Tag: operating systems

Processes

PROCESSES concept a process is a program in execution, a processing unit managed by the OS (operating system). BCP (process control block) has the information of processes: allocated memory segments, open files, communication points. HIERARCHY when a process to solita to the OS created a process B, B is A child. In unix is respected, not in winnt. ENVIRONMENT of processes is a set of variables that are passed to the process at the time of its creation (table name-value pairs that is included in the process stack).

GROUPS of processes formed groups with various properties, created from a shell, dependent on a Terminal, etc. There are operations that can be done on all processes of a particular group (kill them all). Tasking MULTITASKING: or monoproceso, only allows a process in every moment (MS-DOS) multitasking: or multithreaded, coexist several processes at the same time, the OS, divides the processor processes time so all progress in its implementation. Single user: it supports a single user, they can be monoproceso or multithreaded. Multi-user: supports multiple users working simultaneously in different terminals, it is obligatorily multitasking. NULL process at intervals in which the defendant has nothing to do, the OS include a null process, it is an infinite loop that does nothing useful (the aim is to entertain the processor). Planner and ACTICADOR Scheduler (scheluder) enters running each time the OS activates and selects the process that will be executed next. The Activator (dispatcher) puts the selected process running by him Planner.

DEGREE of MULTIPROGRAMMING is the number of active processes that maintains the system. It affects significantly the performance of the computer. How many more active processes has, more likely to find a process in state ready to run, so you run less the null process. Higher multiprogramming, greater need for Menorca. Without virtual memory: the active processes reside entirely in main memory, the limited degree of multiprogramming this by the size of available memory and processes.

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