Round robin vs cyclic executive

[Manuv16589]

What is the difference between round robin and cyclic executive? As far as i know both uses time slicing to provide services periodically

 

[sky_123]

not really.. there is no time slicing (at least not on the context switching level) going on in the executive as such. basically, think of it this way: there are pre-emptive and co-operative OSs, and they both consist of processes or tasks that
need execution, and the former will automatically stop a process from running after a period of time and then allow the next process to run. The latter will allow the process to run until it signals that it is ready to hand over control to another process.
Now the _scheduling_ algorithm can be round robin, and it can apply to pre-emptive or co-operative OSs.
The cyclic executive is not really an OS, it is just a (poor) design pattern almost. It is just a loop. (Not that is is alway a bad solution. In fact for simple functions,
I'd rather use that instead of an OS. In conjunction with the usual interrupt service routines, you can get quite far for simple use-cases).

An OS does more that just process scheduling and task management (i.e. task creation and context switching and so on).
An OS also needs to have process synchronization and message passing, to allow the processes to run in a controlled fashion and be able to pass data.
This is probably all nicely documented in some book, but I don't know which is a good one. I remember the uC/OS book was quite easy to read and had
nice diagrams which explained all that, plus other process scheduling algorithms too.
However it is geared towards that OS however, so you probably want to find some other CompSci books too.

 

[Manuv16589]

Thanks for that elaborate and clear answer