This is a term paper done for the course of Opearing Systems.
Existing operating systems provide an interface for applications and services to run on and have easy and secured access to hardware resources. OS runs as a layer between hardware and software, so every access to those resources have several restrictions and rules; they can be called a policy. Two main types of today’s operating systems are monolithic a microkernel, as it seen from the names – the difference is in the structure of the kernel. Both of these approaches use certain policies for application level, usually seeing and making no difference between various programs asking for resources. Therefore, one or few policy schemes are used regardless program specifications, making the whole system less efficient. In many cases applications require far greater control over memory, I/O and processing resources than an OS can provide.
The paper (pdf) can be downloaded here.