Explain a computing environment, Operating System

Assignment Help:

Q. Polling for an I/O completion is able to waste a large number of CPU cycles if the processor iterates a busy-waiting loop several times before the I/O completes. However if the I/O device is ready for service polling can be much more proficient than is catching and dispatching an interrupt. Explain a hybrid strategy that combines sleeping, polling, and interrupts for I/O device service. For every of these three strategies (pure polling, pure interrupts, hybrid) explain a computing environment in which that strategy is more efficient than is either of the others.

Answer: A hybrid approach could switch among polling and interrupts depending on the length of the I/O operation wait. For instance we could poll and loop N times and if the device is still busy at N+1 we could set an interrupt and sleep. This approach would evade long busy-waiting cycles. This process would be best for very long or very short busy times. It would be incompetent it the I/O completes at N+T (where T is a small number of cycles) because of the overhead of polling plus setting up and catching interrupts.

Pure polling is best with extremely short wait times. Interrupts are best with known long wait times.


Related Discussions:- Explain a computing environment

Define buffering, Define buffering. A buffer is a memory area that keep...

Define buffering. A buffer is a memory area that keeps data whereas they are transferred among two devices or among a device and an application. Buffering is done for three rea

Execution without entering a deadlock state, Q. Presume that a system is in...

Q. Presume that a system is in an unsafe state. Illustrate that it is possible for the processes to complete their execution without entering a deadlock state. Answer: An unsaf

Enforce memory protection at compile time?, Why is it not possible to enfor...

Why is it not possible to enforce memory protection at compile time?   Every process should be protected against unwanted interference by other process, whether intentional or

Linux, Discuss the risks of having a single root user

Discuss the risks of having a single root user

How does ntfs handle data structures, Q. How does NTFS handle data structur...

Q. How does NTFS handle data structures? How does NTFS recover from a system crash? What is guaranteed after a recovery takes place? Answer: In NTFS all file-system data stru

What is low-level formatting, What is low-level formatting? Before a di...

What is low-level formatting? Before a disk can kept data, it must be required into sectors that the disk controller can read and write. This procedure is called low-level form

Write a short note on pcb, Write a short note on PCB? Every process is ...

Write a short note on PCB? Every process is represented in the operating system by a process control block also called a task control block. It contains more information regard

Deadlock prevention, While it is hard to resolve a deadlock which has been ...

While it is hard to resolve a deadlock which has been detected, fortunately it is fairly easy to prevent deadlocks from ever happening. The key is that the conditions above for dea

Define lazy swapper, Define lazy swapper. Rather than swapping the enti...

Define lazy swapper. Rather than swapping the entire process into main memory, a lazy swapper is used. A lazy swapper never swaps a page into memory unless that page will be ne

First-in-first-out (fifo), FIFO is named as 'named pipes'. FIFO (first-in-...

FIFO is named as 'named pipes'. FIFO (first-in-first-out) is a special file which is laid to be data transient. Once data is load from named pipe, it cannot be load again. Also, da

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd