OS - Difference between Scheduling Algorithms (RR, SJF...) and PCS or SCS

Question

I'm learning about the Operating System concepts. There's one thing I don't understand well regarding scheduling process and thread.

Process Scheduling algorithms (SJF, RR...) is a general term, which means that these algos are also used for Thread Scheduling.

However, it exists also PCS (user-level) and SCS (kernel-level) mechanisms for Thread Scheduling.

So what is the differences between SFC,RR...and SCS (or PCS) ?

Thank you very much.

Answer 1

Simply you can say it that,

PCS scheduling is completed locally to the process. It is how a thread library schedules threads onto available LWPs. SCS scheduling is the circumstances where the operating system schedules kernel threads. On systems utilizing either many-to-one or many-to-many, the two scheduling models are fundamentally different. On systems utilizing one-to-one PCS and SCS are the same.