time systems need to guarantee how long it takes to respond to interrupts, but critical sections can be arbitrarily long. Thus, one should leave interrupts off for shortest time possible.
Does disabling interrupts work in case of multiple CPUs?
If the process supports device interrupts on multiple CPUs, the interrupt handling on the CPUs is not concurrent: When interrupts are disabled on one CPU,
they are disabled on all CPUs
(unless, of course, if interrupts are needed for inter-CPU communication).
What are the possible problems with disabling interrupts?
By disabling interrupts
the CPU will be unable to switch processes
. This guarantees that the process can use the shared variable without another process accessing it. But, disabling interrupts, is a major undertaking.
Why is disabling interrupts bad?
1 Answer. Disabling interrupts on all CPUs, either intentionally or unintentionally,
will make the system completely unresponsive
.
Which of the following is true for disabling interrupts?
the answer is
d as test
and set lock can be implemented in multiprocessor system through the use of semaphore. in uniprocessor system it can be implemented by just disabling the interrupts . but in multiprocessor system disabling interrupt for all the process at the same time is not possible . so answer is d .
