Multicore Processors

MultiCore Processors

Definition: A multicore processor is a single integrated circuit (a.k.a., chip multiprocessor or CMP) that contains multiple core processing units, more commonly known as cores. There are many different multicore processor architectures, which vary in terms of

• Number of cores. Different multicore processors often have different numbers of cores. For example, a quad-core processor has four cores. The number of cores is usually a power of two.
• Number of core types.
  • Homogeneous (symmetric) cores. All of the cores in a homogeneous multicore processor are of the same type; typically the core processing units are general-purpose central processing units that run a single multicore operating system.
  • Heterogeneous (asymmetric) cores. Heterogeneous multicore processors have a mix of core types that often run different operating systems and include graphics processing units.
• Number and level of caches. Multicore processors vary in terms of their instruction and data caches, which are relatively small and fast pools of local memory.
• How cores are interconnected. Multicore processors also vary in terms of their bus architectures.
• Isolation. The amount, typically minimal, of in-chip support for the spatial and temporal isolation of cores:
  • Physical isolation ensures that different cores cannot access the same physical hardware (e.g., memory locations such as caches and RAM).
  • Temporal isolation ensures that the execution of software on one core does not impact the temporal behavior of software running on another core.