MP Overview

A multiprocessor is a system with two or more processing units that act in a controlled and parallel manner to carry out system activity. The figure shows the basic hardware diagram of multiprocessor system with two processors.

Figure 1-1 A sample MP system showing three processors

HP-UX multiprocessing has the following characteristics:

Two or more processors
The HP-UX MP implementation supports up to sixteen processors.
Symmetry
HP-UX is implemented as a symmetrical multiprocessor operating system. This means that each processor has equal capability to enable any kernel task to execute on any processor in the system. In fact, a thread will often execute on more than one processor during its lifetime. Threads are scheduled in a parallel fashion but this aspect is transparent to users.
Tight coupling
All processors have uniform access to all of main memory and any I/O device in a shared fashion. This characteristic classifies HP-UX MP as tightly coupled. (By contrast, an implementation where each processor has its own private memory and I/O is known as loosely coupled.)
Single Integrated Operating System
A single kernel controls all hardware and software in the HP-UX MP implementation. Locking and synchronization strategies provide the kernel the means of controlling MP events.

Each processor has its own data structures, including run queues, counters, time-of-day inforamtion, notion of current process and priority.
Global data structures are protected by semaphores and spinlocks.
Each processor has its own cache, TLB, registers, interrupts.




	NOTE: The hardware maintains cache coherency between all processors.

MP Overview

Technical documentation

» Table of Contents