Methods of providing synchronization
Synchronization can be provided by locks, semaphores, monitors, messages
A lock is a memory object with two operations:
acquire(): obtain the right to enter the critical section
release(): give up the right to
Synchronization is a mechanism that enables a shared variable or function to be accessed (executed) by
one process or thread at a time. All the processes that can access the common operations have a sequence
of instructions that in their c
Round Robin (RR)
Each process gets a small unit of equal CPU time (time quantum), usually 10-100
milliseconds. After this time has elapsed, the process is preempted and added to the end of
the ready queue.
If there are n processes in the ready queue and t
Types of Operating Systems
This section describes various types of Operating Systems.
Operating systems have been there from the very first computer generation. Operating systems keep
evolving over the period of time. Following are few of the important ty
The ways files can be implemented in a computer memory
i) Contiguous allocation:
Each file is stored as a contiguous run of disk blocks
Data items of a file are allocated consecutive disk blocks
It is simple to implement and has good performance
What is an Operating System?
A program that acts as an intermediary between a user of a computer and the computer hardware
Operating system goals:
Execute user programs and make solving user problems easier
Make the computer system convenient to use
Determines how the user threads are mapped to kernel threads. There are three models
Many user-level threads mapped to single kernel thread
Solaris Green Threads
A multicore system design is where multiple computing cores have been placed on a single
chip, and each core appears as a separate processor to the operating system.
Multithreaded programming provides a mechanism for more efficient u
A deadlock is an operating system condition in which a set of blocked processes each
holding a resource and waiting to acquire a resource held by another process in the set to
complete their execution.
A System has 2 disk drives
Benefits of multithreaded process
1. Responsiveness: Multithreading an interactive application may allow a program to
continue running even if part of it is blocked or is performing a lengthy operation, thereby
increasing responsiveness to the user. For i