Context switching is, as far as I know, essentially the same process in all multi-tasking operating systems.
Simplistically, in order for a multi-tasking operating system to switch tasks on and off a CPU, the operating system must be able to store and restore the state of the CPU for each process that shares that CPU. The act of storing and restoring the CPU state is referred to as context switching.
In a nutshell (an oversimplified nutshell), the states/values of the Instruction Pointer, the registers, accumulator etc. must all be saved for a given process for the OS (Operating System) to move to the next process in the queue. Once they are saved, the states/values of the next process in the queue can be loaded into those same registers etc. and that process can continue execution for 'N' number of instructions. Then this whole procedure is repeated for the next process in the queue. And so on, and so forth, ad infinitum...
Necessarily, MUCH is omitted in the above over simplification but it is hoped, none the less, that the above description provides some very general idea of what happens during a context switch.
The term context switching is a sort of catch all which may refer to and cover a number of more specific processes such as thread context switches, register context switches, task context switches etc.
This answer is necessarily over simplified as a full description of context switching is far beyond the scope deemed acceptable in this forum.
In any environment, in order to execute a privileged instruction you have have to switch from user mode to kernel mode, hence a context switch.
This includes the presence of a switch or option - in this case the 'a' option. Every command in Unix is free to interpret what they means differently as there is no universal meaning for this switch.
•No special support needed from the kernel (use any Unix) •Thread creation and context switch are fast (no syscall) •Defines its own thread model and scheduling policies
Some context might help. The closest thing I can think of is /dev/tty, which is a unix-style device name (in unix, printers, terminals, and the like are treated as files).
A user may switch their identities when logged in using the 'su' command. On some systems the 'su' command may be restricted.
There are many variations of the useradd command; most standard installations may not have this switch. Please identify which Unix system you are talking about.
When a context switch occurs, the kernel saves the context of the old process into its Program Control Block and loads the saved context of the new process scheduled to run.
Context switch must be atomic to ensure that the state of the system remains consistent during the switch. This is important because a context switch involves saving the state of the current process and loading the state of the next process. If the switch is not atomic, it could lead to data corruption or inconsistencies in the system, resulting in unpredictable behavior.
If the new context is already loaded into one of the register sets, a context switch involves simply changing the pointer to the register set in use. This is a faster operation as no actual data needs to be moved between memory and registers, resulting in a quicker context switch process.
Not switched. e.g. "The light was not switched off."
I'm not familiar with the term "tissino type switch." It may be a specific type of switch used in a particular industry or context. Can you provide more context or details so I can better assist you?
If the process that gets the control can be put into the register (its kept in cache though) means less time to fetch and have a context switch. Any way the context switching time isn't a big time delay.