Operating system Advantages of using mult icore system (how) :

Before I start talking about how multicore system work I need to explain how it looks like and why did we go for using it.

We used to know that each computer processor (chip) has one CPU, the goal was to increase CPU clock cycles in order to speed up the execution,

but they couldn’t speed it up without having power dissipation and heat problems. The new direction is in increasing the number of processing cores on the same CPU die (multicores).

For example: a dual core has two CPU's so it's appear to OS as TWO CPU'S, and because the two processors are actually plugged into the same socket , the connection between them is faster. also the quad core is like 4 CPU's . All CPU's resides in one chip (die).

To exploit the potential of multicore chips, software needs to be written in parallelism programming.

In order to use multiple cores at the same time, multiple threads are required (the inverse is not true).

A thread is a basic unit of execution, it's scheduled by OS and executed by CPU.

In order to make each single core able to run multiple threads OS sets up a timer which interrupts the system at a fixed interval ( time slice ) .As the context switch is needed for switching between processes it also switches between threads .

To make it simpler and easier to understand see the example in the next page .

see the multicore system example ( email example )

As u noticed in the mail example, technically a program is a process divided into one or more threads, each of them are independent in their execution. OS perceives each core as a separate processor and the scheduler maps thread \processes to different core. So this whole system helps to increase performance and throughputs.

this is the conclusion ..