Professional Multicore Programming: Design and Implementation for C++ Developers

Chapter 8. PADL and PBS: Approaches to Application Design

	Even if parallel processing is done on a project, there really isn't much change in actual processing efficiency — there's just a diversity of output.
	--Shirow Masamune, Ghost in the Shell: Man-Machine Interface

Chapter 4 illustrated the role the operating system plays for applications that have a requirement for parallelism or multicore support. In it, we explained how the processes and kernel threads are the only execution units that the operating system schedules for processor execution. In Chapters 5 and 6, we explained how processes and threads are created and are used to gain access to Chip Multiprocessors (CMPs), but processes and threads are relatively low-level constructs. The question remains, "How do you approach application design when there is a concurrency requirement or when the design model has components that can operate in parallel?" In Chapter 7, we explored mechanisms that support Interprocess Communication (IPC): mutexes, semaphores, and synchronization. These are also low-level constructs that require intimate knowledge of operating-system-level Application Program Interfaces (APIs) and System Program Interfaces (SPIs) in order to program correctly.

So far we have discussed only scenarios that involved dual or quad core processors. But the trend in CMP production will soon replace dual and quad core processors. The UltraSparc T1, which we introduced in Chapter 2, has eight cores on a single chip with ...