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A "ready" or "waiting" process has been loaded into main memory and is awaiting execution on a CPU (to be context switched onto the CPU by the dispatcher, or short-term scheduler). There may be many "ready" processes at any one point of the system's execution—for example, in a one-processor system, only one process can be executing at any one ...
Processes are also removed from the run queue when they ask to sleep, are waiting on a resource to become available, or have been terminated. In the Linux operating system (prior to kernel 2.6.23), each CPU in the system is given a run queue, which maintains both an active and expired array of processes.
A CPU-bound process, in contrast, generates I/O requests infrequently, using more of its time doing computations. It is important that a long-term scheduler selects a good process mix of I/O-bound and CPU-bound processes. If all processes are I/O-bound, the ready queue will almost always be empty, and the short-term scheduler will have little ...
Some second-level CPU caches run slower than the processor core. When the processor needs to access external memory, it starts placing the address of the requested information on the address bus. It then must wait for the answer, that may come back tens if not hundreds of cycles later. Each of the cycles spent waiting is called a wait state.
Process State – new, ready, running, waiting, dead; Process Number (PID) – unique identification number for each process (also known as Process ID); Program Counter (PC) – a pointer to the address of the next instruction to be executed for this process; CPU Registers – register set where process needs to be stored for execution for ...
In operating systems, processes are loaded into memory, and wait for their turn to be executed by the central processing unit (CPU). CPU scheduling manages process states and decides when a process will be executed next by using the input queue.
This state describes any process which is waiting for an I/O event to take place. In this case, an I/O event can mean the use of some device or a signal from another process. The three states in this model are: RUNNING: The process that is currently being executed. READY: A process that is queuing and prepared to execute when given the opportunity.
The context switch loads the process into the processor and changes the state to "running" while the previously "running" process is stored in a "waiting" state. If a process in the "running" state needs to wait for a resource (wait for user input or file to open, for example), it is assigned the "blocked" state. The process state is changed ...