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.
Dynamic scheduling : The number of thread in a program may be changed during the course of operation. Dynamic priority scheduling is a kind of scheduling algorithm in which the pr
A friend has promised to log in at a particular time. However, he needs to be contacted as soon as he logs in. The shell script checks after every minute whether he has logged in o
Define the “Throughput” of a system Throughput is Number of programs processed by it per unit time
Problem: a) The CPU can access 2 storage devices directly. What are these 2 storage devices? b) Define 2 key issues involved in memory management. c) How do processes sha
Write about critical regions and monitors. Critical region definition Monitor definition Implementation of the conditional-region construct Syntax of monitor Monito
What are the four necessary conditions of deadlock prevention? Ans: Four essential conditions for deadlock prevention: a. The meaning of removing the mutual exclusio
What are the differences between process and thread? The fundamental difference between a process and a thread is that a process has an entire copy of the program to itself and
Since each thread has its own processing space therefore communication between threads will need to be done through a common global variable. Since multiple threads can access the
Compare user threads and kernel threads. User threads:- User threads are supported above the kernel and are executed by a thread library at the user level. Thread creation
Q. What protection problems may occur if a shared stack is used for parameter passing? Answer: The contents of the stack could be conciliation by other process(es) sharing th
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