Dynamic Processors Demand Dynamic Operating Systems
The rise of multicore processors has lead to techniques that dynamically vary the set and characteristics of cores or threads available to the operating system. For example, Core Fusion merges multiple cores for faster processing. While the mechanics of the change, such as merging two cores into a more powerful core, can be handled by a virtualization layer, operating systems still have an interest in the exact set of cores available. For example, the read-copy-update mechanism in Linux must contact all cores to complete an update. Thus, the OS must be informed when the set of CPUs changes.