The IP address range 127.0.0.0 – 127.255.255.255 is reserved for loopback. Loopback IP address is managed entirely by and within the operating system. These addresses enable the Server and Client processes on a single system to communicate with each other. When a process creates a packet with destination address as loopback address, the operating system loops it back to itself without having any interference of NIC.Data sent on loopback is forwarded by the operating system to a virtual network interface within operating system. This address is mostly used for testing purposes like client-server architecture on a single machine.For example, if ... Read More

Context Switching involves storing the context or state of a process or thread so that it can be reloaded when required and execution can beresumed from the same point as earlier. This is a feature of a multitasking operating system and allows a single CPU to be shared by multiple processes.A process switch or process scheduling is to changing one process from another by saving all of the state of the currently executing process, including its register state, associated kernel state, and all of its virtual memory configuration.A thread switch means switching from one thread to another thread within a ... Read More

In Linux, Top command is utilized to monitor Linux Process which is used frequently used by many systems. It is available under many Linux, Unix like operating system. All the running and active real-time processes in ordered list is displayed and updates it regularly by this Top command. display CPU usage, Swap memory, Cache Size, Buffer Size,Process PID, User, Commands and much more. It shows high memory and CPU utilization of running processes in your machine.The following command to monitor Linux Process is typed and it should access root permission.#topThe output should be like this –

All computers do not store the bytes that comprise a multi-byte value in the same order. Consider a 16-bit internet that is made up of 2 bytes. Two ways to store this value −Little Endian − In this scheme, low-order byte is stored on the starting address (A) and high-order byte is stored on the next address (A + 1).Big Endian − In this scheme, high-order byte is stored on the starting address (A) and low-order byte is stored on the next address (A + 1).To allow machines with different byte order conventions communicate with each other, the Internet protocols ... Read More

A program loaded into memory and executing is called a process. In simple, a process is a program in execution.When a program is created then it is just some pieces of Bytes which is stored in Hard Disk as a passive entity. Then the program starts loading in memory and become an active entity, when a program is double-clicked in windows or entering the name of the executable file on the command line. (i.e. a.out or prog.exe)Let’s look at each memory segment and how does a process look like within memory −Figure: Process in MemoryTEXTA process is more than the ... Read More

Deadlock can be occurred in a multithreaded Pthread program using mutex locks. Let’s see how it can be occurred. An unlocked mutex is initialized by the pthread_mutex_init() function.Using pthread_mutex_lock() and pthread_mutex_unlock() Mutex locks are acquired and released. If a thread try to acquire a locked mutex, the call to pthread_mutex_lock() blocks the thread until the owner of the mutex lock invokes pthread_mutex_unlock().Let’s take an example, two Mutex locks are created in the following Code −/* Create and initialize the mutex locks */ pthread mutex t mutex1; pthread mutex t mutex2; pthread mutex init(&mutex1, NULL); pthread mutex init(&mutex2, NULL);Next, two threads ... Read More

Transactional memory originated in database theory, provides an alternative strategy for process synchronization.A memory transaction is atomic is a sequence of memory read–write operations. The memory transaction is committed, if all operations in a transaction are completed. Otherwise, the operations must be aborted and rolled back. The ease of transactional memory can be obtained through features added to a programming language. Consider an example. Suppose we have a function update() that modifies shared data. Traditionally, this function would be written using mutex locks (or semaphores) such as the following −void update (){    acquire(); /* modify shared data */   ... Read More

Solaris implements variety of locks to support multitasking, multithreading and multiprocessing. It uses adaptive mutexes, conditional variables, semaphores, read-write locks, turnstiles to control access to critical sections.An adaptive mutex uses for protecting every critical data item which are only accessed by short code segments.On A multiprocessor system it starts as a standard semaphore spin-lock. If the lock is held by a thread which is running on another CPU then the thread spins. If the lock is held by a thread which is currently in run state, the thread blocks, going to sleep until it is awakened by the signal of ... Read More

Windows operating system is a multithreaded kernel that provide support for real time application and multiprocessors. On uniprocessor system, Windows provides interrupt masks to protect access to global resources. It protects access to global resource using spinlock. The kernel uses spinlocks only to protect short code segment like Solaris. The kernel ensures that while holding a spinlock, a thread will never be preempted.Windows provide dispatcher object for thread synchronization according to several different mechanisms including mutexes, semaphores, events and timers. The system protects shared data by requiring a thread to gain ownership of a mutex for accessing the data and ... Read More

To implement monitor using semaphores, for each monitor, a semaphore mutex (which is initialized to 1) is provided. Wait(mutex) must be executed by a process before entering the monitor and must execute signal(mutex) after leaving the monitor. Since a signaling process must wait until the resumed process either leaves or waits, an additional semaphore, next, is introduced, initialized to 0. next can be used by The signaling processes to suspend themselves. An integer variable next_count is also provided to count the number of processes suspended on next. Thus, each external function F is replaced by-wait(mutex); … body of F ... ... Read More