Intel Core Dual, Multicore Programming: Multi-core systems will definitely improve multi-threaded applications written for HT Technology enabled systems. Counting the number of physical processors correctly in a system is very important, even before the introduction of HT Technology since it is the building block of performance for multi-threaded applications in multi-processor machines. Read this article to learn more.

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By Khang Nguyen

A Hyper-Threading Technology (HT Technology) enabled system appears to have more processors than it actually has. With this technology, one physical processor with a single-core is seen as two logical processors. The term logical is used here purposely as these two logical processors are not the same as a dual physical processor. Windows* will report to have two CPUs instead of one. This can be a big problem for licensing software especially when implementing per-processor models, since a two-logical processor system doesn’t perform equally to the real dual-physical processor system. Now, with the introduction of multi-core, the licensing problem is getting worse.

A core is different from a logical processor. The core has its own set of execution units. Also, a core can have more than one logical processor associated with it. In a multi-core HT Technology enabled system, one physical processor can have a minimum of two cores (dual-core) and four logical processors.