What is Multicore Processing?

Multiprocessing systems, whether discrete or multicore, can greatly improve your applications' performance. As described in the Multicore Processing chapter of the System Architecture guide, there's a multiprocessor version of Neutrino that runs on:

• Pentium-based multiprocessor systems that conform to the Intel MultiProcessor Specification (MP Spec)
• MIPS-based systems
• PowerPC-based systems

If you have one of these systems, then you're probably itching to try it out, but are wondering what you have to do to get Neutrino running on it. Well, the answer is not much. The only part of Neutrino that's different for a multiprocessor system is the microkernel — another example of the advantages of a microkernel architecture!

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To determine how many processors there are on your system, look at the num_cpu entry of the system page. For more information, see “Structure of the system page” in the Customizing Image Startup Programs chapter of Building Embedded Systems.

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Neutrino supports these operating modes for multiprocessing:

Asymmetric multiprocessing (AMP)

A separate OS, or a separate instantiation of the same OS, runs on each CPU.

Symmetric multiprocessing (SMP)

A single instantiation of an OS manages all CPUs simultaneously, and applications can float to any of them.

Bound multiprocessing (BMP)

A single instantiation of an OS manages all CPUs simultaneously, but you can lock individual applications or threads to a specific CPU.

SMP lets you get the most performance out of your system, but you might need to use BMP for the few applications that may not work under SMP, or if you want to explicitly control the process-level distribution of CPU usage.