Question

c programing language

When a new program is executed, a new process is created with the next available process ID. However, there are a few special processes that always have the same process ID, which are usually given the ID value less than 5 these are called system processes. Can you identify which of the two system processes have the process ID of 0 and 1 respectively?

Answer 1

Unix-like:

There square measure 2 tasks with particularly distinguished method IDs: swapper or sched has method ID zero and is accountable for paging and is really a part of the kernel instead of a normal user-mode process. method ID one is typically the init process primarily liable for beginning and motility down the system. Originally, method ID one wasn't specifically reserved for init by any technical measures: it merely had this ID as a natural consequence of being the primary method invoked by the kernel. more modern operating system systems generally have further kernel elements visible as 'processes', within which case PID one is actively reserved for the init method to keep up consistency with older systems.

Windows:

Under Microsoft Windows operating systems, one will get this process' ID using GetCurrentProcessId() API, and ID of alternative processes using GetProcessId() API. Internally, the method ID is termed a client ID and is allotted from identical namespace as thread IDs, thus these 2  overlaps. The System Idle method is given method ID zero, and System Process is given method ID four. In some versions of Windows, method and thread identifiers square measure all multiples of four, however, it's not a part of the specification.

System Idle Process:

System Idle Process contains one or a lot of kernel threads which run once no alternative runnable thread are often regular on a central processor. during a digital computer system, there's one idle thread related to every central processor core. For a system with hyperthreading enabled, there's associate degree idle thread for every logical processor.

The primary purpose of the idle method and its threads is to eliminate what would rather be a special case within the computer hardware. while not the idle threads, there may well be cases once no threads were runnable. Since the idle threads square measure invariably during a prepared state, this could ne'er happen. therefore whenever the computer hardware is termed because of this thread deed its central processor, another thread will invariably be found to run thereon central processor, albeit it's solely the CPU's idle thread. The CPU time attributed to the idle process is so indicative of the number of central processor time that is not needed or needed by the other threads within the system.

The computer hardware treats the idle threads as special cases in terms of thread programming priority. The idle threads square measure regular as if they ever had a priority less than are often set for any standard thread.