Multiple Cores, Single License

As AMD and Intel prepare to ship new processors that combine multiple CPUs, or cores, into a single package, Microsoft has announced that it will continue to count processors rather than cores for per-processor licensing of its software products. The announcement that the transition to multicore processors will not increase licensing costs allows customers to begin planning the acquisition and deployment of dual-core systems now, but in the future, multicore performance improvements might force some changes.

Hyperthreads, Cores, and Processors

Processor manufacturers find themselves between a silicon-based rock and a hard place—customers continue to demand more powerful processors, but power consumption and heat dissipation problems limit the density and clock speed that manufacturers can squeeze from their processors.

One solution is to enable processors to do more work with each clock tick by enabling them to run multiple instructions at the same time. For example, Intel’s hyperthreaded processors run multiple streams of instructions at once. However, all streams of instructions running on a hyperthreaded processor still share some resources, such as the processor’s onboard cache. Conflicting access to these resources limits the throughput of the processor.