Kernel Optimizations

The IRIX kernel has been carefully optimized for performance in a multiprocessor environment. Some of the optimizations are as follows:

Instruction paths to system calls and traps are optimized, including some hand coding, to maximize cache utilization.
In the real-time dispatch class (described further in "Using Priorities and Scheduling Queues"), the run queue is kept in priority-sorted order for fast dispatching.
Floating point registers are saved only if the next process needs them, and restored only if saved.
Paging I/O is prioritized with the process priority.
The kernel tries to redispatch a process on the same CPU where it most recently ran, in hopes of finding some of its data remaining in cache (see "Understanding Affinity Scheduling").