Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
How could we implement locks? No matter how we choose to implement them, we must have some hardware support. One possibility for implementing locks on a uniprocessor machine is is to disable interrupts when testing/setting locks. With interrupts disabled on a single processor machine, the processor cannot switch processes, and so we can guarantee that only the active process will have access to the shared data. Another option would be to make use of atomic operations, such as test and set. This type of operation (which usually corresponds to a single atomic assembly instruction) behaves as if it used the following C function, atomically:
int test_and_set(int x) // let x be strictly either 0 or 1.{if (x) { return 1; } else { x=1; return 0; }}
All this needs to be implemented atomically, in hardware. Using this type of atomic operation, one could implement thread lock(l) simply as while test_and_set(l) {
; // do nothing} // spinlock version of thread_lock()and thread unlock(l) simply asl = 0; // we need this to be an atomic clear (or assign) instruction
The assembly instruction test and set can bemade to be atomic acrossmultiple processors. An equivalent option would be an atomic compare and swap assembly instruction. These low-level hardware solutions are then built up into high-level functions, either built into the languages, or in libraries. In general, do not implement your own locking functions, but rather use functions from a tested library. Getting things right can be tricky, and your own solution is also likely to be non-portable.
Q. Consider a calculating environment where a process is given the privilege of accessing object only n times. Suggest a scheme for implementing this policy. Answer: Add an i
Ask question #Minimum 500 words accepted#
Problem: a) Define a ‘file' and list the objectives of the file management system. b) List the ways in which programs access files and determine for what file types you woul
A practical task specified in the Study Guide, Computer architecture, was to record your computer's specifications. Submit the data you recorded, which will contain the following d
Q. It is occasionally said that tape is a sequential-access medium whereas magnetic disk is a random-access medium. In fact the correctness of a storage device for random access d
A hard-disk drive reads “120 GB HDD 7200 rpm 3 GB/sec transfer rate”. If the drive has a sector size of 512 bytes, what is the average rotational latency and transfer time to read
Define the properties operating systems: Batch :- Jobs with similar needs are batched together and run through the computer as a group by an operator or automatic job sequenc
Q. Why is rotational latency typically not considered in disk scheduling? How would you alter SSTF, SCAN and C-SCAN to comprise latency optimization? Answer: Most disks don't
Determine what the “blocking factor” of a file is Blocking factor is the number of logical records in one physical record
Explain the Fork-join This is primitives in a higher level programming language for implementing interacting processes. The syntax is like this: fork ; join ; where
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!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd