If adaptive partitions aren't "boxes," what are they?

An adaptive partition is a named set of rules. The rules are selected to control the global resource behavior of the system.

When a process or thread is associated with a particular partition, then its actions are governed by the rules of that partition at that time.

For example, adaptive partitioning is similar to people who belong to clubs. Each person can join several different clubs. They can even move from club to club at times. But while they are at a particular club, they agree to abide by the rules of that particular club.

Partitions provide:

• memory protection—each partition is discrete and controlled by the Memory Management Unit (MMU)
• overload protection—each partition is guaranteed a slice of execution time, as specified by the system designer

By using multiple partitions, you can avoid having a single point of failure. For example, a runaway process can't occupy the entire system's resources; processes in other partitions still receive their allocated share of system resources.

Currently, QNX Neutrino's process model provides significantly more protection than some other operating systems do, including:

• full memory protection between processes
• message-passing to provide uniform and controlled IPC
• priority inheritance with a clean client-server model
• hard realtime deterministic scheduling
• a detailed permission model for devices, files, and memory
• memory, file-descriptor, CPU, and priority limits, using the POSIX setrlimit() function to constrain runaway processes