Mastering Embedded Linux Programming - Second Edition

Choosing a policy

In practice, time-shared policies satisfy the majority of computing workloads. Threads that are I/O-bound spend a lot of time blocked and always have some spare entitlement in hand. When they are unblocked, they will be scheduled almost immediately. Meanwhile, CPU-bound threads will naturally take up any CPU cycles left over. Positive nice values can be applied to the less important threads and negative values to the more important ones.

Of course, this is only average behavior; there are no guarantees that this will always be the case. If more deterministic behavior is needed, then real-time policies will be required. The things that mark out a thread as being real-time are as follows:

• It has a deadline by which it must ...