Embedded Systems Design, 2nd Edition

Real-time operating systems 231

Fairness systems

There are times when the system requires different charac-

teristics from those originally provided or alternatively wants a

system response that is not priority based. This can be achieved by

using a fairness system where the bus access is distributed across

the requesting processors. There are various schemes that are

available such as round-robin where access is simply passed from

one processor to another. Other methods can use time sharing

where the bus is given to a processor on the understanding that it

must be relinquished within a maximum time frame.

These type of systems can affect the interrupt ...