Modern CPUs like these are shared memory multiprocessors. Programs on these CPUs are often designed to run on multiple cores at the same time to improve perform

Modern CPUs like these are shared memory multiprocessors. Programs on these CPUs are often designed to run on multiple cores at the same time to improve performance, necessitating communication between cores, to coordinate and share work between each other. Since each core typically has a private cache, most communication in a system like this will typically involve cache coherence protocols to ensure cores have a consistent view of memory contents. Adding more cores increases the overall complexity of the system. The latency of these protocols grows with more cores as interconnections become more "distant", across processor interconnects. Minimizing latency and effectively scaling to more cores is a difficult problem to solve while staying within silicon and thermal budgets.